Galley pump runs ONLY when water heater on?!?!

diggin2day1

Okay, here's a weird one that I just can't figure out: 
My galley pump will come on in short bursts or pulses(almost like there was a leak or a faucet slightly open) ONLY when we have the breaker on for the water heater. There are no leaks in the system, the water heater drain is shut tight and the bypass is closed. It doesn't happen immediately, only after a few hours of the breaker being on. 

More info: 2002 FV270, all faucets are shut tight(galley sink, bathroom sink, cockpit sink and transom shower), brand new galley pump installed last year(because I had this problem and thought that was the solution). 

Ideas: are there back flow valves on the lines leaving the water heater? Could that be it? Any other ideas

Black_Diamond

Could be swelling of the hot water lines or an internal leak with the hot water tank thru the heat exchanger with the engine.

diggin2day1

It's driving me crazy... It's been acting real wonky... On some occasions when I turn on the cold water, I'll get a quick blast of hot and then will go cold and stay cold. 

MarkB

First can you check that you have 13V at the pump when you turn on the galley pump but have the heater OFF.

I suspect you have power and this is simply related to the water getting hot and you have a blockage somewhere in the lines.

Check strainer, and follow lines as much as you can to determine what shape they're in. There's a non return valve to check as well and inspect the faucet, they have a strainer on the end as well.

diggin2day1

MarkB- I'll give it a shot... Where would the "non return valve be? And as for each faucet, are you talking about the water diffuser where the water comes out? 

MarkB

The non return should be between the pump and where your shore water supply comes in (where you can hook up to city water).

Yes I'm talking about the diffusers.

diggin2day1

Hmmmm, I have no city water hookup... Just a fill hole for my freshwater storage tank. I'm heading down to the boat in a little while to do some more trouble shooting, and look for filters, diffusers, leaks and gremlins. 

raybo3

Is it possible that the hot water heater safety valve is blowing by when the water is getting hot........

Cableguy Greg

raybo3 said:

Is it possible that the hot water heater safety valve is blowing by when the water is getting hot........

That's what I would think is happening.

diggin2day1

I was down there today and all strainers and diffusers were clean and there's zero leaks. Took a few pictures of the water heater... Going to call the company and see if they can help me troubleshoot it. 

MarkB

With the pump on can you pull the safety valve nozzle up and see if it's full of air or whether water comes out.

Note that when you start your boat after winterization this tank will be full of air and should be releaved through the safety valve to get rid of all air.

howardrams

Yes definitely run lots of water through the sinks through the hot water faucets and/or bleed out any air through relief valve on the hot water tank.  You want it 100% water, no air in there or it can turn to steam and make all kinds of weird things happen.  Though the galley pump should turn on and run whether the water heater is on or not when you open a cold faucet.