New Pressure Relief Valve Leaks

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Hayden

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My water heater TPR valve was leaking - not much - couple ounces/day. I replaced it.
It's still leaking. Not quite as much, but it still dumps a couple ounces/day. Even if both temperature settings are set low (both the same, 120 degrees).

Does this mean the water heater is bad?

It's a Westinghouse 40 gal electric unit - probably about 8 to 10 years old.
 
Is the water coming out of the pipe attached to the T&P valve, or from somewhere else.

Also, what is the temperature of the water coming out of the closest faucet? Do you know what the water pressure is in your home?
 
Do you have an expansion tank? Does it still have air in it?

If you have a pressure regulating valve, on your feed line, and don’t have a functional expansion tank, the expansion of the water as it heats, will force it out of the TPV.
 
FishScreener said:
Do you have an expansion tank? Does it still have air in it?

If you have a pressure regulating valve, on your feed line, and don’t have a functional expansion tank, the expansion of the water as it heats, will force it out of the TPV.
Click to expand...
Can you educate me on why having a PRV will cause this to happen? If he had an expansion tank and no PRV, would it not happen?

I don't know if it is new code or possibly a regional thing, but I rarely see expansion tanks on water heaters.
 
An expansion tank is required if there is something in the cold water supply line preventing the water system from expanding back into the city water supply.
A backflow preventer for example or a PRV. Although SOME pressure reducing valves can allow a small amount of expansion to go back through it, it may not be enough to prevent over pressurizing of the water system due to thermal expansion. Many PRV prevent backflow, which is inherited in their design.
 
Thanks for the education! I never knew that.

I do not have an expansion tank on my water heater. Is there something to be gained by having one if I am not having any problems?
 
Let me first say that I don't know if there are any codes that require an expansion tank for a water heater, in the absence of some type of backflow device.

No there's really nothing to be gained by having an expansion tank if the system is open to the water source.

Here are a couple of examples of what the codes say...
 

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Hayden
When you replaced your T&P valve, did you by any chance open the valve?
If you did, that may be your problem I am not ruling out the discussion you had with Diehard
this is a different issue altogether. The T&P valve has a rubber diaphragm internally.
if 1 speck of sand gets on the wall of the rubber, diaphragm the unit will leak
There is a hack that works 50/50
tap it smartly with a wrench. that has been known to work



 
I agree with the above suggestion to try to clear a possible speck which may be causing a drip.
If the tapping doesn't help, open it up a few more times.

There are some that say you should never open that valve as that may cause the lodging of some foreign mater and cause a leak. This can't be disputed, however, you should also be aware of the following....

1. "Water heater manufacturers' installation instructions for at least some water heaters advise building owners or maintenance personnel to manually operate the TP valve at least once a year to make sure it is working properly."

2. How it is leaking water can be an indication of the possible problem/cause. Steady drip vs. intermittent discharge. I don't think this needs further explanation.

3. The release lever was put there by the manufacturers for a reason.

Just additional food for thought.
 
I have opened the T&P valve. I believe testing the valve was part of the install instructions.
There is no expansion tank.
I see no valves (PRV or pressure reduction) other than the shutoff valve.
Both thermostats (top and bottom) are set about 140 degrees.
The T&P valve is rated at 150psi/210 degrees.
Max water temp at nearest faucet is 125 degrees
I don't know what the water pressure is from the city lines. I don't have a gauge.
I will tap the valve but I will be pretty timid about it since I don't know what is inside the heater. Are the innards pretty robust?
I haven't heard anybody suggest that the heater needs replacing. Is it safe to assume the problem is something else?

Thanks to all for your input.
 
Typically when one decides that a tank type water heater needs replacing is when it is a leaking tank(not leaking from pipe), or if it felt that it has outlived it expected life and there are some problems with it. Such as problems with the gas valve or thermostat controls, heating elements, electrode. Things that could be replaced but due to age one decides not to push their luck any further. Do you know what the warranty period was on the unit, as it common for them to go shortly after that period, if not sooner?

In your case it's still somewhat questionable. If there's water coming out of the P&T relief valve it's either reaching it's set temperature relief setting or it's pressure relief setting or it's defective or there's something keeping it from seating properly.

Since it's a new valve we are assuming it's not defective. It sounds like it's not reaching it's pressure or temp relief limits. So that only leaves something may have gotten lodge in the seal.

But I still must ask, is it a relatively constant drip or a periodic release? As a constant drip would indicate something keeping it from sealing properly. While a periodic small release would indicate, to me, a possible/occasional high pressure release.

150psi PSI is pretty darn high for city water pressure, even at night when it typically can rise. But it wouldn't take much to pick a pressure gauge that has a second needle that records the highest pressure it sees during a period of time before resetting it. It simply screws on to a hose connection. A hose bib or the water heater tank drain.

Something like this. Doesn't have to be super accurate.
https://www.homedepot.com/p/Winters...olh9R4iBKEFK80Uqp4UaAqmDEALw_wcB&gclsrc=aw.ds
 
Hayden said:
I have opened the T&P valve.
Click to expand...
Then you have no idea if it is trash on the seat of the diagram or if you have other problems
change out the T&P again
This time DO NOT open it. then you can tell if you have other problems

install a memory gauge on your washing machine hose thread connection

https://www.freshwatersystems.com/products/water-pressure-gauge-with-hose-connection-0-300-psi-with-red-max-indicator?variant=13249865678891&c1=MSN_SE_NW&source=PLA_USA&cr2=shopping__-__nw__-__usa&kw=1288_1741_0&cr6=pla-allproducts&cr7=c&msclkid=c9198468f3681c13696bd9cdf22c6323&utm_source=bing&utm_medium=cpc&utm_campaign=Shopping - NW - USA&utm_term=4582352153658418&utm_content=All Products
Water pressure gauges with garden hose connections are used to test water supply pressures within a distribution system. Its red indicator hand holds at the highest reading registered for detection of thermal expansion pressure surges. It features a black enamel steel case, acrylic lens and 3/4" garden hose connection. Available up to 300 PSI (21 bar) pressure rating scale.
 
Last edited:
I tapped the valve yesterday and - so far - things look drier. I'll wait a couple days. If still leaking, I'll replace it again and not touch it. I'll also buy a pressure gauge. Then I'll report back.
 
Sounds good!

Just out of curiosity, was the previous release of water a relatively constant drip or periodic small release?
 
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