Pressure relief valve on hot water cylinder

[john daley]

We've just come back from a trip where we have had problems with water coming through the pressure relief valve and emptying hot fresh water into the bilges. We had a similar problem last year where there was an engine overheating problem and the water was getting excessively hot but that was resolved and is not the cause. It is also a problem because it uses up battery power as the water pressure pump keeps topping the tank up.( I now keep the water pressure switch off) This only seems to happen after the engine has been running for a while and the water is heated up.  I have tried flicking the valve open and shut in the hope that there was a bit of dirt stuck in the valve, but to no avail. Can I remove the valve without losing water everywhere. Is there a valve to turn off the water to the cylinder, or is that controlled by the regular valves from the water storage tanks? Any help appreciated.

[Ted Pounds]

I've never replaced the valve on my boat but I recently did the valve on my home water heater.   I believe they're basically the same type of valve.  They do just fail after a while.  Just turn the water pressure off(shut off the pump) and you'll only dribble a little water.  Also It's best done with the water cold(i.e. turn the heater off too).  I'll bet you can get a replacement valve at the local hardware store. Put some teflon tape on the threads for a good seal.  Good luck.

Ted

[dsavary]

The rule of thumb on hot water relief valves is, that you relace it if it has been activated from a prior incident. Yours is probably opening prematurely after your first event. This can be easily check by measuring the temp of the water coming out of the valve when it opens with a candy themometer.  Most often relief valves dribble after openning and never reseal. You must replace it with and exact replacement temp valve, 5 degrees either way makes a big difference.

[mike baker]

After you turn-off the freshwater pump be sure to bleed-off the pressure in the system by opening the galley sink faucets before you try to remove the old pressure valve. If you don't you might get a face full of very hot water.

Mike Baker #815 "Gray Hawk"

[john daley]

Thanks for all your help, guys. This facility is just fantastic. I post a question, go to bed and wake up in the morning  with a couple of answers waiting for me!!
Anyway, I've taken your information on board and I'm working on it. thanks again.

[sail4dale]

Found out I didn't have a problem with my fresh water pump cycling but a leaking relief valve in the water heater.  Called Seaward, talked to service and they are sending me a replacement at no charge.

Wow! what a great service attitude.  Nice to see in a manufacturer now-a-days.

[hdevera]

I had the same or similar problem in my 2001 Catalina 34.  The one way valve broke in half.  It was plastic.  I replaced it with a metal valve from West Marine.  Haven't had a problem since.  If Seaward sends you a plastic vavle, i'd place it aside and buy a metal one!

[sail4dale]

The relief valve is just like your relief valve on the water heater at home.  

I am told by the Manufacturer Seaward, that it will unscrew with a pipe wrench.  It has pipe fittings on it, and replace it with a new one available from Seaward.

Call them and they will send you a new one ... maybe for free?  They did for me.

Turn off the pressure, open the sink valve to relieve any residual pressure, and unscrew the relief valve.  That's all you have to do.  Good luck.

sail4dale #1582 True Luff