Water heater T&P valve

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tornitore45
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Location: USA Texas, Austin

Water heater T&P valve

Post by tornitore45 »

I had to change mine. I can understand how the pressure side of the valve works, is a simple spring loaded job.
I can not understand what is the function of that 4" long 3/8" diam stick of what looks like ceramic. It is pretty loose in its seat and can not see how it could be working on expansion.

Anybody knows? Google search tell why you need it and lots of obvious trivia but not how it works.
Mauro Gaetano
in Austin TX
hammermill
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Re: Water heater T&P valve

Post by hammermill »

As it expands the internal temp and pressure raises the flapper on the seat was what I always thought
dly31
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Re: Water heater T&P valve

Post by dly31 »

I am not sure but think there is a wax capsule and rod inside the long closed end tube. As the wax expands from heat the rod pushes out and opens the valve.
Don Young
hammermill
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Re: Water heater T&P valve

Post by hammermill »

I think you are right about the wax element. Lots of tempering or mixing valves are the same way
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tornitore45
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Re: Water heater T&P valve

Post by tornitore45 »

Thanks, that explains it.
Next question

Is the temp actuation a one shot deal, or it reset itself.

Just curiosity, I changed it and now has no leak when cold, as the old one.

Bad news when you have two faults, element and valve.
Mauro Gaetano
in Austin TX
hammermill
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Re: Water heater T&P valve

Post by hammermill »

I feel it depends on water when they fail they turn into leakers because of crud in the valve seat or corrosion.

if a stat sticks on the unit will cycle many time trying to protect you.
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steamin10
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Re: Water heater T&P valve

Post by steamin10 »

Safty issue rhyme : When in doubt, throw it out.
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wsippola
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Re: Water heater T&P valve

Post by wsippola »

Sounds like you've changed it anyways. But in general, these wax actuators are not one shot deals. Thermostats in engines use them, as do some temperature switches. I added wax to the switch on an 81 Goldwing to get it to work again - I suppose over time, some wax had oozed out.
plumberzpieco
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Re: Water heater T&P valve

Post by plumberzpieco »

The problem is once they open they do not close in the exact same spot. It is not a precise mechanism, just spring loaded. I get people asking me all the time if they should flip the lever to make sure it works. Sure go ahead then you'll have to pay me to replace it. Then they tell me the "home inspector" did it and said it was a good idea.
dly31
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Re: Water heater T&P valve

Post by dly31 »

Depending on how they are oriented, testing the valve can leave water around the spring and other parts which can rust/corrode them. I think they are reliable enough that testing is not a good idea.
Don Young
plumberzpieco
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Re: Water heater T&P valve

Post by plumberzpieco »

I must have jinxed myself by answering this thread, got a call yesterday "Hey that water heater you installed is leaking". I go check it out and sure enough the relief valve is dripping. So I tell the wife it's the relief vale. She say's "Oh you mean this thing with the lever". Interesting she know what it is and where it is. I inform her that it isn't a good idea to store the broom or mop next to it because they might bump the lever and cause it to leak. She say's "Do you mean your not supposed to touch that, cause I don't think I did. " I think I'm going to make stickers up with a warning DO NOT TOUCH THIS LEVER. Being a good repeat customer I promptly replaced it no charge.
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Harold_V
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Re: Water heater T&P valve

Post by Harold_V »

plumberzpieco wrote:I must have jinxed myself by answering this thread, got a call yesterday "Hey that water heater you installed is leaking".
I had a rather unusual experience (I think it was, anyway) years ago when I installed a water heater. Water pressure was rather high (well in excess of 100 psi), with no pressure reducer. The heater operated perfectly well for several months, but started dripping when it was up to heat. I installed a pressure reducer and the leak stopped permanently.

Harold
Wise people talk because they have something to say. Fools talk because they have to say something.
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