Leaking hot water tank’s pressure relief valve

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Lshulan

Lshulan

Senior Member
Joined
Jan 10, 2022
Messages
155
Vessel Name
Voyager
Vessel Make
Mainship 390
On my 2002 mainship 390, the pressure relieve valve on the hot water tank has a slow drip. It appears to just be screwed in, anyone have any experience in removing and replacing one? I’m concerned I’ll wreck the tank if I puts a big wrench on it and break something
 
That is always a concern. Be gentle. Upon re-install, use some kind of non hardening pipe dope with teflon. It will prevent galvanic corrosion with dissimilar metals.
 
Mine came out easy and new one installed.
If it does not unscrew easily, tighten then unscrew, rinse repeat
 
Thanks to both of you, will give it a try when I get back to the boat. But one other semi related question, is there an anode in the tank and if so, how to get it out for replacement. Ideas? Experience? Are both the relief valve and anode standard items?
 
You might spray some corrosion lubricant on the threads a couple of days before you try to take it out. If it doesn’t want to come out try some heat with a heat gun. Some have anodes some don’t.
 
Have you tried working the valve repeatedly—I mean really going at it for a while? I had a slow leak from a sticky valve that I fixed that way.
 
Agree with working the valve.
Raritan hot water heater has an anode. Your results may vary.
 
Are you sure where the drip is actually from?

If from the threads, should be an easy fix of proper thread sealant and normal tightening.

If from the actual release... if your water heater is in the engine coolant loop, occasionally the engine temp gets high enough to create high enough pressure to cause the drip. Not sure if there are release valves that are a bit higher, might be NOT the right thing to do as it is an engineering issue at that point.

One thing you could try is (and there should be one anyhow) is have an inline valve in the coolant line to minimize or stop the coolant to see if the leak stops and then just use it when the leak starts and open it maybe just a 1/2 hour out of your destination if you think you will need hot water before heating the tank with electricity.
 
psneeld said:
Are you sure where the drip is actually from?

If from the threads, should be an easy fix of proper thread sealant and normal tightening.

If from the actual release... if your water heater is in the engine coolant loop, occasionally the engine temp gets high enough to create high enough pressure to cause the drip. Not sure if there are release valves that are a bit higher, might be NOT the right thing to do as it is an engineering issue at that point.

One thing you could try is (and there should be one anyhow) is have an inline valve in the coolant line to minimize or stop the coolant to see if the leak stops and then just use it when the leak starts and open it maybe just a 1/2 hour out of your destination if you think you will need hot water before heating the tank with electricity.
Click to expand...
If that turns out to be an issue, it's also possible to add an expansion tank to the hot water side of the system (after the inlet check valve on the water heater) to reduce pressure increase as the water heats.
 
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