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bobcovey · 11-23-2014, 02:51 PM

2003 Executive 43 SDDS2: Five days or so after emptying the fresh water tank, water starts dripping out of the tank overflow. Opening the tank drain valve immediately stops the leak from the overflow. The tank monitor confirms that the tank is full, but that system isn't completely reliable. We have been hooked up to city water the whole time.

I suspect that the city water fill valve is beginning to fail, allowing water to slowly fill the tank. Is it that simple or is there more to the system than that? Am I missing something else?

I don't have a plumbing diagram. If one exists, I'd be grateful for a copy.

Cheers,

falconman · 11-24-2014, 09:58 AM

It either that or the check valves in the water pump have failed or picked up some debris allowing water from the city source to backfill into the FW tank. If there is a valve between the pump and the FW tank you can close it to see if the problem stops. If not, clamp the line temporarily. It that's the issue you might be able to repair the pump if you can get the pump head apart. If it's an original one it might be best to replace it.

Chaffeekid · 11-24-2014, 10:27 AM

If you have an outside shower, check that both valves are OFF. if they are left on they can allow city water to fill your tank. Can also prevent your water heater from getting hot as it will mix the hot and cold water. What happens is the shower head is turned off but the valves are left open.
Check it.

bobcovey · 11-24-2014, 04:41 PM

Thanks for the suggestions. There is a clear plastic device on the input side of the pump, between the pump and the shut off valve on the line feeding it. Is that the back flow valve or is it buried somewhere in the tank compartment?

No outside shower, and the inside shower does not have a shut off between the main valve and the showerhead, so I think I can rule that out.

Cheers,

Mike Canter · 11-24-2014, 05:17 PM

That is a strainer on the input side of the pump. I believe the one way valve is integral to the pump. The other thing to check is that ball valve that you turn to fill the tank. Maybe that is leaking.

nothermark · 11-24-2014, 05:29 PM

FWIW I would be inclined to switch to the pump long enough to really flush out the valving in case all it is is a bit of debris in the wrong place. Maybe before showers is a good time as it gets a couple of minutes of run time.

mccrob · 11-24-2014, 09:29 PM

Had the same problem changed the Swan valve twice but the problem was the pump valve failed and let the water to back flow to the fresh water tank shut the valve between the pump and fresh water tank problem solved

bobcovey · 11-24-2014, 10:11 PM

Ok, it sounds like I have more detective work to do.
We'll be staying in one place in December so that will give me time to explore this at length.

Thanks for the suggestions.

Cheers,

arby · 11-25-2014, 09:29 AM

I had the same problem on my 07 Diplomat. Turned out it was the city/fill valve. Gave up trying to find exact replacement at big box stores and finally ordered from Monaco. Pretty expensive (around $100 as I recall) but saved a lot of frustration. Fairly easy to replace IF you can get to it.

bobcovey · 11-29-2014, 10:50 AM

Just to put closure to this, operating the city water fill valve 15-20 times appears to have cleared whatever was causing it to leak into the tank. After three days the tank is still empty.

Cheers,

ShapeShifter · 12-05-2014, 03:27 PM

Quote:

Originally Posted by Chaffeekid

If you have an outside shower, check that both valves are OFF. if they are left on they can allow city water to fill your tank.

I'm having trouble picturing how this could happen. Leaving the hot and cold valves on while the shower head is turned off can connect the hot and cold lines, thereby diluting the hot water and making it not as hot, but how can it possibly back feed into the fresh water tank?

The only mechanisms I can think of are the already mentioned pump (most common) and the city water diverter valve (less common.) Good to hear that the OP figured it out and it was an easy fix!