Re: Fresh water tank overflowing on city water
Hi Larry,
It might be the valve, and the valve is pretty easy to change. It's also possible to replace just the cartridge in the center of the valve. And you can probably call either Heartland or Anderson and they'll likely send you a replacement at no charge for self-install.
But it's more likely to be the internal check valve in the water pump is stuck open, allowing water to flow backward through the pump. If you have a good hardware or a plumbing supply store nearby, for about $15 you can pick up a 1/2" push-on Sharkbite check valve. In a couple of minutes you can install it on the suction side of the pump and that'll probably take care of it. Make squared off cuts to the tubing and be sure to look at the arrow on the check valve so you get it pointing in the direction of normal water flow.
If you want to spend a few minutes testing things first, you could disconnect the hand-tightened fitting on the suction side of the pump to see if water is coming out there. You can test the valve by disconnecting the fitting that goes to the pump to see if water comes out there.