Motorized City Fresh Water Tank Fill Valve with Automatic Fresh Water Pump Control

Like many Roadtrek RV models, the RT Agile has two options in getting their fresh water tank filled, either via gravity fill port located on passenger side door B-pillar or via the city water hookup. I mostly use the city water connection just because it is on the same side where the macerator dump is, and most dump stations/ campgrounds are set up this way. 

Filling the fresh water tank via city water hookup involves few steps and this mod drastically shortens those steps. To fill the fresh water tank, all I have to do now is flip a switch then hookup the city water…and that’s it. No more walking around the RV, opening the sliding door, reaching and manually opening the fill valve, then doing same process in reverse once the tank gets full. 

The motorized fresh water tank fill valve will be integrated into my hot water automatic recirculation system (posted here) to prevent or minimize the freshwater line from freezing during below freezing weather conditions. Details will be in my future post.

[Wiring diagram]. When the fill valve is switched on, a secondary relay disconnects the water pump thus turning it off and vice versa when the fill valve is switched off. 

The system does not consume power when on standby, it only draws very little during switching and while the valve is open (relay draw). An inline manual valve is installed in an event that the motorized valve fails to close. The original quarter turn valve is still operational and will be used as a backup.

List of items/tools used: (To open Amazon link in new tab, right click link and select open in new tab)

• (x2) 1/2" NPT to 1/2" PEX 90 degree elbow fittings
• (x4) 1/2" x1/2" PEX 90 degree elbow fittings
• (x2) 1/2" x 1/2" x 1/2" PEX Tee fittings
• (x1) 1/2" PEX quarter-turn ball valve
• Motorized Ball Valve with 1/2" NPT female connectors
• PEX cinch clamps
• PEX cinch clamp tool
• Wire crimping tool for insulated/ non-insulated terminals.
• Illuminated On-Off switch and Switch base/ Face plate (available for single or multiple switches)
• 3-conductor 18-AWG cable
• 3-pin waterproof quick disconnect
• (x2) 5-Pin Automotive relays
• Crimp type barrel connectors, male and female pairs
• Optional heat shrinks
• Wire cutter/ stripper
• Soldering iron

[Factory city fresh water fill valve in an open position.]

I use a Dremel tool to remove the old PEX cinch clamps, I cut the clamp ears then just pry the clamp off the fitting. A PEX cinch clamp removal tool is a good investment if you will be doing lots of PEX work.

The motorized valves, manual shut off valves, and the fittings were pre-assembled before finally attaching the two Tee fittings into the PEX pipe inlet and outlet fresh water tank fill connections.

Because of the limited space where the fill valve is installed, I had a hard time installing the clamp for the inner brass Tee fitting. There is not enough space for the cinch clamp tool to fully open its jaws, I ended up using a bullnose pliers cutting jaw to pinch the clamp ear...it did work but I had to exert lots of force on the plier handles to really cinch the clamp tight.

With everything connected. Next is wiring.

[With the over the sliding door switch panel removed]. The 3-conductor cable was fished above and behind the rear bathroom wall> then down into the bathroom pull-out sink area> then into the passenger ottoman base cabinet before finally exiting into the motorized valve location.

 

The automotive relays were mounted on the back of the switch panel. The 2-conductor switch wire is routed into the driver side overhead cabinet via the headliner (refer image#1 above for wiring schematics).

[Driver side overhead switches.] To "dump and fill", all I need to do is toggle on both macerator and city water switches...empty the holding tanks then connect the city water line. The macerator switch above is for the wireless macerator controller (posted here).