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[CRJR]

i got my furnace hx and sidearm with new to me power vent hot water heater plumbed in with owb yesterday and the T&P wont stop leaking. it never leaked before so i removed the T&P valve out of the old water heater and replaced it and it still leaks neither one leaked before. owb temp set to come on at 180 and off 190 not shure if it makes a differance any input would be helpful.

[jcc273]

Are you sure the water isn't exceeding or coming close to 210?  Since you replaced the valve with another and are still seeing this i would assume the water is overheating and the valve is actually doing its job. 

Occasionally my damper door gets stuck and my owb overheats causing the T&P valve to open on my domestic water coil.  The influx of cold water is just enough to keep the water from actually boiling but enough to cause the T&P valve to open and form a swamp in the yard.

Maybe try and temp the water to see what temp you are actually reaching.

[Scott7m]

Had that problem a couple times but it was a regulator bad inside my water meter....  Had nothing to do with the stove, I doubt yours does either

[RSI]

Do you have a well or municipal water? 

[CRJR]

i have well water

[RSI]

unless you have a check valve on the cold water line I don't know what would be causing it.
You should be under the temp rating.

[CRJR]

nope no check valve

[Scott7m]

Well, I was assuming you had public water, definitely odd

[baldwin racing]

i got my furnace hx and sidearm with new to me power vent hot water heater plumbed in with owb yesterday and the T&P wont stop leaking. it never leaked before so i removed the T&P valve out of the old water heater and replaced it and it still leaks neither one leaked before. owb temp set to come on at 180 and off 190 not shure if it makes a differance any input would be helpful.

pop the valve couple times make shure there is no dirt in valve normally thats what causes it if it's not boiling over....

kelly

[CRJR]

I did that, no change

[willieG]

if your TP valve is working correctly (and by changing them and stillg etting the same reaction we will assume it is) then it is safe to say you are overheating the water or overpressuring the tank. over pressuring setting is normally around 150 psi. just about impossable on well water system, so lets look at the temp. the TP is likley set at 210 degrees so perhaps your aquastat is not working properly or it is located near a cooler spot in your OWB (too close to return water) and in fact you are heating the water to the 210 mark?

your well system should have a pressure gauge on it, you can see right away  if the pressure is too high

i am guessing yoru water is too hot (perhaps even 200 may cause the TP valve to open slightly

as a test of the side arm perhaps you could shut the delivery water from the OWB off and see if the leaking stops when the tank cools to the normal setting of the water heater

i tend to agree with CRJR, your water is too hot. for a test why not turn the aquastat down to ON at 170 and OFF at 180 go back to the home and run the hot water untill the valve stops leaking and then wait and see if it does it again

[baldwin racing]

I did that, no change

did you let it drain some water off for couple seconds and see if then it would stop?
like pressure getting to high? causing it to leak.... do you have a pressure guage along with temp all on one gage or just temp?