Relief Valve Leak FAQs#2

TPR Valve leaks at a newly-installed relief valve
TPR Valve leaks even though pressure and temperature are normal
TPR Valve leaks caused by hot water expansion tank failure

Leaks at Newly Installed TPR Valve FAQs

Tip: If the temperature/pressure relief valve is new, is the proper type for your heater, and if you think that the heater temperature and pressure are well below the opening temperature and pressure listed on the relief valve data tag, then take a look at these external causes of TPR valve leaking: thermal expansion leaks and water hammer leaks - detailed

THERMAL EXPANSION TPR VALVE LEAKS

and

WATER HAMMER NOISE

New TPR valve keeps opening and spilling water

New water heater new expansion tank and 2nd new relieve valve why is the valve still opening to release pressure? On 2016-10-24 by Anonymous

by (mod) - what to check first

Anon:

Check the starting water pressure to be sure it's not abnormally high - say over 60 or 70 psi.

Check that the heater temperature is not set abnormally high - safe is to 120F or less unless you also have an anti-scald valve or system installed.

Check that the correct type of pressure relief valve was installed: read the label on your relief valve.

The relief valve's opening pressure has to be correct for the type of heater: a heating boiler TPR valve opens at about 30 psi, a water heater TPR valve opens at about 150 psi, and a steam boiler relief valve opens at just about 5 psi.

Other causes of TPR leaks are described

at RELIEF VALVE LEAKS

We replaced the relief valve but now the new one is leaking!

by (mod) releif valve has been replaced was ok for couple months and now has started leaking again

Ron,

Over at RELIEF VALVE LEAKS we list the common causes of leaks at these safety devices.

When a new valve that's probably intact is leaking I suspect over-pressure or water hammer.

• If your building's water pressure is in a normal range, AND
• if the right type and capacity of relief valve was installed on your heater,

then look further into this possible solution:

HOT WATER EXPANSION TANKS

and at this other cause of relief valve drips:

WATER HAMMER NOISE as if there is a banging sound when you close a hot water faucet that force could be triggering the TPR valve leaks.

Watch out: leaky pressure/temperature relief valves are a safety concern

Plumber keeps changing the relief valve but the new one still leaks

I have problem of my apartment have 2 Ariston 40ltr water heater.b ut I got problem my only one water heater pressure relief valve water dripping.

my plumber change 2 times of pressure relief valve but still same problem when I on my water heater it's dropping after few minutes. How I solve this problem? On 2020-02-13 by Sallu

by (mod) - review the causes of TPR valve leaks

Sallu

Step through the diagnostics at RELIEF VALVE LEAK CAUSES

And let me know what you find.

New water heater relief valve keeps dripping

Hi. I replaced the following.

Water heater.

Expansion vessel

and pressure release valve .

Yet water is still dripping from the pressure release valve. What can I do to stop it? On 2018-09-04 by Ian

by (mod) - other causes of relief valve spilling

Even with all new everything, a pressure/temperature relief valve may drip or release water if pressure or temperature are too high, or if there is an external problem such as water hammer.

I'm assuming (oops?) that you have not set the water heater to an abnormally high (boiling) water temperature. So

let's start by checking the building water pressure to see if it's abnormally high.

Help doing that is at WATER PRESSURE MEASUREMENT 

The other thing you might check is for a water hammer problem.

So also check WATER HAMMER NOISE DIAGNOSE & CURE 

Another possibiity is that your heating boiler expansion tank is waterlogged or has a failed internal bladder.

A similar problem occurs with domestic hot water heaters (geysers, calorifiers) if that heater uses a hot water expansion tank.

See our diagnosis and explanation

at EXPANSION TANK DIAGNOSIS

Then check the causes of leaky TP valves given at

RELIEF VALVE LEAKS

Watch out this is an unsafe condition. The cause of the dripping TP valve needs to be found and fixed and the valve should probably be replaced too.

TPR valve leaked when the water heater was replaced

I just replaced my water heater (electric) and it is was very cold in the attic about 44 degrees.

Water fill was very cold as well. No leaks at fill up and run to get air out of the tank / lines.

Applied the electric and in a few minutes as the tank heated I got some leaks through the T&P valve.

I opened and closed the valve a couple of times. After about 30 to 45 minutes it no longer seems to be leaking.

Is this normal on a brand new water heater? (Dec 5, 2016) Scott

Reply:

Not normal, no, that is, as long as your building water pressure was at normal limits. Perhaps the valve was not properly seated. For safety I'd prefer to replace the valve as I'm not sure what it might do in the future.

But first see THERMAL EXPANSION TPR VALVE LEAKS

Why would a new TPR valve on a new water heater leak?

Great info here, but I have an ongoing problem.

On a fairly new electric hot water heater tank (2 years) I replaced the relief valve because it was leaking and occasionally discharging. However the new relief valve did not correct the problem, still leaks constantly.

So, I replaced both thermostats thinking one or the other was not shutting off the heating elements and it was over heating and discharging. Still, it drips out the relief line.

There is a new expansion tank on cold line.
I could replace heating elements but I do not think that is the problem.

After reading here it seems maybe it is a water pressure problem. But I would have thought the expansion tank would have solved that.
Any ideas? - Richard Stafford On 2020-06-23

by (mod) - undersized expansion tank, water hammer, or one of these other causes

If water pressure is high the expansion tank may be too small,
Or
There may be another cause such as water hammer or wrong TPR valve

Step through the diagnostics at RELIEF VALVE LEAK CAUSES

Replaced the T&P valve, new valve still discharged water

We have well water, we have very little water pressure.

We came home to a t&P valve violently discharging, called Rheem they advised to buy new valve and replace--gave us no instructions-- We just slapped a new one on turned the cold water back on and then immediately followed turning back on the hot water heater the new valve discharged a gushing stream.

Called Rheem again and they said oh no there are steps that must be followed, so we drained the hot water heater and started "Fresh" and followed the steps to a "T".

Now the T&P valve leaks horribly.

Is it possible that all that monkeying around the first time ruined a brand new valve? (Jan 10, 2015) Anonymous

Reply:

I'm not sure what might have happened to the valve - it could have been damaged or improperly installed.

But make a check of the system water pressure to see its level is abnormally high - if water pressure is above the TP valve pressure (or if you bought the wrong type of TP valve) that could be the trouble.
(don't confuse poor or slow flow with low pressure)

Water hammer an also cause a TP valve to leak but that leakage is not usually continuous.

See WATER HAMMER NOISE DIAGNOSE & CURE

Relief Valve Leaks But Pressure is Normal FAQs

TPR Valve Leaks at just 18 PSI Boiler Pressure

I have a pressure relief problem on my Burnham boiler. At first, we found a flooded floor and the plumber noticed a leaky air-vent valve.

I replaced that part and all was well for a week.

Today, I went downstairs and noticed water again; caused by the overflow from a bucket I have under the Pressure Relief Valve.

So, I looked at the boiler pressure and it reads about 18 PSI, which is fine. However, the boiler temperature was 188 degrees and headed higher. So, I shut off the Emergency switch.

I recently had the boiler serviced, the Relief Valve looks fine, so I am not sure what's causing the temperature build-up and what to do about it?

As it is I have to replace one-room of carpeting that initially got wet, I sure don't want to install new carpet and have this reoccur. Please advise. On 2018-02-16 by Vince

by (mod) - check heater temperature, then look for other causes

Vince

You can check the specifications on your temperature/pressure relief valve by reading its data tag. Typically you'll see that the valve will open at 30 psi or at temperatures above 200F. f

So at 188F and 18 PSI the valve should not be opening. Of course the gauges could be off but it'd be unusual for both temperature and pressure gauges to be so far off.

In this case I'd replace the TPR valve. The fact that you had a bucket under it could be a hint that it's been a chronic leaker. Such valves are unsafe.

A simple external visual inspection of the valve is not sufficient.

There are other causes of TPR leaks such as water hammer.

See details at WATER HAMMER NOISE DIAGNOSE & CURE 

If replacing the valve doesn't cure the problem let me know and we'll proceed from there.

See our catalog of all of the causes of TPR leaks

at RELIEF VALVE LEAKS

How to diagnose dripping from the pressure relief valve when Pressure & Temperature are Normal

I have a 31-yeay oil boiler (tankless water heater), which had small water dripping from the pressure relief.

The pressure and temperature was 20 psi and 180 degree.

The boiler does not ignite frequently now because of the beginning of summer season. Water dripping from the pressure relief significantly increased when the boiler was tested to heat the house, and the pressure reading went up quickly to 30 psi.

The water released from the pressure relief contained a lot of yellow residue.

Greatly appreciate if you have any thoughts. (June 1, 2014) Frank 06/01/2014

Reply:

Diagnose dripping TP valves on a heating boiler

If the TP valve is leaking and the heating boiler temperature is BELOW the 200degF limit I suspect either overpressure in the boiler or a defective valve.

The fact that leaks increase when the boiler is heated up is consistent with either of those conditions.

Pressures close to or over 30 PSI will spill the valve.

If your boiler has a tankless coil the coil could be leaking water into the boiler raising its pressure.

With the boiler OFF and cooled down to room temperature, remove water to drop pressure to 12 psi (or slightly higher if your home is more than 3 floors tall).

Leave the boiler off and watch for a pressure increase - that'd indicate a leak into the boiler or a faulty water feed valve.

Diagnose dripping TPR valves on a water heater

Open a faucet anywhere in the building. If the dripping stops, most likely the cause is thermal expansion of hot water.

TPR Valve Discharge Due to Expansion Tank FAQs

Tip: See THERMAL EXPANSION TPR VALVE LEAKS - why the water heater, cylinder, or calorifier relief valve leaks when heating water

and see HOT WATER EXPANSION TANKS for the solution to this problem.

Frequent T&P Valve "reliefs" or discharges traced to expansion tank failure

After installing 100 ft of 3/4" Pex sub floor heating , replacing 24 ft of 3/4' copper base board.

I am experiencing frequent T&P valve reliefs. I have replace the the auto feed and the T&P valve, and purged all the air. Utilty water is high 90 psi. Do need to increase the size of the expansion tank. Or do ypu suspect a different problem? (Nov 28, 2014) Anonymous said:

Reply:

Anon

At 90 PSI incoming water pressure your heating boiler's pressure-reducer / water feeder valve may need replacement OR you may need to install two of them in series as is often done in high pressure locations.

Anonymous said: boiler expansion tank bladder blown during boiler refill at high pressure

Thanks Dan Joe. Your suggestion is something I need do. As it turns out the Expansion Tank bladder had failed, probably due to the 90 psi when refilling the system.

Reply:

Thanks for the feedback anon -that will help other readers. DF

A water logged expansion tank either on a heating boiler or on a domestic hot water supply system (HOT WATER EXPANSION TANKS) can indeed cause the heater's relief valve to drip or leak.

Helpful diagnosis and repair advice that applies both to expansion tanks and to water pressure tanks is found

at WATER TANK BLADDER BURST or LEAKY