Water heater temperature and pressure relief (TPR) leaking?

[Tong]

Hi

Thanks in advance if you can give me some info.

My water heater temperature and pressure relief open occasionally.
When it open, it usually filled one or two buckets of water. After that, it is still dripping for a few hours and then stop dripping.

Sometime, TPR is not open and drain pipe and bucket is OK.

The frequency is getting higher and higher. It was about once a few weeks. Now it is about one or two times a week.

Should I replace the TPR? Or the TPR is functioning OK. My area has unusual colder weather than the past.

Thanks in advance

 

[Reach4]

It may be doing its job. Is the dripping after you take a shower or bath? If so, you need a thermal expansion tank. If you have one, replace it.

 

[Sponsor]

 

[Tong]

Oh, Thank.
I am not sure whether it happened after shower or bath.
I do not think that I have a thermal expansion tank.

 

[LLigetfa]

If so, you need a thermal expansion tank.

I would not expect thermal expansion to fill two buckets. A TPR opening from expansion usually releases just tiny amounts. I more suspect over temperature or a faulty TPR.

 

[Tong]

Thanks.

Just did a simple experiment. I turned off the main water valve. Then, the hot water dripping stopped. When I turned on the main water valve, the dripping starts.

It seems that water pressure may be a primary reason.

Also, TPR may not be working properly.

 

[Reach4]

Yes. Get a water pressure gauge with a garden hose thread. Inexpensive.

Bad T+P valve is a prime candidate.

 

[Tong]

Thanks.
I will replace TPR first. It seems that TPR is the primary reason.
As of now, after about 6 hours, the hot water is still dripping. I do not think it is normal.

Here is the my TPR picture. I could not find a match in my local Homedepot.

Or, similar one would work?

 

[Jadnashua]

That T&P valve opens under two (design) conditions:
- pressure exceeds 150-psi
- temperature exceeds 210-degrees F
If the temperature was over 210-degrees, I think you'd know it! You might not notice the extreme pressure, especially if it was caused by expansion.

The third reason the valve may open is if it never properly reseated from when it opened the last time. This could be because of crud on the sealing surface, or mineral deposits on the shank that prevent it from moving through its full length.

If the valve opens for any of its design purposes on a regular basis, it may not reseal. It is a safety valve, and isn't designed to be used regularly on a daily or more often basis.

If you have a closed system (a PRV or check valve), unless something leaks, when the WH heats water, the expanding water needs some place to go. That requires an expansion tank.

You need to find out what your water pressure is doing. Pick up a screw-on pressure gauge with a second, tattle tale hand, then leave it in place for 24-hours or so. Note the pressure on both the gauge and the tattle tale (peak) hands. If it exceeds 80psi normally, you should have a PRV and and expansion tank. If it is below 80, but peaks when the WH runs, you just need an expansion tank.

 

[Tong]

Thank all of you. You guys are great!

Finally had some time to purchase a water pressure gauge from Homedepot.

It reads that outside the house (city line) is about 150 PSI.

I am not sure how to test water pressure inside the house. So, I attached it to my back yard host (my guess it comes from the main water line in front of my house, where I test the reading). It reads 150 PSI as well.

I think my pressure regulator is broken. Is it hard to replace a new one by myself?

Thanks in advance!

 

[Dana]

With a pressure reducing valve on your side of the city shutoff it's not hard to replace. The valve seats can get pitted from corrosion or seep due to embedded grit- nothing lasts forever though in most cases you'd get a couple decades out of it at least.

When you have a pressure reducing valve on the system you really DO want/need an expansion tank pre-charged to your home's water pressure. The thermal expansion of the water can't back out through a pressure reducing valve, so it all has to be accommodated by the plumbing in your house.

 

[Tong]

Here is my water pressure regulator. I thought that I did not have one. But this one seems to be the one.

 

[Reach4]

I am not sure how to test water pressure inside the house.

You can connect the gauge to a laundry tap or the drain valve on the water heater.

 

[Jadnashua]

You can buy adapters, unscrew an aerator from a faucet, and screw it on there. If you choose the drain on the water heater, be careful, it will get hot! And, drain some out before you attach it, or you might just plug up the inlet to the gauge, making it either not read at all, or give you an improper readout. Sometimes, you will be surprised at the amount of crud you get out of the drain of a WH.

Sometimes, people will tap off the main line prior to a PRV for the outside hose bibs, so a reading there may not always indicate what's in the rest of the house.

 

[Dj2]

You have a double union pressure reducing valve. Replace it with the same kind, so you won't have to re-do the plumbing line.
What I don't like is the galvanized T - try to replace it with a brass T, while you are doing the PRV.
Lastly - what is the main line that comes up from the ground? Is that galvanized? If yes - bad news.