AHE-450-DE5 Service Manual

Introduction:

This service and parts manual is designed to aid trained and qualified service technicians with the process of troubleshooting and servicing the Aqua-Hot 450D Hydronic heating system.

About the Aqua-Hot:

The Aqua-Hot 450D heating system features a 12V DC powered diesel-burner and a 120VAC 1650 Watt electric heating element. These two heating sources are used in conjunction with an FDA-approved “GRAS” (Generally Recognized as Safe) propylene glycol based boiler antifreeze and water heating solution in order to provide a continuous supply of domestic hot water, interior/fresh water tank heating, independent interior zone heating, and engine preheating. Be sure to reference Figures 5 through 8 for a complete component overview.

Understanding the Aqua-Hot 450’s Major Systems:

The basis for the Aqua-Hot heating system’s functionality is the antifreeze and water heating solution, which is comprised of water that is distilled, deionized, or soft, as well as FDAapproved “GRAS” propylene glycol based boiler antifreeze. Through this solution’s ability to maintain and transfer heat, the Aqua-Hot’s three major systems: the domestic water system, engine preheat system, and interior heating system, are able to function effectively. This antifreeze and water heating solution is contained within the Aqua-Hot’s boiler tank and is heated by the diesel-burner when its operating criteria are met and/ or by the electric heating element when its operating criteria are met. In order for the diesel-burner to be considered as a heating source by the Aqua-Hot, it must have an adequate fuel supply, receive power from the Reporter, and be selected as a heating source from the interior switch panel. In order for the electric heating element to be considered as a heating source by the Aqua-Hot, it must receive power from either a generator or from shore power and be selected as a heating source from the interior switch panel. Once the antifreeze and water heating solution achieves operating temperature (as determined by the Aqua-Hot’s control thermostat/ETS Module), the domestic water system, the engine preheat system, and the interior heating system are permitted to operate as needed.

Domestic Hot Water Priority System:

The Aqua-Hot 450D is a Hot Water Priority System. Meaning that the Aqua-Hot 450D cannot heat the interior of the motor home, and produce continuous hot water simultaneously. When Domestic Hot Water is being used, the interior heating system will shut down, until no more Domestic Hot Water is called for. The domestic hot water priority system is responsible for providing hot water whenever a hot water faucet is opened, such as with a shower or sink. When hot water is requested, domestic water from the motor home’s fresh water tank is transported through a copper coil in the Aqua-Hot’s boiler tank where heat is transferred from the heated antifreeze and water heating solution to the domestic water flowing through the copper coil. The heated domestic water then flows through the tempering valve to be mixed with cool water from the fresh water tank to achieve an appropriate temperature before it flows to the faucet requesting hot water.

Engine Preheat System:

The engine preheat system is responsible for heating the motor home’s engine block in order to make it easier to start-up when cool weather conditions exist. When the engine preheat system is activated via the interior switch panel, the motor home’s engine coolant is circulated through a dedicated copper coil in the Aqua-Hot’s boiler tank, where heat from the antifreeze and water heating solution is transferred to the motor home’s engine coolant. The heated engine coolant is then transported back to the engine where it transfers the heat to the engine to gradually warm it. Additionally, the Aqua-Hot 450D includes a motor-aide feature, which uses the circulation of the motor home’s engine to transport the engine’s coolant from the Aqua-Hot’s boiler tank to the motor home’s warm engine and back to the boiler tank. Through this process, the boiler tank is kept heated, which reduces the time required to bring the tank to operating temperature for interior heat and continuous domestic hot water. This motor-aide feature is part of the engine preheating feature and plumbing system, and requires no action on the user’s behalf to function.

Interior Heating System:

The interior heating system is responsible for providing heat to the motor home’s interior in order to maintain the temperature at a comfortable level. For interior heating, it is the room thermostats that trigger the Aqua-Hot’s interior heating system. When a thermostat recognizes that heat is required in a particular area, it sends a signal to the Aqua-Hot’s Reporter calling for heat. The Aqua-Hot responds by activating the circulation pump for that zone, which sends the heated antifreeze and water heating solution through the Heating Loop corresponding to the zone requesting heat. The fans on the heat exchangers in the zone calling for heat are also activated; therefore, as the heated solution flows over the heat exchanger’s fins, the heat is transferred to those fins and dispersed into the interior of the motor home by the fans. Until the thermostat signals that heat is no longer required, the Aqua-Hot will continue to send the heated antifreeze and water solution through the loop, which returns the cooled solution to the Aqua-Hot’s boiler tank to be reheated before being sent back through the loop again. This process continues until the preset temperature of the interior is reached, and the interior room thermostat signals the Reporter that heat is no longer required.

AC Circuit:

Although the diesel-burner is the primary heating source for the Aqua-Hot and is necessary for providing continuous domestic hot water, an alternate heat source exists for moderate temperatures, which functions with an AC circuit. Whenever the motor home is connected to an AC power source, plugged into shore power or using a generator, the Aqua-Hot’s electric heating element has the ability to function in order to provide heat for the boiler tank. When the antifreeze and water heating solution falls below operating temperature (as determined by the control thermostat/ETS Module), a signal is sent to the Reporter requesting heat. Because the electric element switch is activated on the interior switch panel, the DC power from the Reporter is permitted to flow to the AC relay, which activates the relay in order to allow AC power to flow to the electric heating element. When the electric heating element receives power, it becomes active and supplies heat to the boiler tank until operating temperature is reached.

System Features

Component Callouts

Operational Flow Chart

Antifreeze and Water Heating Solution

Introduction:

As the antifreeze type and mixture ratio is essential to the Aqua-Hot’s performance and ability to comply with regulations, the following information is being supplied to understand various types of antifreeze, the quality of water necessary, and the mixture ratio. Aqua-Hot Heating Systems recommends Century Transfer Fluid.

Antifreeze Types:

The following information addresses the necessary usage of a propylene glycol based “boiler “ type antifreeze in the Aqua-Hot. Propylene glycol is a safer alternative to the more toxic ethylene glycol antifreeze; however, as mandated by IAPMO (International Association of Plumbing and Mechanical Officials),only those propylene glycol based“boiler”type antifreezes deemed “Generally Recognized as Safe” (GRAS) by the FDA should be utilized. Because of the significant impact various types of antifreeze can have on a Hydronic heating system, including the level of safety provided, it has been recognized that there is a need to provide an explanation regarding two additional prominent types of antifreeze/coolant available. The following information should be utilized as an educational means of ensuring that the proper type of propylene glycol based anti-freeze is selected.

RV and Marine Antifreeze:

These types of propylene glycol based antifreeze products are formulated specifically for “winterizing” applications only. Although RV & Marine antifreeze is often “Generally Recognized as Safe” by the FDA, it should never be used in the Aqua-Hot’s Hydronic Heating System. This type of anti-freeze is not formulated to transfer heat, which is essential to the heating system’s functionality and does not contain rust inhibitors. Please note, however, that RV & Marine anti-freeze can be utilized to winterize the Aqua-Hot’s domestic water heating system.

Automotive Antifreeze/Coolant:

These types of propylene glycol based antifreeze products are formulated specifically to protect automotive engines against corrosion, freezing temperatures, and overheating. They also have excellent heat transfer and thermal conductivity characteristics. Although these types of antifreeze products are considered less toxic and safer than ethylene glycol for people, pets, and the environment, they are not “Generally Recognized as Safe” (GRAS) rated by the FDA. Therefore, they must be marked with a “harmful if swallowed” warning. This additional warning is required because these types of antifreeze products contain high levels of chemical inhibitors. Due to their potentially hazardous properties, they should never be used in the Aqua-Hot’s Hydronic Heating System.

Antifreeze Mixture Water Quality:

In order to ensure maximum performance and longevity of an Aqua-Hot heating system’s boiler tank and associated components, it has been determined that there is a need to use distilled, deionized, or soft water in combination with concentrated propylene glycol for the Aqua-Hot’s antifreeze and water heating solution,. Please note that this is only necessary when mixing concentrated propylene glycol antifreeze with water; suppliers of premixed antifreeze are responsible for the use of high quality (distilled, deionized, or soft) water when preparing their antifreeze for sale. Hard water possesses a high-level of calcium and magnesium ions, which deplete the propylene glycol antifreeze’s corrosion inhibitors. This, in turn, causes the antifreeze and water heating solution to begin turning acidic, which can corrode the Aqua-Hot’s boiler tank and associated components prematurely. Therefore, concentrated propylene glycol should be diluted with distilled, deionized, or soft water that is 80 PPM or less in total hardness. The local water agency should have up-to-date water quality reports that should indicate if the local tap water is within this guideline.

Antifreeze Terms and Mixture Ratio:

The following information addresses the process of selecting an antifreeze and water mixture ratio that provides adequate freeze, boiling, and rust/anti-corrosive protection. A 50/50 mixture of propylene glycol/water ratio is recommended, which will result in a freeze point of approximately -28°F and a boil point of approximately 222°F. The following information should be utilized for the purpose of clarifying some terms commonly associated with antifreeze.

Freeze Point and Burst Point:

Antifreeze lowers the freezing point of any liquid, to which it has been added, by preventing the formation of ice crystals; however, as the ambient temperature continues to decline, the water in the solution will attempt to attain a solid state. The point in which the water begins to solidify is termed the “Freeze Point.” Although the water in the solution has begun to freeze, producing a “slushy” consistency, the anti-freeze in the solution will continue to combat the normal expansion of the solution as it freezes. The point in which the solution can begin to expand, due to colder temperatures, is called the “burst point.” Once the solution reaches the burst point, the potential is present for ruptured pipes to exist. The burst point of the antifreeze and water heating solution is dependent upon the brand of propylene glycol employed.

Boiling Point:

The Aqua-Hot utilizes the antifreeze and water heating solution as a transportation means for the heat produced from the internal processes. The antifreeze absorbs the heat created until its boiling point is reached; it is at this point that the liquid turns to a gas and is expelled to prevent the heating system from overheating. Each time the boiling point is reached, a loss of efficiency occurs because the heat produced is expelled rather than used for the function of the heating system. Therefore, a higher boiling point is desired in order to combat the loss of efficiency, which allows the antifreeze to transport the heat created from the internal process throughout the motor home where it can be used productively rather than dissipating due to its change from a liquid to a gas.

Rust and Corrosion Inhibitors:

Another major function of antifreeze is to provide protection to the internal metal components of the Aqua-Hot Hydronic heating system from corrosion and rust. Antifreeze is able to perform this function by the addition of rust-and anti-corrosive inhibitors, which are designed specifically to activate in a water solution.

Summary:

Antifreeze has three basic functions: freeze protection, boil-over protection, and anti-corrosion and rust protection. Antifreeze is also primarily responsible for heat transfer characteristics. Therefore, as water is an excellent heat conductor, it is added to the mixture. A 50/50 solution of propylene glycol antifreeze and water is recommended to provide the best performance combination of the aforementioned functions. If excess propylene glycol exists within an antifreeze and water heating solution, the water’s heat absorption properties are compromised, which could ultimately inhibit the Aqua-Hot from providing adequate domestic hot water and interior heating. Additionally, if the antifreeze and water heating solution contains over 70 percent antifreeze, the freezing point is actually raised, resulting in less freeze protection.

Interior Switch Panel

Introduction:

The interior switch panel is used to control the two potential heating sources for the Aqua-Hot’s boiler tank, as well as to control the engine preheat feature. When a switch is activated, the indicator light on the switch will illuminate.

Coach Control Panel Screen:

Newer Aqua-Hot units that come equipped with the Reporter may have a coach touch-screen display instead of the interior switch panel. Please confirm with your coach dealer or vehicle manufacturer the location and functionality of your interior control screen.

Diesel-Burner Switch:

When the diesel-burner switch is in the ON position and the control thermostat or ETS Module tells the Reporter that heat is needed for the boiler tank, the diesel-burner will respond by firing up and providing heat. A cold boiler tank can expect to be brought to operating temperature by the diesel-burner in approximately 10 to 20 minutes. In order to obtain continuous hot water, the diesel-burner switch must be activated. Additionally, the diesel-burner switch can be used to reset a low-voltage condition. This is accomplished by turning off the diesel-burner switch for 30 seconds, then turning it back on, or by resetting the Reporter.

Electric Element Switch:

When the motor home is plugged into an AC power source (e.g., shore power, generator, etc) and the electric element switch is on, the electric heating element will be used to provide heat to the boiler tank if the need arises. A cold boiler tank can expect to be brought to operating temperature by the electric heating element in approximately 1 to 2 hours. The electric element, alone, will not be able to provide continuous hot water.

Engine Preheat Switch:

The engine preheat switch activates the engine preheat pump, which draws the motor home’s engine coolant through the boiler tank to heat it before returning it to the engine block to transfer the heat there. Either the diesel-burner switch or the electric element switch must also be activated in order for the engine preheat feature to function. The engine preheat switch does not need to be activated for the motor-aide feature to work and should be shut off when traveling.

Exhaust System Requirements

Introduction:

The following section will detail the specific Exhaust System Requirements of the Aqua-Hot 450D. Follow these requirements without deviation to ensure optimal unit operation. Because the Aqua-Hot’s exhaust is hot and must be kept away from any heat-sensitive material, the exhaust system should be checked to ensure that it continues to meet the following requirements: 

Installation Guidelines:

• The exhaust must NOT be directed downwards, as a fire could result under certain conditions
• The exhaust must NOT terminate beneath the vehicle, beneath an open-able window
• The exhaust must NOT vent in the awning area of the motor home or near the slide-out areas
• The exhaust must be able to freely exit away from the vehicle without any obstructions
• 2-in standard automotive-type exhaust pipe should be used
• Total exhaust length must NOT exceed 20 feet, and shall contain no more than two 90° bends
• The 3-in and 4-in black pipe nipples and the exhaust elbow - originally supplied with the Aqua-Hot must be present

Interlock Switch

Introduction:

The interlock switch is a safety device designed to ensure that the Aqua-Hot’s access cover is securely installed before allowing the diesel-burner to operate. If the Aqua-Hot fails to operate, and shows no illuminated lights or displays, it is possible that the interlock switch is faulty. Follow the directions below to troubleshoot, and if necessary, replace the interlock switch.

Troubleshooting:

1. Turn the diesel-burner switch on from the interior switch panel and ensure that the boiler tank has sufficiently cooled in order to require heat from the diesel burner.
2.  Verify that the “Diesel-Burner Status” is ON on the Reporter, and that the tank temperature is below 190°F.

3. Disconnect the two yellow wires from the interlock switch noting that wire #24 is connected to the terminal labeled “NO” and wire #25 is connected to the terminal labeled “COM.”
4. Using an ohmmeter, check the interlock switch for continuity while the button is pushed in.

If continuity is not present with the button pushed in, follow the instructions in this section to replace the interlock switch.

Replacement Procedure:

1. Disconnect the Aqua-Hot from all power sources.
2. Disconnect the interlock switch’s wires by pulling the quick connectors from the switch’s spade terminals.
3. Release the interlock switch from the Aqua-Hot cabinet by pushing in on the locking tabs and pulling the interlock switch.
4. Remove the defective interlock switch from the Aqua-Hot.
5. Install the replacement interlock switch onto the Aqua-Hot ensuring that the locking tabs snap into place.
6. Connect the Aqua-Hot’s wires to the replacement interlock switch with yellow wire #24 connected to the terminal labeled “NO” and yellow wire #25 connected to the terminal labeled “COM.”

Fluid-Level Sensor

Introduction:

The fluid-level sensor monitors the level of antifreeze and water heating solution within the Aqua-Hot’s boiler tank to ensure that an adequate volume exists.

Troubleshoot the fluid-level sensor if the Reporter has issued a low fluid level fault and the Aqua-Hot is adequately filled.

The fluid-level sensor operates by relaying a continuity signal to the Reporter while it is wet. If this signal does not exist, then there may be an issue with the Reporter, OR the fluid level sensor may be physically damaged. Follow the directions below to troubleshoot the fluid level sensor.

Troubleshooting Procedure:

1. Verify that the wires terminating at the fluid level sensor are not damaged, corroded, or otherwise faulty.
2. Verify that the wires terminating at the Reporter are not damaged, corroded, or otherwise faulty.
3. Clamp the zone hoses shut to prevent the zones from draining into the Aqua-Hot.

4. Drain approximately 2 gallons of fluid into an external container to be reused.
5. Using a 3/16” wrench, or deep socket, loosen and remove the fluid level sensor from the tank face. 
6. If the sensor is corroded or the stainless steel rod is corroded, rusted, or otherwise damaged the fluid level sensor will need to be replaced.

Please note that if the sensor is covered in residue, it may be functioning improperly. If this occurs, clean the sensor off and retest the Aqua-Hot for functionality BEFORE replacing the fluid level sensor.

Replacement Procedure:

1. Clamp the zone hoses shut to prevent the zones from draining into the Aqua-Hot.

2. Drain approximately 2 gallons of fluid into an external container to be reused.
3. Remove the nut securing the wire in place on the fluid level sensor.
4. Using a 3/16” wrench, or deep socket, loosen and remove the fluid level sensor from the tank face.
5. Discard this sensor.
6. Place the new sensor in position on the tank face and finger tighten it into place.
7. Using a 3/16” wrench or deep socket, tighten the sensor until it is snug. DO NOT OVER TIGHTEN THIS SENSOR.
8. Reconnect the previously disconnected wire to the new fluid sensor.
9. Test the Aqua-Hot for normal operation.

Coolant Temperature Sensor (ETS)

Introduction:

The ETS module precisely measures the temperature of the coolant inside of the Aqua-Hot boiler tank. This allows for very granular control of the unit to deliver precise heating and hot water as needed.

The ETS module went live on the Aqua-Hot 450-DE5 series. Older units utilized the control thermostat.

The ETS module should be diagnosed if the Reporter is displaying an incorrect temperature when accompanied by issues such as lack of interior heat or hot water.

Troubleshooting Procedure:

1. Locate the thermostat within the Aqua-Hot and its associated wires.
2. Verify that these wires are not corroded, cut, or otherwise damaged.
3. Check the J8-6 and J8-3 pins on the Reporter to check for cut, corroded, or otherwise damaged wiring.
4. Using a meat thermometer, measure the temperature of the tank face of the Aqua-Hot.
5. Record this temperature on a notepad.
6. Locate the Reporter, and access the home page.
7. Find the element entitled “COOLANT TEMP”.

8. If the temperature displayed is not approximately the same as the temperature recorded earlier, the ETS module will need to be replaced.

Replacement Procedure:

1. Clamp shut the zone hoses to prevent the zone from draining.
2. Open the unit drain valve located on the bottom left of the heater, and allow approximately 2 gallons to drain from the unit.
3. Disconnect the wires of the existing ETS module.
4. Using a 10mm socket deep-well socket, remove the defunct ETS module and discard it.
5. Place the new ETS module onto the tank face, and finger tighten it.
6. Using a 10mm deep-well socket, tighten the ETS module until it is snug. DO NOT OVER-TIGHTEN THE ETS MODULE.
7. Reconnect the wires of the ETS module.
8. Test the Aqua-Hot for normal operation.

AC High-Limit Thermostat

Introduction:

The AC High-Limit thermostat serves as a safety measure in the event that the electric heating element continues to operate after the maximum operating temperature is reached. The high-limit thermostat allows the current for the heating element to pass through it until the boiler tank reaches a temperature of 215°F. Should this temperature be reached, the high-limit thermostat blocks the current to the element, which prevents it from continuing to provide heat to the boiler tank.

Begin troubleshooting the AC High-Limit Thermostat if the Reporter issues an overheat fault, or the electric heating element fails to operate correctly.

Troubleshooting Guidelines:

The following conditions must be met before the AC High Limit Thermostat can be diagnosed, and if necessary, repaired.

• The fluid expansion bottle is filled to at least the “COLD” mark.
• Verify that all in-line fuses are functional.
• Ensure that the unit is completely cool.
• Ensure that DC electrical power is supplied to the Aqua-Hot.
• Ensure that AC electrical power is supplied to the Aqua-Hot’s electric element.

If any of the above conditions are not met, correct them before continuing with troubleshooting. Results of the troubleshooting procedure cannot be verified if the conditions listed above are not fulfilled.

Troubleshooting Procedure:

1. Disconnect all power supplies.
2. Remove the AC access cover.
3. Verify that the boiler’s tank temperature is below 215°F,
4. Locate the AC high-limit thermostat and remove its wires.
5. Using an ohmmeter, check the thermostat for continuity.

• If there is no continuity, press the white reset button on the thermostat and recheck for continuity.
• If continuity is still not present after the reset button has been pressed, follow the instructions in this section to replace the AC high-limit thermostat.

Replacement Procedure:

1. Ensure that the Aqua-Hot has been completely shut down, and that all power supplies have been disconnected.
2. Remove the AC access cover.
3. If applicable, remove the heat shrink insulation covering the wires and terminals on the defective high-limit thermostat.
4. Disconnect the high-limit thermostat from the electric element and AC relay by removing the screws with a Philips screw driver.
5. Using a ⅝” wrench or socket, remove the defective high limit thermostat from the Aqua-Hot’s boiler tank.
6. Install the replacement high-limit thermostat into the port on the Aqua-Hot’s boiler tank and finger tighten only (15 in-lbs). 
7. Connect the wires on the replacement high-limit thermostat in the same configuration as they were removed.
8. Secure the AC access cover back into place.
9. Test for proper operation.

DC High-Limit Thermostats

Introduction:

The DC high-limit thermostats serve as a safety measure in the event that the diesel-burner continues to operate after the maximum operating temperature is reached. The high-limit thermostats allow the current for the diesel-burner to pass through them until the boiler tank reaches a temperature of 215°F. Should this temperature be reached, the high-limit thermostat blocks the current to the diesel-burner’s fuel solenoid valve, which prevents the diesel-burner from operating.

Begin troubleshooting the DC High-Limit Thermostats if the Reporter issues an overheat fault, or the diesel-burner or fuel solenoid fails to operate correctly.

Troubleshooting Guidelines:

The following conditions must be met before the High-Limit Thermostats can be diagnosed, and if necessary, repaired.

• The fluid expansion bottle is filled to at least the “COLD” mark.
• Verify that all in-line fuses are functional.
• Ensure that the unit is completely cool.
• Ensure that DC electrical power is supplied to the Aqua-Hot.

If any of the above conditions are not met, correct them before continuing with troubleshooting. Results of the troubleshooting procedure cannot be verified if the conditions listed above are not fulfilled.

Troubleshooting Procedure:

1. Place a jumper wire between the blue and purple wires on the diesel-burner’s wire harness to bypass the high-limit thermostats. Check the Aqua-Hot for normal operation.

2. Disconnect the DC high-limit thermostats’ wires, then with an ohmmeter, check each thermostat for continuity. If there is no continuity, complete the following:

• Press the reset button on the high-limit thermostat, then recheck for continuity.
• Disconnect the wires from each thermostat and recheck each thermostat for continuity, as well as each of the thermostats’ individual wires.
• If an individual wire does not have continuity, that wire must be replaced.
• If a thermostat with the wires removed that has been reset does not have continuity, follow the instructions in this section to replace the high-limit thermostat.

Replacement Procedure:

1. Ensure that the Aqua-Hot has been completely shut down, and that all power supplies have been disconnected.
2. Remove the two wires from the defective high-limit thermostat by pulling firmly on the wires.
3. Using a ⅝” wrench or socket, remove the defective high-limit thermostat from the Aqua-Hot’s boiler tank.
4. Install the replacement high-limit thermostat into the port on the Aqua-Hot’s boiler tank and finger tighten only (15 in-lbs). 
5. Connect the wires removed from the defective high-limit thermostat to the replacement high-limit thermostat.

Low-Temperature Cutoff Thermostat

Introduction:

The low-temperature cutoff thermostat (LTCO) operates the domestic hot water priority system by blocking the interior heating feature when domestic hot water is being used. This ensures that even heat is provided for domestic hot water, which avoids the possibility of cold water pockets during showers, etc.

Begin troubleshooting the Low-Temperature Cutoff Thermostat if the following conditions have occurred:

• There is a lack of interior heat
• There is a lack of hot water

Troubleshooting Procedure:

1. Locate the Reporter and navigate to “INPUTS FROM AQUA-HOT”

2. Turn on a hot water faucet within the coach. Monitor the Reporter screen.
3. Confirm the Low Temp Sensor element displays “HOT WATER”. If it displays “INTERIOR HEAT”, locate the LTCO in the Aqua-Hot cabinet.
4. Using a multimeter, test the LTCO for continuity.
5. If the LTCO does not have continuity while hot water is running, follow the procedure to replace the LTCO.

Replacing the Low-Temperature Cutoff Thermostat:

1. Disconnect the wires from the LTCO by separating the quick-disconnect terminals.
2. Remove and discard the defunct LTCO thermostat using a ⅝” wrench.
3. Position and secure the new LTCO thermostat into place. Hand tighten only to 15 in-lbs. Do NOT over-tighten.
4. Connect the replacement low-temperature cutoff thermostat’s wires in the same configuration as the removed thermostat’s wires.

Check Valves

Introduction:

Check valves are installed into the zone outlet ports for each heating loop to ensure that the antifreeze and water heating solution only flows in one direction. If the heating solution attempts to back flow into the boiler tank, the check valve closes to prevent that from happening.

Troubleshoot the check valves if there is a lack of interior heat in a particular zone.

Troubleshooting Procedure:

1. Verify that the heating zone is operating properly by checking the following:

• Check the Reporter “DIAG” screen on OPERATING MODE to ensure that the heating zone is on.

• Check the “OUTPUTS TO AQUA-HOT” to ensure the corresponding pump is on.

2. With the circulation pump operating, tap on the check valve and wait five minutes to evaluate if interior heat is now present.

• If interior heat is present after tapping the check valve, the check valve was stuck closed and no further action is needed.

3. Check the Aqua-Hot’s antifreeze and water heating solution’s ratio of water to propylene glycol. The mixture ratio should be approximately 50/50. If the solution is comprised fully of antifreeze (100%), the check valves will continue to stick.

Replacing the Check Valve:

1. Ensure that the Aqua-Hot has been completely shut down and that all power sources have been disconnected. Be sure the boiler tank has adequately cooled.
2. Drain the antifreeze and water heating solution from the boiler tank using the drain valve.
3. Using constant tension pliers, loosen and slide back the constant tension clamp securing the hose to the defective check valve.
4. Remove the hose from the defective check valve.
5. Unscrew the defective check valve from the Aqua-Hot’s boiler tank.
6. Remove the hose barb and the ½” coupler from the defective check valve.

7. Clean the hose barb and coupler, then wrap the hose barb and ½” coupler pipe threads with Teflon tape.
8. Install the hose barb and ½” coupler on the replacement check valve, ensure that they are installed properly with the hose barb on the arrow side of the check valve.
9. Install the replacement check valve onto the boiler tank. The arrow on the check valve must point away from the tank.
10. Slide the hose back onto the replacement pump and set the constant tension clamp back into place.
11. Refill the Aqua-Hot’s boiler tank with the antifreeze and water heating solution.

Tempering Valve

Introduction:

The tempering valve for the Aqua-Hot mixes the heated domestic water from the boiler tank with cold domestic water from the coach’s fresh water tank to reduce the risk of scalding.

Testing Procedure:

Follow the testing procedure to the right in order to diagnose the tempering valve. Troubleshoot the tempering valve if the following conditions have occurred:

• A lack of hot water.
• Hot water supply is uneven.
• Hot water is too hot.

1. Inspect the tempering valve to ensure that is not leaking.
2. Test the temperature of the hot water using a digital thermometer at one of the hot water faucets. Water temperature should range between 115°F - 123°F. If the proper range cannot be set follow the instructions in this section to replace the tempering valve.
3. Test the tempering valve’s functionality by turning the knob. If the tempering valve knob does not turn freely, follow the instructions in this section to replace the tempering valve.

Replacement Procedure

1. Turn the motor home’s water pump off.
2. Drain the water pressure by opening the faucets and allowing the water drain.
3. Disconnect the motor home’s water lines from the tempering valve assembly.
4. Disconnect the PEX pipe and fittings from the tempering valve assembly. 
5. Remove the pressure relief valve assembly from the tempering valve assembly as the tempering valve cannot be removed from the Aqua-Hot with the pressure relief valve still attached.

6. Using a back-up wrench, unscrew the tempering valve from the Aqua-Hot.
7. Remove the brass fittings from the defective tempering valve.

8. Clean the brass fittings if necessary, then wrap the threaded fittings with Teflon tape.
9. Install the brass fittings onto the replacement tempering valve.
10. Install the replacement tempering valve onto the Aqua-Hot using a back-up wrench to tighten.
11. Install the pressure relief valve onto the replacement tempering valve.
12. Reconnect the PEX tube and fittings to the tempering valve and the Aqua-Hot. Be sure to inspect the rubber seals and replace if necessary.
13. Reconnect the motor home’s water lines to the tempering valve assembly.
14. Turn the motor home’s water pump back on and check for leaks and for any presence of hot domestic water.
15. Verify that the replacement tempering valve has been set to the proper setting by taking a digital thermometer to a hot water faucet and set the water temperature between 115°F - 123°F.

Circulation Pumps

Introduction:

The circulation pumps first draw the heated antifreeze and water heating solution from the Aqua-Hot’s boiler tank, then propel it through the Hydronic heating system’s interior heat plumbing.

Troubleshoot the circulation pumps if the pump is not operating with the status ON on the Reporter, or the Reporter is showing an OVER-CURRENT fault for that pump.

Troubleshooting Procedure:

1. Verify the Low Temp Cutoff (LTCO) is showing on the Reporter, as it will be whenever the boiler tank is at operating temperature and domestic hot water is not being used.

2. Turn on the interior room thermostat corresponding to the circulation pump not operating (heating zones 1 & 5 operate with pump #1, and heating zones 2, 3, & 4 operate with circulation pump #2). Check the Zone status on the Reporter as shown below.

3. Test the pump directly to determine that the Reporter is sending a signal to the pump to operate. Follow the steps to test that the pump is receiving power from the Reporter

4. If the pump does not operate after testing, use a voltmeter to check for 12V DC power at the Reporter on J2 (pin # will depend on which pump is faulty - refer to the schematic on page 98).

• If the pump testing is ON and there is not 12V DC power at the J2 pin, the Reporter will need to be replaced.
• If the Reporter is sending 12V DC power to the pump, and the pump is not operating, follow the replacement procedure to replace the defective pump.

Replacement Procedure

1. Ensure that the Aqua-Hot has been completely shut down and that all power sources have been disconnected. Be sure the boiler tank has adequately cooled down.
2. Drain the antifreeze and water heating solution from the boiler tank using the drain valve.
3. Disconnect the defective pump’s wires by pulling out on the “Red Locking” tab on the harness plug, and separate the harness plug from the defective pump.
4. Using constant tension pliers, loosen and slide back the constant tension clamps securing the hoses to the pump.
5. Remove the hoses from the defective pump.
6. Release the pump from the mounting bracket by inserting an AWL between the locking teeth and gently prying the locking teeth apart. Remove the defective pump.
7. Slide the hoses onto the replacement pump and set the constant tension clamps back into place.
8. Install the replacement pump onto the mounting bracket, and squeeze the pump bracket together with a pair of channel lock pliers to secure the pump.

9. Reconnect the harness plug into the replacement pump. Be sure to push in on the red locking tab to secure the plug into place.
10. Refill the boiler tank with the antifreeze and water heating solution previously drained.

Stir Pump /Circulation Pump #3

Introduction:

The stir pump circulates the antifreeze and water heating solution within the Aqua-Hot’s boiler tank in order to ensure even heating of the solution. To accomplish this, the stir pump draws the solution from the bottom of the tank and immediately deposits it back into the top of the tank.

Troubleshoot the stir pump if there is a lack of hot water or the Reporter is showing an OVER-CURRENT fault for the pump.

Troubleshooting Procedure:

1. Verify the Low Temp Cutoff (LTCO) is showing on the Reporter, as it will be whenever the boiler tank is at operating temperature and domestic hot water is not being used.
2. Power cycle the Aqua-Hot to clear any current faults.
3. Navigate to the TESTING page on the Reporter and activate the stir pump. If the pump does not activate, test for voltage on the Reporter on pins J2-7 & J2-8.

• If no voltage is present, the Reporter will have to be replaced.
• If there is voltage, follow the steps to replace the stir pump.

Replacement Procedure

1. Ensure that the Aqua-Hot has been completely shut down and that all power sources have been disconnected. Be sure the boiler tank has adequately cooled down.
2. Drain the antifreeze and water heating solution from the boiler tank using the drain valve.
3. Disconnect the defective stir pump’s wires by pulling out on the “Red Locking” tab on the harness plug, and separate the harness plug from the defective pump.
4. Using constant tension pliers, loosen and slide back the constant tension clamps securing the hoses to the pump.
5. Remove the hoses from the defective stir pump.
6. Release the pump from the mounting bracket by inserting an AWL between the locking teeth and gently prying the locking teeth apart. Remove the defective pump.
7. Slide the hoses onto the replacement pump and set the constant tension clamps back into place.
8. Install the replacement pump onto the mounting bracket, and squeeze the pump bracket together with a pair of channel lock pliers to secure the pump.
9. Reconnect the harness plug into the replacement pump. Be sure to push in on the red locking tab to secure the plug into place.
10. Refill the boiler tank with the antifreeze and water heating solution previously drained.

Engine Preheat Pump

Introduction:

The Engine Preheat circulation pump draws the cold antifreeze and water heating solution from the motor home’s engine and then transports it through the Engine Preheat heat exchanger that is located inside the boiler tank.

Troubleshoot the Engine Preheat pump if the pump is not operating, the Engine Preheat switch is on, Pump 4 is showing ON on the Reporter, and the “Low Temp Cutoff” indicator is showing on the Reporter.

Troubleshooting Procedure:

1. Verify the Low Temp Cutoff (LTCO) is showing on the Reporter, as it will be whenever the boiler tank is at operating temperature and domestic hot water is not being used.
2. Verify that the Engine Preheat switch is in the ON position on the interior switch panel. Either the burner or electric switch need to be on as well.
3. On the Reporter, verify that PUMP 4 is on, along with the Low Temp Sensor, and the Electric or Burner.

• If not, make sure the boiler tank is up to temperature and the burner/electric is turned on. If they are, there may be an issue with the Reporter.

4. Navigate to the TESTING page on the Reporter and activate PUMP 4. If the pump is not operating after activating it on the Reporter, check for 12V DC power at the J2 Pins, J2- 10 & J2-11. If voltage is present, follow the replacement procedure to replace the Engine Preheat pump. If no voltage is present, the Reporter will need to be replaced.

Replacement Procedure

1. Ensure that the Aqua-Hot has been completely shut down and all power sources have been disconnected. Make sure the heater is adequately cooled.
2. Using hose pinch off pliers, clamp both hoses attached to the engine preheat pump closed.
3. Disconnect the defective pump’s wires by pulling on the “Red Locking” tab on the harness plug, separating the harness plug from the defective pump.
4. Using constant tension pliers, loosen and slide back the constant tension clamps securing the hoses to the engine preheat pump.
5. Remove the hoses from the defective pump.
6. Release the pump from the mounting bracket by inserting an Awl between the locking teeth and gently pry the locking teeth apart. Remove the defective pump from the Aqua-Hot.
7. Slide the hoses onto the replacement pump and set the constant tension clamps back into place.
8. Install the replacement pump onto the mounting bracket and squeeze the pump bracket together with a pair of channel lock pliers to secure the pump.
9. Reconnect the harness plug into the replacement pump. Be sure to push in on the red locking tab to secure the plug into place.
10. Remove the hose pinch off pliers previously installed on both hoses.
11. Test the Aqua-Hot for normal operation.

AC Electric Element

Introduction:

The electric heating element uses AC power as an alternate power source for heating the Aqua-Hot’s boiler tank.

Begin troubleshooting the electric element if there is a lack of hot domestic water and/or interior heat when the electric element is selected as the heating source.

Troubleshooting Guidelines:

The following conditions must be met before the electric heating element can be diagnosed, and if necessary, replaced.

• The fluid expansion bottle is filled to at least the “COLD” mark.
• Verify that all in-line fuses are functional.
• The AC high-limit thermostat is operating and not tripped.
• Ensure that the unit is completely cool.
• Ensure that DC electrical power is supplied to the Aqua-Hot.
• Ensure that AC electrical power is supplied to the Aqua-Hot’s electric element.

If any of the above conditions are not met, correct them before continuing with troubleshooting. Results of the troubleshooting procedure cannot be verified if the conditions listed above are not fulfilled.

Troubleshooting Procedure:

1. Verify that the motor home is either plugged into shore power or that the generator is running to provide AC power and the electric switch is ON on the interior switch panel.
2. Verify that the Electric shows ON on the Reporter.

• If the interior switch is on, the Reporter is not showing the electric as ON, and the tank is below 215°F, the Reporter will need to be replaced.

3. Verify that the boiler’s tank temperature is below 215°F.

• If the boiler tank temperature is below 158°F, test the control thermostat/ETS Module.
• If the boiler tank is above 158°F, the Aqua-Hot is at operating temperature and requires no heat.

4. Verify the Reporter is sending 12V DC to the AC relay by going to the TESTING page and see if the AC relay makes a “click” sound. The AC electric relay should let out an audible click from within the Aqua-Hot cabinet

• If no “click sound”, the AC relay and Reporter will need diagnosing.
• If there is “click” sound, continue troubleshooting the element.

5. Verify the electric element is receiving adequate AC power with an AC voltmeter. Remove the AC access cover and test for 110V AC power at the terminal block. If there is no voltage at the terminal block, there is an issue inside the motor home.
6. Verify the element’s amp draw is between 11.2 - 13 amps.
7. Check the element’s wires for continuity:

• Disconnect the motor from shore power, or shut off the generator.
• Disconnect the wires from the element and the AC terminal block.
• Check the black and white wires at the terminal block for continuity.

8. Check the element for functionality by testing resistance. Using an ohmmeter, the element should be between 8.5 - 9.5 ohms. If not, follow the replacement procedure to replace the element.

Replacement Procedure:

1. Ensure that the Aqua-Hot has been completely shut down and that all power sources have been disconnected. Make sure the boiler tank is adequately cooled.
2. Drain the antifreeze and water heating solution from the boiler tank using the drain valve.
3. Remove the AC access cover.
4. Remove the two wires secured to the defective electric element by releasing the screw terminals.
5. Using a 1-½” socket, remove the defective element from the Aqua-Hot’s boiler tank.
6. Install the replacement 1650W element into the boiler tank ensuring that the “up” lettering on the element is installed in the proper position.
7. Connect the wires removed from the defective element to the replacement element and tighten the screw terminals.
8. Reinstall the AC access cover.
9. Refill the boiler tank with the previously drained antifreeze and water heating solution.

AC Relay

Introduction:

The AC relay is an electric where DC circuit from the Reporter determines whether AC power is permitted to flow to the electric heating element. This allows the Reporter to switch the electric heating element on and off in conjunction with the interior switch panel and ETS Module/control thermostat even though the electric heating element is on a separate circuit.

Begin troubleshooting the AC relay if the electric heating element fails to operate.

Troubleshooting Guidelines:

The following conditions must be met before the electric heating element can be diagnosed, and if necessary, replaced.

• The fluid expansion bottle is filled to at least the “COLD” mark.
• Verify that all in-line fuses are functional.
• The AC high-limit thermostat is operating and not tripped.
• Ensure that the unit is completely cool.
• Ensure that DC electrical power is supplied to the Aqua-Hot.
• Ensure that AC electrical power is supplied to the Aqua-Hot’s electric element.

If any of the above conditions are not met, correct them before continuing with troubleshooting. Results of the troubleshooting procedure cannot be verified if the conditions listed above are not fulfilled.

Troubleshooting Procedure:

1. Disconnect the AC power source to the motor home (unplug from shore power or shut off the generator).
2. Verify that the Electric shows ON on the Reporter.

• If the interior switch is on, the Reporter is not showing the electric as ON, and the tank is below 215°F, the Reporter will need to be replaced.

3. Using a voltmeter, check for 12V DC on pins 12 & 13 on the J2 plug of the Reporter.

• If 12V DC are not present with the Electric status ON and the tank is below temperature, the Reporter will need to be replaced.
• If 12V DC are present, locate the AC wires connected to the AC relay and remove the AC wires from the relay
• Using an ohmmeter, check the AC relay pins for continuity. If no continuity exists, the AC relay will need to be replaced.

Replacement Procedure:

1. Ensure that the Aqua-Hot has been completely shut down and all power sources have been disconnected.
2. Make sure the motor home is not connected to shore power and the generator is not connected during this procedure.
3. Remove the AC access cover.
4. Release the wires from the defective AC relay by removing the corresponding screw terminals.
5. Remove the defective relay by drilling the rivets that hold the defective relay in place.

6. Rivet the replacement AC relay to the AC access cover.
7. Using the schematic on page 100, connect the wires previously removed to the replacement AC relay.
8. Reinstall the AC access cover and test for proper operation.

Aqua-Hot Reporter

Introduction:

The Aqua-Hot Reporter is a new generation of command and control module which manages all functions of the Aqua-Hot from start-up to shutdown. The previously used electronic control board has been retired on new units in favor of the Reporter.

Electrical Specifications:

The Reporter contains a single Amphenol ATP family connector that serves as the power connection to the coach side 12V DC power system. Mating connection components are not supplied by Aqua-Hot. Compatible part numbers and manufacturers are supplied below. The Reporter must be operated to the below listed specifications.

Minimum Voltage............................................................................................................................................................................................................................................................................................................................................................11.0V DC

Maximum Voltage........................................................................................................................................................................................................................................................................................................................................................15.0 V DC

Minimum Current...................................................................................................................................................................................................................................................................................................................................................................75mA

Maximum Current.......................................................................................................................................................................................................................................................................................................................................................................15A

Please note that the minimum current rating is the minimum requirement for what will operate the Reporter. Operating at this current rating will not provide sufficient power to any components dependent upon the Reporter.

Input Load currents

• Zone Thermostats (each)...............................................................................................................................................................................................................................................................................................................................appx. 1mA
• Diesel Burner Switch.........................................................................................................................................................................................................................................................................................................................................appx. 1mA
• Electric Element Switch...................................................................................................................................................................................................................................................................................................................................appx. 1mA
• Low-Level Cutoff Switch............................................................................................................................................................................................................................................................................................................................... appx. 1mA
• Control Thermostat (Reporter 1.0)..........................................................................................................................................................................................................................................................................................................appx. 1mA
• Tank Temperature Sensor (Reporter 2.0)...........................................................................................................................................................................................................................................................................................appx. 1mA
• Low-Temperature Cutoff Thermostat.....................................................................................................................................................................................................................................................................................................appx. 1mA

Output Load currents

• Zone Fans (Reporter 1.0/all)..........................................................................................................................................................................................................................................................................................................................3.0A max
• Zone Fan 1 (Reporter 2.0)...............................................................................................................................................................................................................................................................................................................................8.0A max
• Zone Fans 2-5 (Reporter 2.0)......................................................................................................................................................................................................................................................................................................................5.0A max
• Zone Fans (all)......................................................................................................................................................................................................................................................................................................................................................0.25A max
• Circulation Pumps (each)................................................................................................................................................................................................................................................................................................................................2.0A max
• AC Relay.......................................................................................................................................................................................................................................................................................................................................................................0.5A max
• Burner Power............................................................................................................................................................................................................................................................................................................................................................6.0A max
• Burner Master Control.......................................................................................................................................................................................................................................................................................................................................2.0A max
• Burner Thermostat Control..............................................................................................................................................................................................................................................................................................................................1.0A max

Connection Terminal Information

Replacement Procedure:

1. Ensure that the Aqua-Hot has been completely shut down and that all power sources have been disconnected. 
2. Remove the four screws that are securing the Reporter.
3. Disconnect the positive and ground wires from the back of the Reporter.
4. Disconnect the Aqua-Hot terminal plugs by pushing on the tabs and pull away from the Reporter.
5. Disconnect the coach-side connections by loosening the screws on each plug and pull away from the Reporter.
6. Install each terminal strip and plug back to the Reporter and tighten the screws for the coach-side connections.
7. Connect the ground wire, followed by the main 12V DC power wire to the replacement Reporter.
8. Reinstall the replacement Reporter and secure with the four screws previously removed.
9. Ensure that all electrical connections are made with the Aqua-Hot and the onboard RV-C system (if applicable) and that power is supplied to the new Reporter.
10. Tap the Reporter screen to wake the unit. Select “NEXT”.

11. Press and hold “S/N” for 6 seconds and release. You will be displayed with an option screen.

12. Tap “SERIAL NUMBER”. The data entry pad will be displayed and here you can enter the serial number shown on the Aqua-Hot Identification label. Tap “ENTER”. The Reporter will not accept invalid serial numbers.

Reporter Back Side

Manual Mode

The 2.0 Reporters with CFG 1.9 and greater come with a manual mode in case the general coach RV-C network fails. It will allow for limited operation while the larger network/module problem is addressed. To determine the version of Reporter, the Reporter 2.0 modules are shipped with version decals affixed to the back of the circuit board, OR shown on the home screen - “FW: 2.0”.

This mode can be accessed under the test page of the Aqua-Hot Reporter (see below).

Once the test page is open, select the MANUAL MODE and select “NEXT”. Manual mode will continue to run for up to 3 days without any user intervention. Pressing the reset button at any time while enabled will reset the timer, and run for an additional 3 days.

All heating zones are linked together and can be run at 25%, 50%, 75%, and 100% (as shown below). The burner and electric can be enabled or disabled. For all levels, there is a 10 minute duty cycle period that will allow Cozy fans to be on for the specified percentage of 10 minutes. Example, 25% would be on for 2.5 minutes, and then off for 7.5 minutes. It always starts with the on-cycle, then shuts off for the remainder of the 10 minute period.

If the system power is cycled, the manual mode will be disabled and must be manually reactivated. Leaving the manual mode page will also disable manual mode and restore normal operation. Leaving manual mode should be done once the system failure has been resolved and normal operation can resume.

Diesel Burner

Introduction:

The Aqua-Hot’s diesel burner is a device that ignites a mixture of diesel fuel and air within a controlled setting to serve as a heat source. The flame is established in a combustion chamber within the Aqua-Hot’s boiler tank, and the heat from the flame is transferred to the antifreeze and water heating solution where it can be used for each system of the Aqua-Hot - domestic hot water, interior heat, and engine preheat.

Diesel Burner Operation

Detaching the Burner

Instructions for Detaching the Diesel Burner

Step 1: Turn off the diesel switch

Light on the interior switch panel should turn OFF when switch is turned to OFF. Or the burner status should show OFF on the coach interior control panel.

Step 2: Remove the Access Cover

• Locate the bolt securing the access cover in place, unscrew the bolt.
• Remove the access cover.

Step 3: Disconnect the Diesel Burner’s Controller

Locate the controller and disconnect both plugs.

Step 4: Remove the fuel lines from the Aqua-Hot

• Locate where the fuel lines on the diesel burner connect to the Aqua-Hot bulkhead fittings.
• Using a 7/16” wrench, loosen the nuts securing each fuel line to the Aqua-Hot.

Step 5: Remove the Diesel Burner from the Aqua-Hot

The diesel burner is secured to the Aqua-Hot with two nuts that can be loosened, and swung out of the way by using a 10mm socket wrench with a 10” long extension.

Carefully pull the diesel burner away from the Aqua-Hot 4 to 5 inches before rotating the burner up, and then remove.

Reattaching the Diesel Burner to the Aqua-Hot

Step 1: Reattach the Diesel Burner to the Aqua-Hot

The diesel burner is secured to the Aqua-Hot with two eye-bolt nuts that can be swung into place, after the diesel burner has been properly aligned and set in place.

The eye-bolt nuts can then be tightened by using a 10mm socket with a 10 inch long extension. Use extreme caution when tightening down the eye-bolt nuts. Over-tightening the eye-bolt nuts can cause the aluminum blower casing to crack. (Torque Specifications are approximately 20-40 in-lbs.)

Step 2: Reattach the fuel lines to the Aqua-Hot

Align the fuel lines on the diesel burner with the fittings on the Aqua-Hot, and using a 7/16” wrench, tighten down both the supply and return fuel fittings.

Step 3: Reconnect the Controller and Mount

Locate the diesel burner’s Controller and connect both plugs that were previously disconnected.

Step 4: Reinstall the Access Cover

Reinstall the Aqua-Hot’s access cover and securely tighten the three bolts securing the access cover in place.

Burner Components

Troubleshooting

Wire Gauge Information:

Because all Aqua-Hot heating systems are designed to operate only when there is an adequate supply of DC (Direct Current) voltage, it is imperative that the proper wire gauge be determined and used for the DC power supply and ground wires. This section addresses how to determine the DC amperage draw of the heating system, including heat exchangers, and how to determine the proper wire gauge based upon those findings for a specific application.

On the Front Side of the Aqua-Hot:

1. Review the chart above for the amperage draw of the Aqua-Hot heater
2. Determine the number of heat exchangers installed with the heating system.
3. Consult the heat exchanger’s manufacturer for amp-draw information
4. Determine the total amperage draw for all heat exchangers installed.

• For example, if six Aqua-Hot Cozy heat exchangers have been installed, multiply the amperage draw of each heat exchanger (0.23 amps) by the number of heat exchangers (6). The total amperage draw in this scenario would be 1.38 amps.

5. Add the total heat exchanger amperage draw to the amperage of the installed Aqua-Hot.

• For example, an Aqua-Hot 450DE with six Cozy heat exchangers has a total amperage draw of 20.38 amps.

Determining the Proper Wire Gauge:

1. Measure the total length of wire required for the distance between the vehicle’s battery and the Reporter for the 450D.
2. Using the determined length and total amperage draw, consult the wire gauge chart included in this section. Round up to the closest amp draw listed on the left, then round up to the closest length at the top of the chart.

• For example, the 450D heater with six Cozy heat exchangers with the Reporter placed 15 feet from the vehicle’s battery would require an 8-gauge wire.

Wire Gauge Chart:

Fuel Pressure

Extreme Cold Weather Operation

120V AC Electric Element

Please note that the 120V AC Electric Heating Element is the Aqua-Hot’s secondary heat source for heating both the interior and/or the domestic hot water during low heating demand situations (such as when moderate ambient temperatures exist and/or when there is a low demand for domestic hot water). If the 120V AC Electric Heating Element is not providing enough heat, turn the diesel burner ON in conjunction with the 120V AC Electric Heating Element.

Diesel Burner

If the Diesel Burner fails to operate: 

• Determine if the diesel fuel in the motor home is winter or summer fuel
• Verify that the diesel fuel is liquid and not jelled
• Make sure the electrodes are properly adjusted
• Determine when the last annual service was performed
• Check the Reporter for any faults (see Figure 137)

Things to Check for Lack of Interior Heat:

1. Diesel burner must be on
2. Diesel burner operating properly
3. Antifreeze concentration in the boiler tank must be between 30-50%
4. Heating system must be properly installed according to the 450D Installation manual

• At least 5 heat exchangers installed in the interior of the coach
• Must be cold air returns installed for every heat exchanger (reference Figure 139)
• Heat exchangers should be mounted as close to the hot air outlet grill as possible (Figure 138)

Aqua-Hot Maintenance

Monthly Maintenance:

Check the antifreeze and water heating solution to ensure that it is at the proper level by visually checking the solution level in the expansion tank. The level of the antifreeze and water heating solution within the expansion tank should only be checked when the Aqua-Hot is at maximum operating temperature. If additional antifreeze and water heating solution is required, fill the expansion tank to the “HOT” level mark. Reference Figure 140. Be sure to reference page 8 for the type of antifreeze and heating solution. Additionally, it is recommended that the diesel burner be fired and allowed to run monthly to keep it in good working order.

Annual Maintenance:

To keep the Aqua-Hot running smoothly, it is recommended to have the diesel burner tuned up annually or after the coach has been stored unused for a long period of time. A tune-up should consist of a new fuel nozzle and fuel filter, along with a thorough cleaning of the combustion chamber. To ensure maximum diesel burner performance, always use the recommended fuel nozzle and fuel filter when replacing these parts.

Winterizing the Aqua-Hot

The Aqua-Hot’s domestic water heating system must be completely drained of domestic water at any time the heater is stored where freezing temperatures may be experienced. Please follow these instructions when winterizing the Aqua-Hot domestic water heating system. Reference Figure 171 for a system overview.

1. Completely drain the fresh water storage tank.
2. Disconnect the domestic water demand pump suction line from the fresh water storage tank.
3. Attach an adequate piece of hose onto the suction side of the domestic water demand pump.
4. Place the opposite end of the hose into an adequate supply of non-toxic RV winterization antifreeze (FDA certified as “GRAS” Generally Recognized As Safe must be used) and allow the fluid to pump through.
5. Open and close all interior and exterior water faucets one at a time, until ONLY pure RV antifreeze is present. Perform this procedure for both cold and hot water faucets.
6. Remove the hose and reconnect the domestic water demand pump’s suction line to the fresh water storage tank.

De-Winterization

To de-winterize the Aqua-Hot system, completely fill the fresh water storage tank. Open and close the interior and exterior faucets, one at a time, until only clear water is present.

Disinfecting the Domestic Water System

The Aqua-Hot Heating systems contain copper tubing and are not compatible to prolonged exposure to sodium hypochlorite (bleach or liquid bleach). Using products containing bleach, including water refreshers, may cause corrosion of the domestic water lines, resulting in a catastrophic failure of the Aqua-Hot system by creating leaks that cannot be repaired. This damage is not covered by the Aqua-Hot warranty. If disinfecting the hot water system, be sure to follow NFPA 1192 Standard on Recreational Vehicles “Instructions for Disinfection of Potable Water Systems” or any other applicable local standards for Potable Water Systems.

Filling the Aqua-Hot

In order to provide the best freeze protection, boil-over protection, anti-corrosion, and rust protection, a mixture of 50/50 propylene glycol antifreeze and distilled water is recommended. The Aqua-Hot 450D boiler tank holds approximately 5 gallons.

Be sure to use a “GRAS” (Generally Recognized As Safe) boiler-type propylene glycol based antifreeze, rather than a RV and Marine antifreeze or an automotive antifreeze/coolant. Reference the Owner’s manual for additional information regarding the antifreeze and water heating solution.

The mixture may be modified to provide the most adequate freezing, boiling, and rust/anti-corrosive protection. A 50/50 mixture of propylene glycol and distilled water has a freeze point of approximately -34°C (-29°F) and a boiling point of approximately 106°C (223°F).

Fill Instructions:

1. Locate the following items: -Exterior fluid pump (a diagram pump if possible) -The Aqua-Hot fluid expansion tank -A bucket or pale
2. Fill the bucket with the heating solution. Ensure the fluid expansion tank is connected to its port on the Aqua-Hot.
3. Open the Aqua-Hot’s drain valve located at the front of the heater. Reference Figure 173.
4. Connect the external fluid fill pump to the fluid drain valve. A ½” NPT barbed fitting is best for this task.
5. Place the supply line of the external pump in the receptacle that contains the heating solution.
6. Locate the Reporter, and navigate to the “INPUTS FROM AQUA-HOT” page.
7. Pay attention to the “LOW LEVEL SENSOR” item on this page.

8. Fill the tank to approximately ¾ full, or until the “LOW LEVEL SENSOR” item displays “TANK FULL”, approximately four gallons.
9. Once the tank is partially full, deactivate the external fluid fill pump and close the drain valve. DO NOT disconnect the fluid pump.
10. Proceed to the next page to purge the zone before attempting to start the unit.

Purging the Interior Heating Loop

In order to provide interior heat to the vehicle, antifreeze and water heating solution is circulated within an interior “heating loop” which distributes heat throughout the coach. During installation or service, it is possible that air may become trapped within the heating loop and hamper unit performance.

Follow this procedure to purge any air from the interior heating loop.

Please note that if an RV-C or multiplex system is used in lieu of the Aqua-Hot display, you must contact the manufacturer, or connect a display to the on-board RV-C network to perform this procedure.

Purge Procedure:

1. Locate the fluid expansion tank of the Aqua-Hot. As any air is purged, it will exit through to this expansion tank.
2. Locate a gallon of glycol antifreeze. This will be used to top-off the fluid expansion bottle as air is purged from the system.
3. Navigate to the “PUMPS” page of the “TESTING” section on the Reporter as displayed below.

4. Tap each of the pumps to independently activate them, beginning the heating loop purge procedure. These pumps will remain active for a maximum of 5 minutes. They will need to be reactivated as needed until the purge procedure is complete (at least 20 minutes).
5. Continue to fill the unit as air is purged from the interior heating loop.
6. Once the air is no longer returned from the heating zone return ports, deactivate the fluid circulation pumps.
7. Open the fluid drain valve, and activate the external fluid fill pump. Fill the unit with GRAS propylene glycol antifreeze and water heating solution until it reaches the “COLD” mark on the fluid expansion tank.

Draining the Aqua-Hot

Drain Procedure:

1. Connect a piece of ½” PEX-type tubing or rubber hose to the drain valve. This piece should be long enough to transport the antifreeze and water heating solution from the Aqua-Hot to a bucket.
2. Open the Aqua-Hot’s drain valve located at the front of the heater. See Figure 173.

System Schematics