Varying boiler pressure and plumber replacing relief valve

mark schofield

I had an expansion tank (diaphragm type) that was waterlogged and had the high pressure swings when the boiler went from 130 to 180. Water came out of the charging valve when I depressed the valve insert so I figured it was a leaking diaphragm. Took the expansion tank off, tried to charge it, and air came out of the water side. With a new tank installed, the pressuer rise is now 12 psi at 130 deg to 18 psi at 180 deg. and no more dripping relief valve.

Nick_27

varying boiler pressure and plumber replaced the relief valve

Hi there: I have an older boiler (~20-30yo) in a house we just bought. The problem is that the pressure varies widely when the boiler turns on. It goes from 12 psi up to 30 psi and then the relief valve goes off.

I had a plumber in here to look at it (I thought it might need a larger expansion tank) and he basically replaced the relief valve (which was 30 psi) with one that is 125psi! Isn't that too high? (He said it was leaking, but it wasn't before he got in there.) He also put the pressure in the system up to 15 psi and put more air in the expansion tank (he said it was slightly under inflated). Doesn't seem worth the $380 bill.

In the system, from the cold water supply I have a pressure reducing valve (set at ~12 psi) then a relief valve (30 psi)(B&G) before the boiler, but also on top of the boiler (where I used to have another 30 psi relief valve) I now have a 125 psi relief valve.

Does this make sense to anyone? Shouldn't I just get a larger expansion tank to even the pressures out? And isn't 125 psi hazardous?

Thanks,

Nick.

Ted_9

Well.

First off, do you have two pressure reliefs? Do you have a tank less coil for your domestic hot water? Is the 125 relief for the domestic hot water side?

Also, you may need a larger expansion tank and the proper cold fill. What floor of the house is the highest heat emitter?

Al Letellier_9

expansion

first of all, get that 125# relief out of there....is that plumber crazy or what??? He should stick to running pipe !!!
IF you have a second 30# relief and it isn't leaking, it is either bad, or its OK and the other one was bad and should have been replaced with a like valve. As to the expansion tank, the only way to properly check and charge a tank is to isolate it from the system and relieve all the pressure on the system side, then check and recharge if needed. If he didn't do that, your tank may now be overcharged. The simple fact that he installed a safety rated way to high for your boiler leaves little faith that he did the rest of it correctly. Get a pro over there to make things right and I would attempt to get reimbursed from the first guys. If he won't, report him to your local inspector or code authority. Guys like him are dangerous and give the industry a bad name. ( I'm assuming the info you gave is correct...have a pro check it out)

Nick_27

Yep, two pressure reliefs. No the 125 is not for domestic.

The boiler system is completely separate from the domestic hot water system with a gas hot water heater. (I would understand a higher psi relief valve on that system.)

And yes, for the water fill there is the on/off valve, and in sequence a B&G 12 psi pressure reducer and a 30 psi pressure relief valve. Then on top of the boiler is another pressure relief valve that used to be 30 psi and was replaced with a 125 psi valve.

The boiler is in the basement and only heats the first floor of the house with one radiator in the basement.

ALH_4

Relief

As stated before, it sure sounds like an expansion tank issue to me. You need a 30psi relief on the heating system. 125 is far too high.

I guess the plumber you had look at your system figures "who needs expansion tanks when you can just vary the pressure from 10psi to 125 psi?". I bet that 125psi valve doesnt leak.

If the pressure varies from 12 to 30 and back to 12 when cold, then it really sounds like an expansion tank issue to me. If the pressure hits 30, blows the relief valve and then stays at 30, then the fill valve may be the culprit. I am not a fan of leaving them on after filling the system and purging the air. It is best to close the shutoff on the makeup water after purging.

Nick_27

The one thing I think they did was test the tank.

Yeah, I had thought of that too, and had checked the valve on the bottom of the expansion tank, but no water came out. I then checked the pressure and it was 15 psi, but I hadn't separated it from the system.