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Old 08-13-2022, 04:32 PM   #1
2 Rivet Member
steve0white's Avatar
1976 Argosy 28
2021 27' Flying Cloud
Grand Rapids , Michigan
Join Date: Jul 2013
Posts: 27
No Drill Diverter/bypass for Tankless Hot Water

I think the complaints on the Girard Hot Water heater have been well documented. The solutions seem to be 1) shower miser flow diverter/bypass (which involves drilling holes in the shower) 2) Replace with Truma (tankless) or Suburban SW6DEL (tank) 3) deal with the wasted water or collect it in a can 4) only camp with full hookups

I installed an automatic diverter system that doesn't require drilling holes in your shower. I used a flow switch (NC), solenoid (NC), a couple of tees and hoses. The system is powered by wiring into the shower light. So it is only active when the shower light is on.

Flow switch is Normally Closed and is installed on the hot water line of the shower. Normally closed means the electrical switch is closed when no flow detected and open when flow is detected. When shower valve is open, flow is detected and power is cut to the solenoid, no water bypasses to FW tank. When shower valve is off, solenoid is open allowing water to flow to the bypass back to FW tank.

There is a tee with a valve on it before the Flow Switch. This connects to the solenoid and back to the freshwater fill line with another tee.

  • Flow Switch: GEMS FS-150 NC 0.5GPM
  • Solenoid: Using an adafruit one, but trying to find one rated food safe
  • Tee for hot water line: SharkBite Brass 1/2-in PEX Barb x 3/8-in OD Compression Quarter Turn Supply Stop
  • Tee for Fill: Reducing Adapter Tee: 1 1/4 in x 1/2 in x 1 1/4 in Fitting Pipe Size
  • Pipe/Hose: I used braided stainless steel hoses to connect the tee to solenoid and solenoid to fresh fill
  • Adapters: Pex to 1/2" female pipe to connect to Flow Switch and 1/2" male pipe to 3/8" compression and a 1/2" female to 3/8" compression to match up with the hoses I had on hand
  • Hose clamps: for fresh water line

  1. Cut section of pipe and insert flow switch
  2. Cut section of pipe an insert tee (between switch and pump)
  3. Cut freshwater line and insert tee
  4. Connect pipe tee to solenoid is hose, connect other side of solenoid to fresh water fill tee
  5. Find switched purple line for the shower light
  6. Wire the light wire to one side of the flow switch and the other side to the solenoid. Ground the solenoid. I used Wago connecters and used the pump ground.

  • This works pretty well for the 4 of us and allows us to take Navy showers without getting the cold water sandwich or wasting a bunch of water
  • This installs without needing to drill holes in the shower. Just turn the light switch on and watch the Girard controller to see when it is hot.
  • Seems to work better on pump than on city water. Sometimes the flow switch won't open when turning the shower back on when on city water
  • You'll need to adjust the valve to make sure that the flow switch gets triggered
  • Make sure to shutoff shower by turning the handle all the way to off or installing a second shut off. Using the pause on the showerhead allows cold water to trickle through.
  • You can use this to fill FW tank with the hot water heater off
  • check materials so they are safe to be used with potable water
  • make sure to disconnect or blow out for winterizing
  • you could use this for continuous hot water when doing the dishes in the sink, you just won't have full flow since the bypass will be always open
  • you could change the location of the bypass tee and switch to work for both the sink and shower
  • Propane and pump run while the shower light is turned on, so kind of defeats the purpose of the on-demand system
  • Parts ran <$200, most expensive piece is the flow switch. I got through Grainger, but looks like Zoro might have better prices and Omega Engineering may have cheaper alternatives
  • I tried installing a recirculation loop that had a pump an connected the shower line back to the hot water heater. This failed. It just overheated the system causing the heater to shut off. Kind of a bummer. Might work better with a storage tank, but then why not just put in a tank system
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