City H2O filling fresh tank

[TXTiger]

I have a 2012 Cyclone 4014 purchased new over 4 years ago. I fill the fresh water tank with a garden hose at a separate hookup from the city water hookup. When using city water I connect the garden hose to the city hook up. The tank and the city supply are independent from each other. To use my fresh water tank water I turn on the power to the water pump. To use city water the pump power is off and I just turn on the faucet. My fresh water tank keeps filling up on its own even with the pump power turned off and overflowing out the fill spout. Not sure what is supplying the water to the tank. The only water hooked up is the city connection. I do not have a switch between the tank and city supply that I know of. I now have the city water turned off at the faucet and am using the pump and tank water. How is the fresh tank filling up from the city connection?

 

[danemayer]

The water pump has an internal check valve that is supposed to ensure water flows in one directly only. It's stuck open allowing city water to flow backwards through the pump into the fresh tank. There are 2 ways to fix it. 1) replace the pump. 2) add a check valve on the suction side of the pump.

You should be able to find a push-on Sharkbite check valve at Home Depot or Lowes.

Page 11 of our owner-written Water Systems Guide has a drawing that illustrates the problem.

 

[TedS]

The city water and pump output connect to the same cold water plumbing. The water may be passing backwards through the pump. There are check valves on each of the pumping chambers. There may be debris keeping one or more outlet check valves open. It is relatively easy to remove several screws that hold the pump head together and clean the valves.

 

[TXTiger]

Thanks for all your replies. I just replaced the pump about 4 months ago. I will have to see if I can take it apart and clean the valve. The original pump was replaced after 2 years and the replacement pump only lasted 2 years. This new pump is only 4 months old.