Monday, January 31, 2011

Water Accumulator Tank

Note: This is a user mod, not standard on Lazy Daze

Water pumps and attaining a "good" consistent flow of water are a constant source of discussion. Water pumps, which will be covered in a separate FAQ, provide a flow of water that pulses as the pump turns on and off in response to the water demand. To address the pulsing water flow, a few LD'ers have installed accumulator (expansion) tanks in an effort to smooth out the flow. Here are comments from two:

- I have been having problems with my water heater.... No, it heats water OK, but when it does, I have to keep a close eye on it or the pressure builds up until the relief valve lets go and water runs down the side of the trailer. After reading about using an expansion tank to fix this problem, and pricing the Shur-Flo tank in several RV sources, I found a cheaper answer. I went to a local Home Depot, and for $35 I bought a 2 gallon water heater expansion tank. I found room for the tank behind a drawer under the dinette seat. Add a brass fitting or two, a stainless flex hose and a standard PVC compression tee.
Probably the neatest thing about using an expansion tank is the way your water system works: I pre-charged the tank with 30psi and then turned on the pump. The pump ran for 30 or 40 seconds and filled the tank. Then, you can use the water for a surprisingly long time before the pump runs again. The water pressure is higher and more consistent, and I find that I can flush the toilet several times and wash my hands, etc. before the expansion tank is emptied. And my water heater no longer gives me any problems.

- I did some testing, identified an overpressure condition that was causing my pump to leak, and installed an accumulator tank. That addressed the overpressure condition. Twice since then, my pump has heated up to the point where it cuts off. A period of no power to the pump to allow it to cool down results in its return to normal operation.
I don't KNOW that this is related to the installation of the accumulator tank, but I don't know that it is not. The tank is charged to 80 psi, so the pump should not "see" the tank in the system. Still, it might be related to what I did, so I wanted to make all aware lest you try an accumulator tank and burn out your pump.
Contributors: Mike Richmond, Ken Fears
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