TPR leaking

Lesson learned – check the water pressure over a short time when the tank is getting hot

Inspection produced the following

Water pressure 150 psi after hot water tank ran for a while

Normal pressure 40 psi

Outside pressure 160 psi

Home is 25 yrs old - copper pipe

Regulator, TPR valve, and hot water tank replaced by home owner.

Old tank failed with a leak - New tank failed (Leak) within first year - next new tank was 50 gal in place of a 40 gal

I know the answer but it did take two days to find it – I should have posted this before I started the project for my son


Regulator installed backwards?

Lack of an expansion tank.


I should have posted this first before my son and I spent two days on the problem

My son’s home lacked an expansion tank when the home was constructed

He has been living with a bomb for years

A $10.00 gage would have saved my son two hotwater tanks - two TPR valves - and two regulator

Thank goodness the whole tank did not blow like we have seen on MyTube

Once again put the pressure gage on the system and watch it as the tank comes up to temp

With a pressure regulator installed this is a closed system and the pressure can go to the breaking point

Thank you sir

I hope this information about watching the pressure gets to more inspectors - I never thought of it until it became an issue during my Xmas visit with the son and grand kids

And yes - I took my pressure gage with me to check the system

We thought it was a defective regulator until we had a beer or two and thought about it for a while

Cost of tank was $70.00 - one hr of labor


This is why the PRV should always be one with built in bypass, without the bypass the PRV acts as a check valve, not allowing expansion back through to the main.

The TPR should have protected the tanks and not allowed the pressure to build up more than 125 PSI. :?:

Quick question

How would the relief valve releaved the pressure at 125 psi when the main was at 160 psi??

Bless the code boys and the eng. firms that build the problems

I am now a smarter HI and thankfull that no one got hurt


The TPR OPENS at 125 PSi

And how does it reduce pressure if the system pressure is 160 ???

As I look at it is a closed system and the only releaf is the TPR valve or a leak

Or an expion tank

Pertaining to my “built in bypass” comment, let me back pedal a little because I didn’t read the “160 PSI” part. #-o

Naturally IF the incoming water pressure is higher than the TPR setting, the pressure in the system would relieve before it could overcome main pressure and back out to the street.
A built in bypass isn’t going to make a whole lot of difference other than prevent a closed system BUT still the pressure from expansion couldn’t get any higher than the incoming pressure and any water heater should withstand 160 PSI even IF the TPR valve failed.

Assuming a full sized drain on a properly working TPR valve, the pressure in the system could never get any higher than 125 PSI but a flooded basement - yes.

No problem