Gas Hot Water heater won’t shut off

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Donski

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Hi all. Long time lurker here.
Saturday when installing a new dryer I had to turn the main gas valve off to replace the shutoff valve at the dryer. The next morning HW heater was off. I relit it and the pilot flame was yellow/orange but stable. The next day HW heater won’t turn off and today I found that water has been slowly escaping out of the pressure relief valve. HW heater is about 10 years old.
Is it just time to replace or is there a repair possible? Sounds like a thermostat issue. Is there an internal sensor or is it at the control valve.
Thanks
 

jadnashua

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The flame should not be yellow/orange! It sounds to me (I'm not a pro) that when you turned the gas back on, it dislodged some crud and the gas valve to the WH got partially blocked, which may be why it may have shut down. Somebody with more experience may have some other thoughts. The average life of a gas WH is about 7-years. Now, they could last decades, but that is fairly rare. Looked at that way, you're on borrowed time.

Sounds like the valve is sticking...keeping the burner lit. This can lead to bad things, worse than just dumping extremely hot water out of the T&P valve. That valve is designed to open when the water gets to 210-degrees, just below boiling, or if the pressure exceeds 150PSI...my guess is it's opening because the water is too hot by a long shot.

While you could replace the gas valve assembly, at 10-years, I'd be more inclined to replace the WH. If the T&P valve failed to open, it could literally launch the WH through the roof from the steam pressure. You need to fix this, and shut the WH off NOW while you decide your path.
 

Donski

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The flame should not be yellow/orange! It sounds to me (I'm not a pro) that when you turned the gas back on, it dislodged some crud and the gas valve to the WH got partially blocked, which may be why it may have shut down. Somebody with more experience may have some other thoughts. The average life of a gas WH is about 7-years. Now, they could last decades, but that is fairly rare. Looked at that way, you're on borrowed time.

Sounds like the valve is sticking...keeping the burner lit. This can lead to bad things, worse than just dumping extremely hot water out of the T&P valve. That valve is designed to open when the water gets to 210-degrees, just below boiling, or if the pressure exceeds 150PSI...my guess is it's opening because the water is too hot by a long shot.

While you could replace the gas valve assembly, at 10-years, I'd be more inclined to replace the WH. If the T&P valve failed to open, it could literally launch the WH through the roof from the steam pressure. You need to fix this, and shut the WH off NOW while you decide your path.
 

Donski

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Thanks. That’s what I was afraid of. I had read about the obstructed Pilot tube as a cause for the flame color. Looks like I’m in the market for a new HW heater. I shut it off last night and turned it on just long enough for a shower this morning. I’ll be babysitting it for a while until a new one is in place
 

John Gayewski

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Thanks. That’s what I was afraid of. I had read about the obstructed Pilot tube as a cause for the flame color. Looks like I’m in the market for a new HW heater. I shut it off last night and turned it on just long enough for a shower this morning. I’ll be babysitting it for a while until a new one is in place
Depending on your skill set changing the has valve assembly would be an option. Possibly disassembly and cleaning and reassembling would fix it.

There's no saying a gas valve would fix it though, in which case you're out the money and then still need a thermostat for it. But both of those would still be cheaper.

In any case be careful.
 

Donski

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Thanks for the replies. It occurs to me that the water isn’t getting very hot. Is it because the PRV is leaking or the thermostat is bad? Is there a way to test and isolate the problem? I guess I could install a new PRV and see if it does the same thing?
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jadnashua

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PRV=pressure relief valve...T&P= temperature and/or pressure relief safety valve...two different things.

If you T&P valve is now just leaking, and the water isn't hot, it's either open because the pressure is too high, or it is stuck open, and has failed.
 

Jeff H Young

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first off the pilot should stay on . if the main burner is staying on and not shutting off thats a problem , its odd that the water isnt very hot?
A mixed message there it seems.
 

Donski

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I want to thank the people who responded. It turns out the the Pressure relief valve was leaking and causing the burner to stay on and never reaching temperature. I didn’t notice it because it dumps out on the back of the house and since it’s been raining I didn’t notice.

A quick swap and everything is back to normal.
But I’m also starting to shop for a Tankless heater.
 
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