Author Topic: TPR valve dripping after testing it (Read 13713 times)

psu256

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TPR valve dripping after testing it
« on: June 26, 2013, 10:18:42 AM »
Well, me being a relatively new homeowner, discovered the past weekend that I have been neglecting to test the pressure relief valve on my hot water heater. Now that I have done so, I am getting a slow drip out of the drain pipe. I tried turning down the temperature on the tank last night (which I wanted to do for electric costs anyways) but it looked like I was still getting some dripping this morning. It isn't much, nothing a daily paper towel couldn't take care of, but it is annoying me.

Any ideas on how to get it to stop?


Spork

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Re: TPR valve dripping after testing it
« Reply #1 on: June 26, 2013, 11:12:41 AM »
Is it possible some sediment or corrosion flake got stuck in the valve? Draining the tank until clear*, then testing it again might help. (Of course, if that's not what happened... it might just make it more angry.)

*I've had good/bad success with draining water heaters. Some of the drains are cheaply made and have basically "never been opened". If you have a cheap plastic hose bib drain, I might just leave it alone. Otherwise, you might find a second leaky spot when you're done.
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psu256

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Re: TPR valve dripping after testing it
« Reply #2 on: June 26, 2013, 11:47:50 AM »
I'm guessing that dirt is likely the problem. The water was defintely gritty coming out of the pressure relief piping when I tested it (easy to see in a white bucket!). I know the heater was installed in 2008, and the previous owner was a 60-something widow so I'm guessing she was not big on the house maintanance.

(I'm happy to do maintanance but I've never lived in a house before two years ago - always apartments. So I know just about nothing lol)

notquitefrugal

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Re: TPR valve dripping after testing it
« Reply #3 on: June 26, 2013, 02:16:44 PM »
Disconnect the power and flush out the water heater. If it has a plastic drain valve, now would be a good time to replace it with a metal one--the plastic ones tend to become brittle and break. Check the anode rod if you can. When you fill the tank back up, activate the TPR valve a few times to try to remove any sediment which may be clogging it. If it still drips, replace it. Don't turn the power back on until the tank is completely filled with water, as that will burn out one of your heating elements, and then you won't have hot water.

I try to repeat the drain/flush process every six months or so.

psu256

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Re: TPR valve dripping after testing it
« Reply #4 on: June 26, 2013, 02:44:25 PM »
Check the anode rod if you can.

What am I looking for if I check the anode rod?

Spork

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Re: TPR valve dripping after testing it
« Reply #5 on: June 26, 2013, 02:47:16 PM »
http://aricoplumbing.com/waterheater/images/anode-rod-compare.jpg

There is a random google of a good and a bad sacrificial rod.
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Greg

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Re: TPR valve dripping after testing it
« Reply #6 on: June 26, 2013, 06:55:19 PM »
The PRV should be piped to the outdoors, is yours? As others have said, debris between the seal and the seat.

psu256

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Re: TPR valve dripping after testing it
« Reply #7 on: June 26, 2013, 08:27:34 PM »
The PRV should be piped to the outdoors, is yours? As others have said, debris between the seal and the seat.

No, mine isn't piped outdoors - it just drips out on my floor. Good times.

I turned the temperature down last night and it seems to have gone 24 hours now with no dripping - hope it stays that way...

Welmoed

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Re: TPR valve dripping after testing it
« Reply #8 on: June 27, 2013, 06:28:32 AM »
The PRV should be piped to the outdoors, is yours? As others have said, debris between the seal and the seat.

In our area, the TPR pipe needs to terminate between 4-6" off the ground, and the pipe must not be threaded. You can terminate the pipe over a floor drain, but you can't make a sealed connection.
The whole point of a TPR valve is that it's a warning mechanism as well as a safety mechanism: if you see water coming out of it, you have a problem. It needs to terminate close to the floor because if the temp or pressure in the tank gets too high, extremely hot water is going to spew from that pipe and it WILL burn you almost instantly.
Water heaters should be set for a temperature of no more than 120 degrees F.
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DirtBoy

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Re: TPR valve dripping after testing it
« Reply #9 on: June 27, 2013, 09:29:17 AM »
My gas water heater is about 12 years old. About a year ago, when my TPR started leaking, I ended up draining the water heater and replacing my TPR. Been good so far. My recommendation is at least remove the valve and examine it and most likely replace it. My metal valve was very cheap to replace, $5 or so

keepingmobens

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Re: TPR valve dripping after testing it
« Reply #10 on: June 28, 2013, 04:53:20 PM »
This just happened to us, and it turned out the main pressure regulator to the house had failed and was letting the water in at full pressure, causing the TPR valve to leak. You can buy a pressure gauge at a hardware store for a few bucks to check the pressure at one of the hose bibs at the back of the house. It should be about 40-60psi. Ours was at 120 before we fixed the regulator.
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Nords

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Re: TPR valve dripping after testing it
« Reply #11 on: July 02, 2013, 11:27:29 PM »
Well, me being a relatively new homeowner, discovered the past weekend that I have been neglecting to test the pressure relief valve on my hot water heater. Now that I have done so, I am getting a slow drip out of the drain pipe. I tried turning down the temperature on the tank last night (which I wanted to do for electric costs anyways) but it looked like I was still getting some dripping this morning. It isn't much, nothing a daily paper towel couldn't take care of, but it is annoying me.

Any ideas on how to get it to stop?
Oooh, that touched a nerve. Let me weigh in with the experience of 20 years aboard U.S. Navy nuclear submarines: Stop testing your relief valve.

It looks so tempting, sitting there with its little warning label and the handy lever. Its presence is required by the boiler safety code, and every self-respecting plumber would recommend that you check it at least annually. Maybe semi-annually would be safer. Well, I guess quarterly would be even better, but monthly might be best of all. Of course you'll get a better routine going if you check it every day. But wait, what if it stopped working in the last 24 hours? How long have you been (as far as you know) unprotected from a temperature or pressure excursion?

And why stop with the manual check of the pressure spring? Maybe there should be a way to test the temperature actuator, too, right?

You see where this logic leads.

Submariners spend a lot of time doing maintenance at its required intervals, and they're inspected (and held accountable) on their proficiency at doing so. Part of the life is checking that relief valves lift within specification. At least 50% of the time, the relief valve would lift just fine, but it would fail to completely re-seat. (Required leak rate: "zero.") Hours of hilarity would ensue (usually along with weird plant-testing conditions and lots of extra watchstanders waiting until they could stand down) as the mechanics attempted to clean, tweak, and re-seat the valve. You quickly learned to have a spare relief valve ready to install before you ever started testing the installed relief.

When I actually needed a relief valve to lift, it never failed us. In fact a few times it lifted too soon, or too enthusiastically.

My heretical suggestion is that you never touch your relief valve again, or at least don't give in to the temptation until you have a spare one ready to install. It's highly unlikely that your water heater will ever experience a huge pressure excursion that opens the spring-actuated relief. If anything fails, it'd be the thermostat on the heater element (also highly unlikely) trying to turn the water heater into a steam generator. In that event, the thermally-actuated portion of the relief would handle the problem just fine. I also suspect that at least one faucet in the house would start leaking relieving pressure before the water heater relief stepped in.

Heck, I even hesitate to drain water out of the bottom of our heater to get rid of the sediment. We have a whole-house water conditioner and we regularly check the anode rod, so we hardly ever find any sediment anyway.

Anode rods can be a whole 'nother exercise in frustration, but I recommend checking those every 2-3 years:
http://familyhandyman.com/plumbing/water-heater/extend-the-life-of-your-water-heater-by-replacing-the-anode-rod/view-all

Start early in the morning (after everyone's enjoyed a hot shower) and make sure the hardware store is open late... just in case.

Note that the photo shows the guy pulling his rod straight up out of the water heater, because he clearly does not have eight-foot ceilings in his garage. It's worth the extra bucks to buy a segmented anode rod (bendable) so that you don't have a ceiling-clearance problem on the next check.

You'll also need a 1-1/16" socket (which typically requires a 3/8" drive), and probably a three-foot torque-assist pipe. It's also convenient to use Teflon tape when you install the new anode rod so that it's easier to loosen the next time.
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Nudel

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Re: TPR valve dripping after testing it
« Reply #12 on: July 24, 2013, 07:36:20 PM »
I'm in agreement with Nords. Makes sense to me and I wish I'd had that advice 6 months ago. I checked the valve after it being likely untouched for 12 or so years then by about a month later that little drip suddenly started cranking out water.

Thankfully a new valve was all that was needed. Not too expensive either.