After not being used for a six month long winter, the T&P relief valve on a approx. ten years old, 6 gallon Seaward
heater started leaking less-than-lukewarm water
after working for about five to ten minutes.
Due to the lack of an expansion tank, I assumed the T&P relief valve was due for replacement.
The valve Seaward
provided with this water heater is set at 150 psi (about 10 bar) and 210°F. Replacement Seaward valves are available in abundance in the US, but here in Europe
there are none to be find. So instead of waiting (and paying, excessively) for the valve from overseas, I figured I'd try and find a similar valve closer to home.
After a little research
and visiting a number of stores, I found that the only conventional valves sold here are 'simply' pressure
relief valves and are set for 4 bar (about 58 psi). I even got a few chuckles from store employees I showed the Seaward T&P relief valve to, claiming never to have seen one used on a marine
The confusion, I think, is justifiable. If the point of having a relief valve is to relieve the tank from excess pressure caused by the heating (and expanding) of the water inside, why would you want it to open at both a set pressure buildup and a set water temperature? So why would you nead a T&P relief valve instead of 'just' a pressure relief valve on a small marine water heater?
Anyway, I decided that installing a valve with a significantly lower psi set at the very least wouldn't blow up the boat. So I hooked up the 4 bar pressure relief valve, fired up the water heater and apart from the occasional drip, seems to be doing fine. I have yet to run the engine
for a while, so I guess that would be a more revealing test.
If anyone has any thoughts, please share. Also, answer to the prying questions above would be much appreciated!
Thanks in advance.