[hl0m4n]

i had a new boiler installed in 2015.

when the pressure relief valve started leaking water, i replaced it with another. the leaked stopped for a day and came back.
thinking i got a faulty valve, i replaced it again with a new one. no leaks for a day and came back.

late in night, when water isn't used much, the valve is going from a leak to a constant flow of water. enough to fill a 5 gallon bucket in 3-4 hours.
the valve is making a loud hissing sound as the water is coming out. the water does stop when i push in the valve stem but shortly opens up again.

at night i have been turning off the hot water pipe feeding into the boiler and turning it back on in the morning as this stops the leak.
at this point, i believe the valve is doing the job and relieving pressure but what is the issue? any plumbers in here .

[upstatedoc]

call a plumber forchrissakes

[DETRoadster]

Define "leaking." Leaking as in water is coming out where its not supposed to (like past a seal or a joint). Or "leaking" as in it's doing it's damn job and keeping your boiler from exploding?

Agreed with upstatedoc - Call a damn plumber. The fact that you are replacing parts yourself tells me own your place and don't rent. The fact that this is a BMW forum and not a Kia forum tells me you can afford the $100 plumber call to keep your house from exploding.

[byroncheung]

maybe pressure is really too high? do you have a read on what's the pressure?

if pressure is too high, here are some possible reasons:

- if there is a autofeeder, maybe autofeeder / autofeeder valve is faulty and keep feeding in too much water
- the expansion tank not working properly to absorb the pressure when the water is heated up

but i agree with the above - if you need to ask, you should get a heating/cooling guy to have a look at it...

[ToddBlack88]

Two things can cause the relief valve to discharge. The auto feeder failing to lock up/shut off, or the expansion tank is flooded/failed.

If you shut the auto feed off and it stops leaking completely, even when it fires up, then that is your issue. If the valve only leaks when the boiler is firing, then the expansion tank is the problem.

25yr plumber/gasfitter/restricted electrician

[eluded]

Turn off.

#greendeal

[byroncheung]

Originally Posted by ToddBlack88

Two things can cause the relief valve to discharge. The auto feeder failing to lock up/shut off, or the expansion tank is flooded/failed.

If you shut the auto feed off and it stops leaking completely, even when it fires up, then that is your issue. If the valve only leaks when the boiler is firing, then the expansion tank is the problem.

25yr plumber/gasfitter/restricted electrician

sorry for thread hijacking - but i do want to ask, in my setup (have a navien tankless boiler), when the boiler isn't heating, pressure is about 13-14psi. when it heat, it would goes up to the twenties, say 22-23 etc. is that amount of increase normal or i need to have a look at my expansion tank?

[upstatedoc]

i think todd should create "ask a plumber anything" thread

[ToddBlack88]

Originally Posted by byroncheung

sorry for thread hijacking - but i do want to ask, in my setup (have a navien tankless boiler), when the boiler isn't heating, pressure is about 13-14psi. when it heat, it would goes up to the twenties, say 22-23 etc. is that amount of increase normal or i need to have a look at my expansion tank?

Does it stay at that pressure for a bit after it stops firing and the pump shuts off, before dropping back down, or does it drop as soon as the pump shuts down?

I ask because i have found most tankless setups pump into the boiler, and with the large pressure drop design of a tankless system for efficiency, the pressure spikes within the boiler. So thaTs pretty normal.

If the pressure slowly drops back down between firings, then most likely the air charge of the expansion tank is low. I like to set the air charge at about 90% of the static , at operating temperature, system pressure. So if you have a 3 story house with the boiler in the basement, you need a system pressure of about 20psi read off the boiler gauge, when the lines are all up to temperature. Set your air charge to about 18psi.

Every system is different as some may run auxiliary heat exchangers to save the boiler if there is various plastic pipes like poly b in the system, or if the boiler does both heating and domestic generation, as well as the pressure maximum design of the exchanger in the boiler.

[byroncheung]

Originally Posted by ToddBlack88

Does it stay at that pressure for a bit after it stops firing and the pump shuts off, before dropping back down, or does it drop as soon as the pump shuts down?

I ask because i have found most tankless setups pump into the boiler, and with the large pressure drop design of a tankless system for efficiency, the pressure spikes within the boiler. So thaTs pretty normal.

If the pressure slowly drops back down between firings, then most likely the air charge of the expansion tank is low. I like to set the air charge at about 90% of the static , at operating temperature, system pressure. So if you have a 3 story house with the boiler in the basement, you need a system pressure of about 20psi read off the boiler gauge, when the lines are all up to temperature. Set your air charge to about 18psi.

Every system is different as some may run auxiliary heat exchangers to save the boiler if there is various plastic pipes like poly b in the system, or if the boiler does both heating and domestic generation, as well as the pressure maximum design of the exchanger in the boiler.

i *think* it drops pretty quickly. i don't think i have observe it long enough to see it drop when the unit on - but i def have noticed when i shut it down down and restart it, the starting pressure will be the 13-14psi right away.

i only read the psi from the display of the boiler, there is no pressure gauge in the my pipes. i'm going to buy one of those trouble shooting pressure gauge so i can read the pressure inside the pipes as well.

but from what you said sounds like it is normal. thanks for your input!!!

[KenB925]

What you need is a solid cap to replace that pesky pressure relief valve. An added benefit is better water pressure!
DO NOT DO THIS IT COULD KILL YOU

[DETRoadster]

OP hasn't returned or commented since his original post. Something tells me he didnt heed our advice and was busy installing a 4th pressure relief valve when tragedy struck.