Leaking T&P Valve on water heater

Alan

Sorry, our shop doesn't have a boiler license, so I'm not familiar with the codes on them. First of all your Drawing has the inlet/outlet of the water heater backwards, and I don't see an inlet/outlet on the boiler, so i'm confused on how that system is actually plumbed.


In regards to your original problem, it could be the main PRV has gone out then, so check the pressure on the house at a hose bibb.

__________________
Journeyman Plumber

secutanudu

I'm pretty certain i have the water heater feeds drawn as they are in the house.

As for the boiler, after the baseboard heats, the line just loops back into the boiler (i left it out as i didn't think it applied to the problem).

__________________
Andrew

AllanJ

"This thing" in the diagram is ued to admit more water to the boiler when the latter's level gets too low. I think it is manual although they also make automatic ones. Water does not (should not) go through it the other way, from the boiler back into the domestic plumbing. The expansion tank shown serves the boiler only. You should install another expansion tank in the domestic water system.

If water comes out when you activate the air valve on an expansion tank below or on the side of the pipe it is attached to, most likely the tank is defective and must be replaced. If the expansion tank is above the pipe it is attached to and you can get most of the water out of it with the system turned off, then you can keep using the tank so long as you check it often enough that it does not fill up with water completely as the water will gradually absorb the air without a bladder in the tank separating the water and air.

__________________
The disadvantages of crab apple trees. In summer, the apples are too sour to pick and eat. In winter the birds come and leave dropping all over the place.

secutanudu

Is it just that it is lower pressure than what is normally in the boiler heating loop (hence the low pressure setting on the regulator, about 20 psi), so that water only can enter the boiler system when the pressure drops (ie. water gets low)?

I believe you - but mind explaining how the water in the expansion tank doesn't make it into the water heater?

If I were to install an expansion tank for domestic hot water, where in the line would it go?

Thanks.

__________________
Andrew

AllanJ

The regulator in between keeps boiler water (and in this case the expansion tank contents also) out of the domestic system, I think even if the boiler pressure should exceed the domestic pressure.

Another expansion tank can go anywhere in the domestic system although between the water heater cold water inlet valve and the water heater is the best place.

__________________
The disadvantages of crab apple trees. In summer, the apples are too sour to pick and eat. In winter the birds come and leave dropping all over the place.

secutanudu

I didn't think to check the direction in which that regulator is installed. Or does the pressure reduction occur in both directions?

__________________
Andrew

Alan

I didn't think that pressure regulators had check valves in them

__________________
Journeyman Plumber

secutanudu

If that's the case, how do the two systems not mix regularly?

__________________
Andrew