How do I fix or replace the fresh water tank fill / city water selector valve in the wet bay?
Fixing or replacing the fresh water tank fill / city water selector valve (sometimes called the “Anderson valve” or “diverter valve”) in your Tiffin’s wet bay is a straightforward but critical repair. Here's what you need to know:
🔍 Problem Symptoms
- Water only flows to the tank or the city line—not both when switched
- Water leaks from the valve or behind the wet bay wall
- The handle feels loose, cracked, or spins freely
- Valve is stuck and won't turn
🛠 Tools & Supplies You’ll Likely Need
- Replacement valve (commonly a 2-way or 3-way brass diverter or Anderson valve)
- Adjustable wrench / channel locks
- PEX cutter or tubing cutter (if lines are crimped)
- PEX fittings or SharkBite connectors
- Teflon tape (for threaded fittings)
🔧 Step-by-Step: Replace the Selector Valve
- Shut off all water
- Disconnect from city water and turn off your water pump.
- Open faucets to relieve pressure in the lines.
- Access the valve
- Open the wet bay panel. If necessary, unscrew and remove the rear service panel to expose plumbing behind it.
- Label or take a photo of the lines so you remember which goes where.
- Disconnect the plumbing
- Use a PEX tool or release fittings carefully.
- If SharkBite fittings are present, press the release collar while pulling the tubing out.
- Remove the old valve
- Unscrew or unclip the valve from its mounting.
- Check for any broken internals or stripped threads.
- Install the new valve
- Reconnect all plumbing using either PEX crimp, SharkBite, or hose clamps (depending on original setup).
- Wrap threaded fittings with Teflon tape to prevent leaks.
- Secure the valve in place.
- Test for leaks
- Slowly turn the water back on (pump or city water).
- Test both modes: Tank Fill and City Water.
- Verify that pressure and routing work correctly and there are no drips.
⚠️ Pro Tip:
- Tiffin often uses color-coded PEX lines and standardized valve types.
- If yours is cracked or failing regularly, consider upgrading to a brass diverter valve if it's a plastic model now.