30psi relief valve leaking

[Moose]

I'm trying to take a trip with my family and need to run my oil boiler for a week or two while I'm gone. I fired it up and every thing worked fine, except when the boiler would reach 170F - 190F the 30psi relief valve would start dripping and then pouring water. I replaced the valve, fired it back up still leaking. I checked the expansion tank which seemed to be water logged and replaced it. I fired it back up still leaking. I replaced the water feed reduction valve to one that was factory set to 12- 15 psi. still leaking. I'm kind of at a loss. I've been racking my brain trying to figure what else could cause the pressure trip the valve. I don't trust the pressure gauge on the boiler it is reads only 12psi, but I'm not sure if I've ever seen it move. Any Idea's???? Great Grand parents, Grand parents and Grand children are anxiously waiting for me to find a fix.

 

[leaddog]

You need to check the pressure in the expansion tank. I'm not sure but think the air pressure in the tank with it off should be set at about 15psi. That gives it room to exspand. If it is set to high it won't work as there will be to much pressure build up as the water expands and if to low it will fill up and there won't be any more space to expand. Also get a new guage so you can see what the press is doing and that will help you find out what is going on. My guess is the tank press wasn't set right.
leaddog

 

[Moose]

Thanks for the response I'll give that a try. I've been looking for a new pressure gauge, with no luck locally. Guess I'll have to search the web.

 

[Moose]

Should I take the expansion tank off the take a pressure reading or can it stay on the system?

 

[taxidermist]

You want it in the system.

 

[leaddog]

The expansion tank has to have the press reading taken with no pressure in the water end. if you take the reading with water in it you will get the pressure reading of the system. You want the reading with out water as that give you how much air pressure you have in the tank. Then when you put it on the system and the water heats up it will compress the air and give you expansion room.
leaddog

 

[Eric Johnson]

The pressure in air side of the tank, when removed from the system, should be 12 psi. If you remove the tank, be sure to isolate it, and be prepared to get a face full of water when you unscrew it. Best to wrap a towel of some other barrier around the connection. The pressure behind the bladder will force the water in the other side of the tank out at whatever the system pressure is.

 

[Moose]

I couldn't find my good pressure gauge, and had to resort to a cheap tire gauge. I took the reading with the tank on the system and running. It read around 12psi, and the PRV was leaking. I let a good amount of air out of the expansion tank to give it some cushion and the leaking stopped until the next heat cycle then started again. I guess I'm going to run out and see if I can locate a new gauge for the boiler and a more accurate one to check the expansion tank. I'll take the tank off , drain it and charge or discharge it to 12 - 15psi

 

[Eric Johnson]

Yeah, letting air out of the bladder while it's attached to the system only provides temporary relief, then it comes back even worse. Disconnect the tank and recharge it to 12 psi and you should be good to go, if the tank is indeed the problem. Funny you can't find a pressure gauge. I think I've seen them at Home Depot for around $5. Any plumbing/heating supply place should have one, too. You can check your existing gauge by lifting the lever on the domestic water feed valve to bypass the regulator. That wont' tell you if it's accurate, but it will make it move up as the system pressure increases. Then let some water out of the system to get it back down.

 

[Moose]

If you remove the tank, be sure to isolate it, and be prepared to get a face full of water when you unscrew it. Best to wrap a towel of some other barrier around the connection. The pressure behind the bladder will force the water in the other side of the tank out at whatever the system pressure is.

unfortunately I cannot isolate the tank. What I had to do last time is shut the boiler down, shut the water supply off and bleed some of the pressure off. i then quickly removed the tank and plugged the opening to keep the pressure from gravity from draining the system any more than needed.

 

[taxidermist]

You want it in the system.

Sorry I was told to leave it in the system and just close the ball valves to get my reading.......... I will be out checking mine when the fire goes out.

 

[Eric Johnson]

Do you have a hot water coil in your boiler? If so, it may be leaking, causing your system pressure to exceed 30 psi. Of course, that would happen at any temp, not just at normal operating temp. If you suspect the feedwater valve, isolate it (or shut off the water pressure to your house) and see what happens.

 

[Moose]

I just returned from the store. I found a plumbing supply that I've driven past a million times and never noticed before. Got a new gauge installed along with two new auto air valves. I removed the pressure tank and charged it to 12 psi. I don't believe I have any coils. As far as I know its just a tank and burner. The guy at the plumbing store said that my filter on my pressure regulator was clogged.. I find it hard to believe since I just put it on yesterday, and I was fortunate enough to buy one at lowes that does not have a cleaning access. I only want to do one thing at a time anyways so that I know for sure what the problem is for future ref...

 

[Moose]

You want it in the system.

Sorry I was told to leave it in the system and just close the ball valves to get my reading.......... I will be out checking mine when the fire goes out.

No worries. we all get to learn a little something here. More fun that way.

 

[Moose]

Well I put 15 psi in the expansion tank and put it back on the system. As soon as I turned the supply back on I started leaking water out of the PRV The new pressure gauge read only 10 psi I'm kinda at a loss. I'm going to return the pressure regulating valve and try a new one. I'm not convinced that this will fix my problem but the plumber sure is so I try his remedy. I'm going to humor myself and put on another new 30psi PRV. If that dosn't work I guess I'm back to square one. At least the new auto air release valves work nice.....

 

[twofer]

When I got my system up and running I had the same problem as you. I ended up isolating the boiler and expansion tanks and then bleeding off the pressure. The pre-charge in my small expansion tank was 15psi and the large expansion tank was 27psi! Both tanks were promptly brought back down to 12psi and I haven't had a problem with the pressure relief valve since.

I realize this isn't going to help you but I figured I'd throw it in the thread in case someone is experiencing the same problem and finds this thread in a search.

 

[Eric Johnson]

Well I put 15 psi in the expansion tank and put it back on the system. As soon as I turned the supply back on I started leaking water out of the PRV The new pressure gauge read only 10 psi I'm kinda at a loss. I'm going to return the pressure regulating valve and try a new one. I'm not convinced that this will fix my problem but the plumber sure is so I try his remedy. I'm going to humor myself and put on another new 30psi PRV. If that dosn't work I guess I'm back to square one. At least the new auto air release valves work nice.....

No way that valve should leak if the system pressure is below 30 psi unless there's scale or other crap preventing it from closing completely. When you put on the new one and top off the system, vent it from somewhere other than the valve. That way you'll know you have a good seal. You might have really dirty water.

 

[Moose]

Well I got a new relief valve and it is installed. I haven't charged the system because as I was changing the pressure regulator I popped a shady soldering job right off the main. If I would have had soap with me i wouldn't have to shower tonight. needless to say I said a few choice words. After I shut the water off I saw the cause. Someone soldered a the half inch copper pipe into the main with a tee but only put the copper at most an eighth inch into the tee I couldn't believe it. I cant believe it lasted this long. Anyways I'll let you know the out come when I get the water back on.

 

[Moose]

After everything is all said and done, i had a faulty PRV. When my grandfather was alive he used to tell me just because its new doesn't mean it works. Guess he was right again. the system is now dry and working properly pressure reads around 18psi, and the wood burners will get a break for about a week. Thanks for everyone's help.

 

[Eric Johnson]

I know the feeling well--going on vacation in the winter and suddenly the heating system doesn't want to cooperate. Of course, I used to wait until the last minute to switch over to the oil (being cheap and all), and it makes for some tense moments. Then you sweat out your time away, hoping everything stays running.

But it sounds like you've got things under control, Moose. Maybe learned a few things in the process. I know I always did. Enjoy your time away!