Replacing Furnace Press relief valve (Help!)

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About a week to go before my house is closing and my pressure relief value went. I got a replacement value at Home Depot. I turned off the water supply that seems to come in to the furnace near the value. I started taking the old value off to replace it and I think the valve is under pressure still (I guess from the gas furnace itself) since once I almost all the way off water started coming out of the joint near the value. Can some one lead me through what else I have to shut off to replace the value? Thanks!
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snipped-for-privacy@gmail.com wrote:

If this is a hot water (Hydronic) system, you'll probably have to drain the entire system.
Good luck. I think you're biting off a lot.
Jim
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Jim, Thanks. It's gas hot water. I am probably in over my head. What do you think a reasonable price to pay someone to replace the value is? Thanks.
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snipped-for-privacy@gmail.com wrote:

Call around and ask. Prices vary all over the country.
Also.....it's possible the valve is opening because the pressure in the system really *is* too high. This can happen when the water feed valve sticks open.
Jim
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wrote:

That's not the only reason.....
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Retail on the valve plus $50 an hour for labor.
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Christopher A. Young
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wrote:

Jim, I also have a problem with my hotwater system. I went down to my basement and water was spewing out of the bottom of my pressure reducing valve. I notice that there seems to be a plug which is missing. Are these parts readily available or do I need to replace the whole unit.I am not sure of the model of the valve. Looks like 2 valves in tandem right after the water inlet.
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Mike wrote:

That's a dual control. First, a pressure reducing valve which is set to maintain a specific "height" of water in the system.
Second is a pressure relief valve which opens when system pressure exceeds (usually) 30 psi.
The relief valve has a discharge port and that may be where water is escaping (as it should).
Typical style: http://www.cashacme.com/genheating.html
See what the boiler pressure gauge reads. Normal is 12-15psi (depending on building height, of course). If way over that, the valve may be relieving for good reason. If normal range, the relief valve may be defective.
Jim
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Furnaces heat air, boilers heat water.
Do you have a separate heater for hot water or is it integrated into one unit? If the heater does both, there are two valves, one feeding the hot water, the other feeding the heater portion. Close that valve. There will be some internal pressure that has to be relieved. Put a bucket under the pressure relief and pull up the handle. That takes care of most. When the valve is removed, gravity will still allow some water to flow out.
Not seeing exactly what you have, you probably need some Teflon pipe tape for the threads, a pipe wrench and a large adjustable wrench to open the coupling. Undo the old, put in the new, snug, not overtightened. Slowly open the valve to let water in.
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The boiler and the hot water heater are separate gas powered units. I shut off the inlet value that's in front of the water feed pressure valve. I then put a bucket under the pressure relief valve and pulled up on the handle, about 1/2 gallon of water came out fast which leads me to believe the system is still under pressure, yes? That would imply that Jim is right that the whole system needs to be drained? Should I keep draining out the water till it slows, or should I just give up :-) Thanks guys for your help....
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Half gallon is not much. You have the potential to drain all the water sitting in pipes above the valve. If it was under pressure, it would be leaking out rather hard as soon as you cracked the valve or fitting open. Much like a faucet.
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Thanks Edwin. Since it's in the basement all the water is above this. Should I try draining some more? It is coming out like a faucet turned on about 75%. _stupid_ question...should I turn the furnace off? The pilot light should stay on, yes? If drain the water out could I damage anything? Thanks again.
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Close the feed to the boiler, then drain
No reason to turn the pilot light off. Thee will still be some water in the boiler so it will not be harmed in any way.
One you refill the system, there will be air in the lines. Someplace there will be a drain, probably in the return line, that you can open to remove the air.
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You should call a qualified service technician. Boilers can become dangerous if you don't know what your doing.
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He is working on a water valve, not a boiler. Service technician may not know any more about it that he does. If the OP is not qualified, a plumber would be a better option. I'd agree if he was fooling with ignition systems or flames and gas valves.
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Hi Edwin, hope you are having a nice day
On 29-May-05 At About 09:13:30, Edwin Pawlowski wrote to All Subject: Re: Replacing Furnace Press relief valve (Help!)
EP> >> You should call a qualified service technician. Boilers can become >> dangerous if you don't know what your doing.
EP> He is working on a water valve, not a boiler. Service technician may EP> not know any more about it that he does. If the OP is not EP> qualified, a plumber would be a better option. I'd agree if he was EP> fooling with ignition systems or flames and gas valves.
Yes Ed But remember that a boiler is running at usually 180 degrees and you just told him there is no reason to shut down the pilot which also means it could possibly come on. also what if he doesn't get all of the pressure out and pulls the valve and sprays hot water on himself?
-=> HvacTech2 <=-
.. "A friend of mine is in jail for counterfeiting pennies..."- s.w.
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True, I should have mentioned the simple step of turning the heater off at the switch. I know to do that, but not everyone would. This time of year most of us have no need for heat, but some places still get chilly.
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Hi snipped-for-privacy@gmail.com, hope you are having a nice day
On 28-May-05 At About 17:00:21, snipped-for-privacy@gmail.com wrote to All Subject: Re: Replacing Furnace Press relief valve (Help!)
t> From: snipped-for-privacy@gmail.com
t> Thanks Edwin. Since it's in the basement all the water is above t> this. Should I try draining some more? It is coming out like a t> faucet turned on about 75%. _stupid_ question...should I turn the t> furnace off? The pilot light should stay on, yes? If drain the t> water out could I damage anything? Thanks again.
You really should have it checked by a pro first. there may be a reason that water is coming from the relief valve and it may not be defective. also, if you drain the water it will also need to be bled after you are done and this can be tricky for someone who doesn't know how to bleed it properly.
-=> HvacTech2 <=-
.. "I bought instant water but I don't know what to add..."- s.w.
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You may have a waterlogged expansion tank or a diaphram tank with a ruptured diaphram. If that is the case, replacing the relief valve won't help. You may also have a bad water feeder. You may have a bad relief valve. Those are the most likely problems.
Stretch
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Beating a dead horse here. The gauge on the side of the furnace says 21 PSI with a temp of 100. SInce I have the water intake shut off and water isn't spewing out the pressure relief valve can I assume the pressure relief valve is OK?
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