This one's got me and I need help. New house, two new gas water heaters. There is a pressure regulator on the system. There is also an expansion tank on the system. The TPR valves leaked. They have been replaced twice now and still leak. What's the problem?

Thanks,

Aaron

Sorry all I have is more questions:

1. What's the temperature setting of the water heaters?

2. Is the expansion tank properly sized, installed and charged?

3. Is the regulator installed and adjusted correctly?

I think so.

Aaron

At a minimum you would have to know what the pressure is in the system.

I suppose it's possible to have bad TPRs but not likely.

The expansion tank could be water logged and rendered ineffective.

If it were mine I would put a pressure gage on the tank drain valve and monitor while the heater is cycling.

One other thought. Is the mineral content high in the water? Accumulation of Calcium deposits can cause the TPR to stick.

Michael:

I will do just that.

Thanks,

Aaron

I believe it is one of two things...

1) The thermostat is not working properlty (causing overheating conditions) or

2) Stacking Temperature is probably happening. The "stacking-temperature" conditon takes place when the home users frequently/often use small damands of hot water. This keeps the thermostat cool enough to run the burners longer than needed.

The result is that the cold water entering the tank cannot absorb the diret heat output (down by the burner). The result is that the water surrounding the heated surfaces picks up more heat all the way to the top-- stacking the temperature while creating a fair amount of pressure along the way.

One other question for your... since there is a possibility of frequent short use of hot water, is the home inhabited by a large family? Is there "any" possibility that the toilets could be cross plumbed to provide hot water into the water closet tank? If so, that could be a source of 'frequent' quick use of hot water use.

Richard

__________________
"If con is the opposite of pro, is Congress the opposite of progress?"
Richard Rushing, HCRI
Duncanville, Tx.

I'd bet Michael's right about that.

__________________
Chad Fabry, Rochester, NY
StructureSmart Home Inspections, Inc.
www.structuresmart.com

Double check to make sure that the valves are TPR and not just relief valves. A RV will go off over 30 PSI, while a TPR should be at least 75 PSI. Just a thought.

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Jim Robinson
New Mexico, USA

I agree with Chad, I think Michael has it right.

*IF* the expansion tanks were working properly, they should be able to handle the thermo-expansion, if there is anything wrong with them (water logged, deflated, low pressure, high pressure, whatever) then they will not work 'well', they might work 'somewhat', but maybe not enough.

__________________
Jerry Peck, Construction / Litigation Consultant
Construction Litigation Consultants, LLC ( www.ConstructionLitigationConsultants.com )

Thanks to everyone for their replies. When I get to the bottom of this I'll let you know where it all went wrong.

Aaron