Water tank syphoning?

[serenisea]

I hope Peggie Hall still has her ears on for this one....We now have a Seawind 1160 catamaran. Recently, we have been having issues of the forward vanity under the sink filling up with water and then spilling over into (thankfully) the shower sump, which makes up the sole of the head. I thought is was rain catching somewhere coming down the mast, as it did not do this when we wash the boat.

I had the boat yard replace the faucet on this vanity, and it is now even worse. But this time, no rain, and even though the fresh water system was switched off, there was a reduction of about 25 liters of water from the water tank, and the head sole was absolutely flooded. I was able to look inside the vanity, and saw drips coming off of the pex fittings that couple to the hot, cold and diverter to the faucet (not sure which one, because they are clustered together).

I ran the faucet with the switch off to create an air gap and will check it tomorrow. The water tank is under the setee, and the vanity is up higher. Both are above the water line. So I am suspecting that the water tank vents may be clogged with spider webs or swallow nest mud, both of which we get a lot of in the summer time in the Sacramento River delta. I have reached out to the builder to confirm the location of the tank vents.

Thoughts?

 

[rgranger]

with pex, it would be easy to add a shut-off valve. You should still run down the problem but a shut-off would add a layer of safety.

 

[JamesG161]

Turn off the power to the water pump, until you find the water pipe leak.

Jim...

 

[JamesG161]

The water tank is under the setee, and the vanity is up higher. Both are above the water line.

No siphon is possible.
_____

So I am suspecting that the water tank vents may be clogged

If clogged, no water pumping is possible.

Jim...

PS: Seawind 1160 | Seawind Catamarans - Catamarans For Real Sailors

 

[Peggie Hall HeadMistress]

I hope Peggie Hall still has her ears on for this one...

I do...but fresh water plumbing isn't in my wheelhouse, so I wouldn't be much help to you. However it looks to me that you're getting good suggestions from others so I'm paying attention to this conversation hoping to learn something.

--Peggie

 

[serenisea]

With regard to James, he missed it in my original post that this all happened after I shut off the water at the panel.

 

[rgranger]

I feel like we are missing something. If the pump is off and the line depressurized, then there should be no way for water to move uphill from the tanks. Are you connected to shore water and the pressure from the hose is pressurizing your system? Are you sure the water on the floor of your head is fresh water? Maybe a few more pics of the situation would help us figure this out but from the info we have... I feel the situation does not meet up with the known facts.

You said there is water dripping off the lines leading to the faucet. What happens when you open the faucet? Does water come out? If so, then you are not dealing with a depresurized system.

 

[JamesG161]

this all happened after I shut off the water at the panel.

I know that.

Turn off the power to the water pump, until you find the water pipe leak.

Then fix your leaking pipes or leave the power off your pump.

Jim...

 

[serenisea]

OK-Here is what I found tonight. The water pump was shut down over night again as usual, with the faucets turned on afterwards to drain any water away from the faucets and create an air void in the water system. Not only was the shower sump and the vanity full of water again, I got a picture of the cold side pex fitting under the sink dripping at a pretty good clip. The water meter showed a loss of about 70 liters of fresh water during the 24 hour period. I turned that faucet on during the process, but nothing came out. So something was syphoning but getting out due to a bad connection with the faucet supply line.

If there was a break in the pex line lower than the tank, I could understand that would create a syphon. But I believe the area under the vanity must be higher than the tank, so I do not understand how the water gets that high. Will getting a good seal on the pex fitting stop it, I will let the boat yard that installed the faucet last month fix that? But it seems like with everything shut down, there should be no water movement anywhere. I am with RGranger on this, in that it should not be happening.

I turned on the pump and the faucets and drained the tank down to about 75 liters of water (from about 225), and the dripping stopped. I pulled out the medicine chest, to get a better look at the pex fittings behind the wall, and there was nothing wet above the fittings for the faucet supply lines. I will check it again tomorrow. Maybe the tank water level will shed some light on the situation.

 

[Davidasailor26]

When the pump is on does it periodically cycle? 70 liters per day is a remarkable about of loss for a depressurized system. If there were a leak that significant I would expect it to really loose a lot when pressurized.

 

[serenisea]

David, It does do a quick cycle on occasion when pressurized. After I turned off the faucets to drain the tank down, it did one quick (1 second) cycle in the remaining half hour I was there before shutting it down. I did not check the pex again because it was getting late. A pressured up leak like I saw, would normally lead to an intermittent pressure priming attempt by the pump on the scale of about every couple of minutes.

Assuming it is a syphon, then the pex screw on coupling I am guessing must be shot to allow a non-pressurized leak to dribble, and not a pressured up situation. Just doesn't make sense. Will check again tonight, but have more time tomorrow to look at it.

 

[Davidasailor26]

Just doesn't make sense

Could there be some other plumbing in the same area that’s actually dripping on the pex you see? Maybe the fill or vent line, or a hose on the unpressurized side before the pump?

 

[TimFromLI]

Is your hot water tank higher than the vanity?

 

[rgranger]

There is no way to siphon up hill you can’t be having water dripping out of your pex if the pex is above the tank. If The water on the pecks is coming from the tank than it must be pressure pushing it up there

 

[serenisea]

The tank is now totally siphoned out. Last night I did some approximate measurements, and I now believe the vanity is slightly lower than the water tank. So that probably explains it. To answer Tim, the water heater is lower than the tank, and I remember having to drain the tank to replace the water heater drain valve when it started to leak. So I think I have my answer. The last remaining question is whether the pex coupling has become defective, because this started before I had the yard replace the faucet. I will ask them to put on a new one to make sure.