Give ne back my hat!

Water heater temperature-pressure valve is venting

So the house I bought has a 14ish year old water heater.

I went away for about 2 1/2 weeks so I turned off the power to the water heater.

When I returned and powered it back on, the temperature-pressure relief valve started discharging water.  A lot at first, but it has since slowed to a trickle.  The only problem is it won't stop.

Some Googling says this valve is a safety mechanism to prevent the water heater from becoming too hot or too pressurized.

My assumption at first was that since the water heater was cold for so long, warming the water inside all at once is causing it to expand and vent and thusly overflow the valve.  But it's been many many hours and this hasn't completely vented yet.  I've even run the hot water on all of the faucets for a bit.  That helps stop the venting, but after awhile it starts back up again.

The water pressure doesn't seem all that high.  If anything it's slightly lower than usual.  It also doesn't feel hot.  If anything it's slightly less warm than usual.

So, I don't think it's triggering because it's serving its intended purpose.

Did... the valve just break?  From the water heater being off for 2 1/2 weeks?
Permalink Wabi-sabi 
September 12th, 2017 12:53pm
I already ordered a replacement water heater so this is more a curiosity than anything.  I can live without hot water in the meantime.
Permalink Wabi-sabi 
September 12th, 2017 12:54pm
What was the discharge like the last time you flushed the water heater?

If the answer is that you didn't do that, are you aware that all water heaters require annual flushing, similar to how all clothes dryers require regular lint removal?
Permalink Reality Check 
September 12th, 2017 1:03pm
I was not aware.

I also have only owned this house for five months.
Permalink Wabi-sabi 
September 12th, 2017 1:27pm
Eh, 14 years is long enough for a water heater.

Probably, it's just the seal on the pressure valve has hardened and maybe cracked.  Or the valve is just sticking open a little.

Pull hard on that puppy and then let go -- it might re-seat itself.

But even if it does, at 14 years old, the bottom will rust out in a year or two.  Might as well get a new one, they're not that expensive.
Permalink SaveTheHubble 
September 12th, 2017 1:31pm
I already said I ordered a replacement.

Try to keep up.
Permalink Wabi-sabi 
September 12th, 2017 1:32pm
I was agreeing with your decision.

Try not to be so defensive.

</Defensive>
Permalink SaveTheHubble 
September 12th, 2017 1:35pm
I just replaced the water heater in the 17 year old rental property - it had started dribbling water out the bottom.  So 14 years is about how long I'd expect one to last.

Getting the tenant to understand that they would have to be there to let the plumber in was a challenge.  They didn't know how to program the garage door opener for a single-use code (despite me sending them a youtube video of how to do it). They didn't want to pull the emergency cord on the door. And somehow thought the plumber would magically have a key.  Ended up paying the property management firm an extra $300 to end the pain.
Permalink Send private email xampl9 
September 12th, 2017 2:36pm
If they're like the security valves in France, once they start leaking they often won't seal properly again once they're a bit old, like StH says.  I had to replace a couple lsat year.

I had a €100 higher water bill and it was because a non-obvious one of these bu99ers had been leaking for months (directly into a drain).
Permalink Trog 
September 12th, 2017 2:41pm
Is a water heater what is known as a geyser in actual english?
Permalink Bluebeard 
September 12th, 2017 4:06pm
You are probably right that the expansion of the water opened the valve. 

Once the old valve was opened, it wouldn't seal.  Thus the constant leaking.

Those valves can be replaced, but you did the right thing to replace the whole water heater being that it is so old.  Water heaters aren't very expensive.

Are you going to do the labor?  It isn't too hard if your house has copper pipes.  You might need to do some sweat joints to put in flex hoses, but it is pretty easy.
Permalink Legion 
September 12th, 2017 4:27pm
Why you really want the temperature + pressure safety valve to work properly.

https://www.youtube.com/watch?v=9bU-I2ZiML0&t=111s
Permalink Send private email xampl9 
September 12th, 2017 4:36pm
14 years is super old and Idiot has a point; it's probably never been flushed. Any number of things could be broken by this time. Good call replacing it.

You could turn on hot water faucets around the house and let it run to see if there's any air trapped in the lines and maybe it would stop leaking.
Permalink MS 
September 12th, 2017 5:36pm
> Are you going to do the labor?  It isn't too hard if your house has copper pipes.  You might need to do some sweat joints to put in flex hoses, but it is pretty easy.

Normally I'd be all about it, but the previous owner was a contractor and lived here forever, so naturally there's this Rube Goldberg machine style hosing around the water heater regarding some kind of radiant floor heating setup.  They also allegedly installed a whole house water filtration system that I haven't been able to locate.

I've also never plumbed anything before.

So... I'm just going to hire an expert this time for the install and have them teach me as much as possible about the setup in here.
Permalink Wabi-sabi 
September 12th, 2017 11:34pm
Be prepared for the possibility that the professional you hire will know less than you do and will make a make-do hack job of everything, while charging a fortune.

Hopefully you'll get lucky. Every place I've lived the first dozen or so plumbers, car mechanics, electricians, and heating/AC guys, despite being licensed, just took whatever hacky shortcuts and half assed solutions they felt like.
Permalink Reality Check 
September 13th, 2017 5:21am
You're crazy.
Permalink Wabi-sabi 
September 13th, 2017 5:35pm
Aren't we all.
Permalink , Cup 
September 13th, 2017 5:55pm

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