Presure Rising

CRP

I have a oil fired boiler that keeps spurting at the pressure relief valve. Relitively new valve and it opens when the gauge reaches 30PSIG as it should. The system is hot water, baseboards and the boiler also supplies the domestic hot water. I drained the system at the run returns and the boiler itself. Refilled and got all the air out. Presure steady at 12PSIG after filling. Once the boiler is turned back on does the presure increase slowly until 30PSIG which is when the prv spurts.Heats the home well and there is ample hot water. I read that if there is a pin hole in the domestic water hot coil this could cause the problem. Any ideas or suggestions would be greatly appreciated.

Alan (California Radiant) Forbes

Expansion Tank

Check your x-tank with all the pressure off the system.  It should read 12-15 psi. at the schrader valve.

Dan_57

Tankles Coil?

You did not say if the boiler had a tankless coil in it.  A pin hole in that coil could raise the pressure in the boiler causing your problem.

Gordan

But that wouldn't only happen when the boiler is firing.

Right?

Mike Kusiak_2

Expansion tank waterlogged?

Does the pressure rise to 30 psi only when the boiler is hot? Return to 12 PSI when it cools down? If so there is probably a hole in the expansion tank diaphragm and the tank is full of water.



When the water in the system is heated, it expands and needs a place to go. If the tank is already full of water, the only place it can go is out the relief valve.

CRP

Expansion Tank

The expansion tank is a bladder type. It didn't have any pressure at the valve so I pumped in 12 psi. My concern is that the tank does not get hot as one would expect. After running the boiler and the pressure rising the tank feels hot only at the top. It is a Honeywell 2 gallon tank. I would think it would feel hot at least to the middle? The tank is hanging from the air scoop which also has an air valve attacked to the top. I pressed in the valve pin (at the base of the x tank) and no water came out, so I don't think it's full of water.

Now for the $64 question:  The tank has a date of 2006 on it's label. Could this bladder be bad if it hasn't been charged to 12psi for a long time? How wouldn't it be getting hot?

I appreciate all your suggestions! Thank You.

billtwocase

recharging

Did you take the pressure off the boiler to test and recharge the tank? You need a gauge to put in 12-15 lbs. While you are charging, you should have a boiler drain open into a bucket, and watch the pressure gauge as you recharge. If it was waterlogged, the pressure will rise until all the water is pushed out while the bladder is filling. Also listen for air going into system while doing this. If so, don't bother, replace it. Always start with zero pressure on the boiler to accurately adjust air pressure in the tank. good luck

Gordan

Buoyancy

It wouldn't be getting hot because it's a dead end - there's no forced flow through it, and since it's hanging downward, and cold water is heavier than hot water, there wouldn't be gravity flow either.