Pressure relief valve replacement

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Old 02-27-20, 08:42 AM
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Pressure relief valve replacement

Hi. My pressure relief valve has developed a small drip, since I opened it a while back. It's very slow, maybe fills a coffee can every few weeks. Pressure is at about 17 psi.
What's involved in replacing it? Seems simple, just want to make sure. thanks
 
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Old 02-27-20, 09:01 AM
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Use this video. It's as good as anything we can explain.

https://www.google.com/search?channe...kytMPjfy6uA452
 
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Old 02-27-20, 11:36 AM
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With all due respect to Norm that video is for a HWT T&P valve which operates basically the same but to change one on a boiler is a little more involved.

You must take the pressure off the boiler by draining it below the relief valve. How involved it gets depends on what you have for isolation valves. You may have to drain the whole system in which case it will have to be bled or if you have well placed valves in the supply and return lines you may be able to isolate the boiler and hardly lose any water.

Pics of your system would help if possible to see exactly what you have. Just in case you saw that video the relief valves are not the same either. The HWT has a temp & pressure relief valve and the one for your boiler is just pressure and it is a 30 psi relief valve.

Hope this helps a little.
 
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Old 02-27-20, 12:34 PM
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Did not know we were talking a boiler set up. Sorry.
 
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Old 02-27-20, 03:32 PM
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There are a few pics in my post from January titled "banging noise". Probably not enough though. I will take some more and post them.
 
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Old 02-28-20, 08:06 PM
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A common cause of leakage is rust partials on seat of valve. Try flushing them off with repeated activation of valve.

Because depressurizing system is a hassle make life easier for the future. Add a “ NPT shut off valve to expansion tank. To depressurize shut off valve, drain small amount of water until pressure drops to zero.

Also on either side of regulator/ relief valve install unions to make removal for service easier
 

Last edited by Grady; 02-28-20 at 11:24 PM. Reason: Dangerous advice
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Old 02-29-20, 12:29 PM
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Maybe i will try flushing it again and see if that helps. It didn't drip at all until i did that.
 
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Old 02-29-20, 02:54 PM
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Mine developes a leak every 2 or 3 years for no real reason. Last time I put a shut off before the valve so I can just close the valve and change it , easily peasy. I take the handle off the valve so it will not be closed accidentally. This also gives me greater confidence to "exercise" the valve knowing I can change it quickly and easily if it leaks after.
 
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Old 02-29-20, 03:47 PM
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I've had mine leak and with a little 'exercise' it stopped.
 
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Old 02-29-20, 06:11 PM
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Installing a shut-off valve ahead of the safety relief valve is an absolute no-no. Any codes would prevent that.
 
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Old 03-01-20, 04:46 AM
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Gilmorie is 100% correct. Should you forget to open that valve or the valve is not a full port valve you are creating a potential bomb. If you've ever seen pictures of a boiler explosion, it isn't pretty. Residents of the house often don't survive.
PLEASE DON'T INSTALL A VALVE BETWEEN THE BOILER & RELIEF VALVE.
 
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Old 03-01-20, 08:05 AM
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In post # 6 should have written “ Add a “ NPT ball valve with handle that shows On-Off position to expansion tank." Sorry about that.

Good design practice is to provide means to isolate for when there is service issue.

Fortunately on DIY.com readers have option to decide which approach to use.

Hope frankjc's leak has stopped. This source of No-No's tried to help. I try to provide solutions rather than find fault.
 

Last edited by doughess; 03-01-20 at 08:28 AM.
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Old 03-09-20, 06:26 AM
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I tried openeing and closing it a bunch. Can't get it to stop, I will replace it soon.
Thank you.
 
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