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Joe
Water Heater Temp/pressure valve leak

I have a gas fired stand alone water heater that leaks when water is being heated. I checked my water pressure at the inlet to the house and it is fine and the temp is set at 140 degrees. I installed a new valve and I have the same problem.

Do I need an expansion tank or something like that?

NashuaTech
Re: Water Heater Temp/pressure valve leak

When you say it "leaks" I take it you mean it's leaking out of the throat of the new valve you just installed.

A water temp setting of 140 degrees is a shade high to set it & could scald someone taking a shower; try reducing down to 130 or so to see if there's any change.

Has the leak been of recent origin, or has it been leaking for some time???

First check the tags on the new & old valve to make sure you installed the correct valve.

Typical pressure relief valve setting is 150 lbs psi.

Typical temperature relief valve setting is 210 degrees.

These values should be stamped on the little tag on the old valve as well as the new valve.

In other words, the water temp the water heater is making can't exceed 210 degrees and the house water pressure can't exceed 150 psi.

Please post back with the brand name & model numbers of both valves, and the results you got for the house water pressure.

johnjh2o
Re: Water Heater Temp/pressure valve leak

You need a thermal expansion tank. When the water is heated it expands causing the T&P valve to open. The valve is doing it's job. 140 degrees is also to hot.

John

NashuaTech
Re: Water Heater Temp/pressure valve leak

Hot water heaters supplying a domestic hot water circuit ordinaily don't need a thermal expansion tank; any rise in pressure due to expansion is partially absorbed by the piping & small amount of air in the top of the HWH; the rest of the pressure is backed up thru the water main out into the street main.

The exception is when a check valve (anti-backflo valve) is installed at the water main--in such cases they are usually required by code.

Sometimes the water main pressure can vary quite a bit between daily peak usage & overnight off-peak; this can create problems with varying pressure spikes in off-peak periods.

MSSP
Re: Water Heater Temp/pressure valve leak

Just wondering what type of WATER HEATER has air in the top? This sytem needs a therm expansion tank. Period!

Dobbs
Re: Water Heater Temp/pressure valve leak
MSSP wrote:

Just wondering what type of WATER HEATER has air in the top? This sytem needs a therm expansion tank. Period!

Well, we still haven't heard from the OP as to why all of a sudden something's changed after all this time & the valve is leaking.

It's just sloppy troubleshooting procedure to shoot off your mouth & insist on additional components & expense when the system may or may not need them----how about throwing in a new boiler while we're at it???

I agree with Nashua.

johnjh2o
Re: Water Heater Temp/pressure valve leak
Dobbs wrote:

Well, we still haven't heard from the OP as to why all of a sudden something's changed after all this time & the valve is leaking.

It's just sloppy troubleshooting procedure to shoot off your mouth & insist on additional components & expense when the system may or may not need them----how about throwing in a new boiler while we're at it???

I agree with Nashua.

The reason may be that a back flow device or a PRV has recently been installed.
John

Pelton
Re: Water Heater Temp/pressure valve leak
johnjh2o wrote:

The reason may be that a back flow device or a PRV has recently been installed.
John

Until we hear from Gator we don't know WHAT is going on there.

Sounds like Gator is just playing games with us.

I go along with Dobbs, and recommend a new water heater AND a new boiler, AND a new expansion tank.

I'd also replace the cold water piping back to the street shutoff.

JLMCDANIEL
Re: Water Heater Temp/pressure valve leak

I'm closing in on seventy years of age, have lived in several homes, and gone through I don't know how many water heaters but have never had to install an expansion tank. I have also never seen NashuaTech give false or misleading advice.

Jack

MSSP
Re: Water Heater Temp/pressure valve leak
Dobbs wrote:

Well, we still haven't heard from the OP as to why all of a sudden something's changed after all this time & the valve is leaking.

It's just sloppy troubleshooting procedure to shoot off your mouth & insist on additional components & expense when the system may or may not need them----how about throwing in a new boiler while we're at it???

I agree with Nashua.

Well there dobbs why do you say I am shooting off my mouth? I am going off the fact that he had this problem and then put in a new T&P and still has the problem.If this is a closed loop system with or with out a check valve IT NEEDS AN EXSPANSION TANK. I am not trying to sell a boiler or a new heater. I am just giving my opinion. I also have never seen a water heater hold any air in the top to absorb any pressure or temp elevation. I do have 26 yrs of plumbing experiance under my belt.

MSSP
Re: Water Heater Temp/pressure valve leak
JLMCDANIEL wrote:

I'm closing in on seventy years of age, have lived in several homes, and gone through I don't know how many water heaters but have never had to install an expansion tank. I have also never seen NashuaTech give false or misleading advice.

Jack

Jack I have read many of your posts and realize you have a lot of knowledge with your age. The OP said it leaked before and it still leaks. NashuaTech stated most hot systems dont need an expansion tank and most increase in pressure is absorbed by the piping and air in top of heater. I want to know what brand of water heater holds air in the top. I have installed sevral hundred water heaters in my 26 yr plumbing career and have never seen any w/h hold air in top for pressure expansion. Most new water systems have a check valve or a PRV with a check valve and dosent allow back feed into water main, Thus the reaason alot of people need an expansion tank.

As far as dobbs stating "it is just sloppy troubleshooting procedure to shoot off my mouth and insist on additional componants and exspense" And for the new boiler comment that seems like a very mature statement to me. I live in the mid west and op lives in Mass. I was not trying to sell just trying to help
An expansion tank is pretty inexspensive to install yourself. Seems pretty handy for doing what he/she has done already.
To the Gator12, 140 water is pretty high. it can cause third degree burns in about 5 seconds. I hope you find out why the T&P keeps leaking.

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