Leaking T&P valve


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Old 04-18-05, 08:22 PM
xqqz_me
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Leaking T&P valve

Hello... I have recently changed the pump and motor on my homes hot water heating system. The new pump and motor work great, but now I get a steady dripping out of my T&P valve. I replaced the old valve with a new one, but I still get the drip. From what I read in this site, it may be my expansion tank needs replaced or recharged, but I am not sure. I do have a pressure reducer in the fill line to the expansion tank. Any advice on how to trouble shoot this problem would be great.
 
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Old 04-19-05, 02:10 PM
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T&P valve

If you replaced the valve with a T&P (temperature & pressure) relief valve it was a mistake. Boiler relief valves are pressure only & usually set at 30 psig.
Make sure the proper valve is installed. If it is, drop the pressure on the system to zero & check the pressure in the tank by using a tire gauge. Normal tank pressure is 12 psig. If you get water out of the schrader (tire) valve, the tank is shot & needs to be replaced. The best way to check the tank is with it removed from the system. By removing it you can verify if the bladder will hold pressure.
 
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Old 04-20-05, 04:01 AM
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Grady... Thanks for the reply. I have installed the correct valve, but I have been calling it the wrong name. It is rated at 30 psi just like you said. Could you please tell me the best way to get my heating systems pressure down to zero so I can test my expansion tank? Thanks in advance.
 
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Old 04-20-05, 09:58 AM
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HI there,Shut the power switch to the boiler. Then, if you shut off the water supply to the boiler and drain out some of the water from the spigot at the bottom of the boiler, your pressure will drop to zero. I do not believe you have to empty it all. Just some. Grady or Ken will give you expert advice also, but this is the way I have always done it. A short piece of hose and bucket make it neater when you drain some out. Also, I have just lifted the lever on the pressure relief valve (your new one) and placed a bucket underneath the downspout and let some water out that way. Hope this helps.
 
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Old 04-20-05, 02:06 PM
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Originally Posted by xqqz_me
Grady... Thanks for the reply. I have installed the correct valve, but I have been calling it the wrong name. It is rated at 30 psi just like you said. Could you please tell me the best way to get my heating systems pressure down to zero so I can test my expansion tank? Thanks in advance.
As Bob said, you can either drain the pressure via the hose connection near the bottom of the boiler or thru the relief valve. In either case you will want to shut off the power & feed water first. Once the pressure is down, you can prop open the relief valve instead of removing the tank if you wish. If the pressure on the tank is low you can try to pump it up with a bicycle pump, air tank, or small compressor. If the pressure in the tank won't come up, it needs to be replaced.
 
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Old 04-20-05, 02:33 PM
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Thanks Bob and Grady, I will do like you said. I'll let you know how it comes out.
 
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Old 04-23-05, 03:41 AM
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I tested the pressure in my expansion tank (Extrol model 30) with the safety valve propped open and the feed water turned off. I got a reading of 5 psi. I pumped it up to 12 psi like it says on the body of the tank. I turned the power back on, and opened the feed line, then turned on the boiler. The safety valve seems to be leaking worse now. I did notice a few tiny droplets of water the first time I pressure tested the tank, but I think it must still be good, because it did pump up to the 12 psi. Could the tank be bad anyway? Thanks in advance.
 
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Old 04-23-05, 04:22 AM
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water droplets

If the droplets came out of the schrader valve, it is a good indication of a bad tank.
Is there a pressure gauge on the boiler & if so what is it reading?
Another way to test is, once the boiler is up to temp, check the pressure on the tank with a tire gauge.
If the pressure is 12-15 psig the relief valve would seem to be at fault.
If pressure is high, turn off the feed water & keep a check on the pressure. The reducing valve (feed valve) could be leaking thru.
 
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Old 04-23-05, 04:32 AM
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I didnt see here where you say what the boiler psi is when the pressure relief valve drips. Have you tried the like snap it on and off?????

ED
 
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Old 04-23-05, 09:13 AM
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The boiler psi is now a little over 10psi and the safety valve continues to drip. I did make sure it snapped shut tightly. I have never had a pressure reading over 30 psi on the boiler gauge, and still the valve is dripping. Could it possibly be that this brand new safety valve is bad? Maybe I damaged it installing it somehow, I am not sure.

I bought a new expansion tank today, because they are pretty cheap and it may not be a bad idea to replace this one anyway as it is fairly old. I guess if that doesn't fix it, I will have to look at the pressure reducer next. That is going to be a whole lot harder for me to replace, as I am not too good at sweating copper pipe yet. This is a good way to learn though. Any further input will be greatly appreciated, and thanks for the help so far.
 
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Old 04-23-05, 09:48 AM
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I cant see how a 30lb P/R valve can leak at 10 lb psi in the boiler. Can your psi temp gage be bad ?????????on the boiler????

ED
 
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Old 04-23-05, 04:42 PM
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Ed, it doesn't make any sense to me either, that's why I thought I'd throw this question out to you guys here who have way more experience than I do in these matters. The pressure gauge on the boiler could be wrong, but I didn't think it was because the psi readings I got at the pressure tank were pretty close to what it said on the boiler. Later on tonight, I will install the new Extrol tank, and see what happens. I reall wish I had a pressure gauge I could hook up to the feed line so I could test the water pressure there. That would tell me if my reducer valve was going bad or not.
 
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Old 04-24-05, 06:08 AM
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Today I installed my new expansion tank. While I had the old tank off, I was able to pressure test the fill line with a gauge I borrowed from the hardware store. When I turned the line on, I got a reading of 15 psi. I pumped up my new expansion tank to 15 psi also. I then turned everything back on and started the boiler. The gauge on the boiler climbed to about 18 - 19 psi and stayed there.

The safety valve is still dripping. I noted that when I changed the expansion tank, and the system pressure was zero, the valve STILL leaked. It is not water just left over in the discharge tube, but a constant drip, drip, drip. When I had the expansion tank off, I didn't get any dripping out of the feed line with the feed taps off, so I am at a loss as to why this is happening.

What I am going to do tomorrow is replace the valve again. It seem highly improbable, but I may have gotten a bad valve. Also, I may have tweeked it in the install without knowing it, or maybe there is some debris blocking the full seating of the seal.

thanks for the help.
 
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Old 04-24-05, 06:34 AM
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Hi xqqz, I have experienced valve seals not seating correctly because an excess piece of telflon tape had broken off during the tightening process. I know you have lifted the fast discharge flipper on the valve and let it snap back a couple of times, but the tape thought just came to my mind.
 
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Old 04-24-05, 08:42 AM
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Thumbs down Teflon Tape

This is exactly why I don't like teflon tape. Blasted stuff causes more problems than it's worth. Use a good pipe dope. Even one which contains teflon is ok.
It is entirely possible you got a bad valve or some debris is hung up under the seat. If opening it manually a couple of times doesn't cure the problem, replace it. The constant influx of fresh water will do major damage to the boiler.
 
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Old 04-25-05, 07:35 AM
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Victory

Today, I took off the old "new" safety relief valve. Just for the heck of it, I tried to blow a big puff of air through it to see what happens, and sure enough, I could hear and feel it leaking. So, I went down to the plumbing supply store and got a new one. After a few mishaps installing it, (this time I put a union in the discharge pipe so I wont have to cut it again....) I fired it up and brought it to full working heat. I did not see any leaks, but I put 2 bone dry buckets under the valve and discharge pipe that I can check later just to be sure.

I have the water temperature set at 180 degrees, and the pressure seems to run just over 20 psi. Is this ok?

Thanks for all the help with this.
 
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Old 04-25-05, 07:41 AM
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I have the water temperature set at 180 degrees, and the pressure seems to run just over 20 psi. Is this ok?
Temp 160 on and 180 off

One floor home 12 to 15 psi

two story home about 18psi

Psi is just what it takes to get water out of the top bleeder.

ED
 
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Old 04-25-05, 01:17 PM
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Unions

Glad you got it fixed. Unless I can swing the discharge pipe all the way around so it unscrews from the relief valve, it gets a union. This simple addition can turn a 30 minute job into a 5 minute job.
I wouldn't worry about the 20 psig. It's a little high but not worth getting worked up over. If the boiler was cold when you changed the valve, just drain enough water to drop the pressure to 12-15 & it will likely stay there.
 
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Old 04-26-05, 02:57 AM
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Grady, Bob, Ed, and anyone else who replied, I thank you. Winter comes pretty early here in Montana, and often stays kinda late. I am glad I wont have to worry about this working now, just in case we get another period of cooler weather. How much is piece of mind worth?

Thanks again.
 
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Old 04-26-05, 03:34 AM
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you're quite welcome
 
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Old 04-26-05, 01:28 PM
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xqqz_me

Originally Posted by xqqz_me
Grady, Bob, Ed, and anyone else who replied, I thank you. Winter comes pretty early here in Montana, and often stays kinda late. I am glad I wont have to worry about this working now, just in case we get another period of cooler weather. How much is piece of mind worth?

Thanks again.

That's why we are here. It really helps when we have a poster, such as yourself, who can follow directions. If you run into any other HVAC problems, we are here. There are dozens on other boards here with people just like us who will be glad to help with just about anything.
Stay Warm,
Grady
 
 

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