Water heater relief valve.

[Sid 03]

We have a water heater and it leaks water though the relief valve.
But, it only happens when the water heater is warm. If the temp is turned down (a.k.a. Off) the relief valve stops leaking.
What's causing that ?
Then someone volunteered that a few years ago a plumber was there and replaced the guts of that relief valve.
Leak: Its a little more than a constant trickle, does not appear to an issue with the expansion tank or water hammer effect.

Any idea what is causing this behavior ?
Thanks

[Ed Pawlowski]

Yes, heated water expands and increases pressure. You have two choices
to fix it. Replace the valve with a new one or repeal the laws of
physics.

[Bob F]

Or, fix the bad expansion tank.

Replacing the valve is trivial.

[Ed Pawlowski]

Yes, could be full of water

[gfre...@aol.com]

or add an expansion tank. They make small ones about the size of a
basket ball that can deal with the amount of expansion you get in a
water heater. If you aren't a plumber, you could get a "Y" adapter, a
3/4 NPT to hose adapter and hook it up where the washing machine
connects with a washing machine hose..

<https://www.homedepot.com/b/Plumbing-Water-Heaters-Water-Heater-Parts-Water-Heater-Expansion-Tanks/N-5yc1vZckr7>

[danny burstein]

Or bypass the "backflow preventor" valve between your home
and the municipal water supply and just let the exapanded
water, so to speak, push back into the water mains.

Oh wait. That's _VERY_ frowned on...



--
_____________________________________________________
Knowledge may be power, but communications is the key
dan...@panix.com
[to foil spammers, my address has been double rot-13 encoded]

[gfre...@aol.com]

This wasn't a problem before backflow preventers were a thing. . I
have a well so we have built in expansion protection in the well tank.
That is why people have expansion tanks on city water tho. Maybe the
house originally didn't have backflow protection and it was added
later, causing this problem.

[danny burstein]

In <ompnpg123a3ef5i39...@4ax.com> gfre...@aol.com writes:

[snip]

>>><https://www.homedepot.com/b/Plumbing-Water-Heaters-Water-Heater-Parts-Water-Heater-Expansion-Tanks/N-5yc1vZckr7>
>>
>>Or bypass the "backflow preventor" valve between your home
>>and the municipal water supply and just let the exapanded
>>water, so to speak, push back into the water mains.
>>
>>Oh wait. That's _VERY_ frowned on...

>This wasn't a problem before backflow preventers were a thing. . I
>have a well so we have built in expansion protection in the well tank.
>That is why people have expansion tanks on city water tho. Maybe the
>house originally didn't have backflow protection and it was added
>later, causing this problem.

That's actually my likeliest suggestion as to what happened.

And it was quite possibly added without the OP knowing..

[trader_4]

Assuming the system has one, most around here do not.

>
> Replacing the valve is trivial.

Could just be a bad valve. Should be trivial, unless it's an old tank
and it's rusted in, something bad happens when you try to get it out.

[Clare Snyder]

On Mon, 22 Nov 2021 10:49:02 -0500, Ed Pawlowski <e...@snet.xxx> wrote:

Not only that, but that valve is not ONLY a pressure valve - it has
a thermal component as well. Generally they are calibrated to release
at 210F or 150PSI (that is why they are called T&P relief valves)

[Clare Snyder]

On Mon, 22 Nov 2021 18:33:36 -0000 (UTC), danny burstein
<dan...@panix.com> wrote:

except when the house never had one. Never had one in any house I've
lived in or owned.

[gfre...@aol.com]

On Tue, 23 Nov 2021 17:23:50 -0500, Clare Snyder <cl...@snyder.on.ca>
wrote:

Me either except maybe the rental I lived in on Sanibel for a year. I
never had reason to look.

[Bob F]

True for me also.

[Bob F]

On 11/23/2021 2:22 PM, Clare Snyder wrote:
> On Mon, 22 Nov 2021 10:49:02 -0500, Ed Pawlowski <e...@snet.xxx> wrote:
>
>> On 11/22/2021 10:26 AM, Sid 03 wrote:
>>> We have a water heater and it leaks water though the relief valve.
>>> But, it only happens when the water heater is warm. If the temp is turned down (a.k.a. Off) the relief valve stops leaking.
>>> What's causing that ?
>>> Then someone volunteered that a few years ago a plumber was there and replaced the guts of that relief valve.
>>> Leak: Its a little more than a constant trickle, does not appear to an issue with the expansion tank or water hammer effect.
>>>
>>> Any idea what is causing this behavior ?
>>> Thanks
>>>
>>
>> Yes, heated water expands and increases pressure. You have two choices
>> to fix it. Replace the valve with a new one or repeal the laws of
>> physics.

Or, fix the expansion tank. That's almost as effective as repealing the

[Sid 03]

Home is 15 years old, so Yes it has an expansion tank and a chk valve to city water. (house has sprinkler system) The expansion tank has been replaced, but the relief on the hot-water-tank still leaks when the heat is turned up on the tank (natural gas).

Looks like replacing the valve will require removing the whole valve assembly. Is there any way to just replace the guts of it ? (spring + washer) Can you buy a kit for that ?
If I stick a pipe-wrench on that valve and something else breaks, I could end up replacing the whole tank ?! Right ?

[Bob F]

When I've done it, I just turn off the water and heater, drain the tank
to below the valve level, remove any outlet down tube from the valve,
then unscrew the valve with a wrench. Put tape or pipe dope on the new
valve, and screw it in and tighten with a wrench. It is not a big deal.
The valves are generally brass, so they do not tend to rust in place.

[gfre...@aol.com]

On Wed, 24 Nov 2021 09:40:03 -0800 (PST), Sid 03 <sidw...@gmail.com>
wrote:

Yup, the joys of home ownership. Bob is right, they are usually a non
issue to replace. While you have the water pressure drained down it
might be worth checking the precharge pressure on the expansion tank.
If this is not a bladder tank, just an inverted cylinder, simply
draining the system (open a faucet up high and down low) and letting
air back in might fix it, like "recharging" your water hammer
arrestors.

[trader_4]

Replacing the whole thing is the surest way, I wouldn't screw around trying
to replace parts, even if they were available. It should come out without
creating any new problems. There is always some small chance, but you
have to do what you have to do and even if it winds up screwed up, if that
tank is 15 years old, it's at or past it's typical life already. If you want to be
paranoid, you could have contingency plans for where to get a replacement
tank, etc just in case. Last one I did I bought it at HD and used one of their
rental trucks to get it home.