Why is this spewing water ?

sldamiano

water is coming out of the boiler from that corroded piece. I’m not familiar with this system.

STEAM DOCTOR

Not enough information provided. Is there an indirect water heater connected to this boiler? Or a tankless coil? Take a bunch of pictures of different things around there, from further back and from different angles. Regardless, you'll need to get a pro in there.

sldamiano

They get here tomorrow. Just trying to get the water flow to stop for now and curious why it’s coming out of that valve

pedmec

Because it's most likely defective and looks like it's been leaking for a long time. But you could also have a chicken or the egg scenario where its discharging because it's doing its job. Either way i think you need to replace it first and then you can continue on to find if there is another problem that is causing it to drip. And add the discharge drain tube. you don't want that to unload wide open and burn the **** out of you.

Jamie Hall

And in case you haven't gathered, that's the safety pressure and temperature relief valve for the whole system. You do NOT want that releasing.

Steamhead

First thing I'd check is the pressure in that Extrol tank. If that's low it can cause the safety valve to "weep".

STEAM DOCTOR

Would have to assume that the valve itself is defective. The boiler is presumably off. Expansion tank is only a player, when the boiler is on. You can shut the water intake.

STEAM DOCTOR

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Lance

Any leak on a sealed hydronic system is subject to a pressure problem or a material or labor defect. test with accurate working gauges. Don't trust what is there. The question of a control leak can be; is it the cause, or its doing its job for safety? never assume it can't be operator or installer error. Also, for those baffling situations, look for that intermittent cause that may not always be present. Remember a valve may seem open or closed but is not. A pump may work, but not enough, a change may have occurred that was not recognized as a cause.

imagine a gas control that overfires twice its rate, but only now and then. I have found check valves stuck, worse, installed backwards. Regulators that failed, expansion tanks that test good but don't actually see the water pressure, or the diaphragm is stuck closed.

Grallert

my money is on the expansion tank

Karl Reynolds

Agree with Grallert. The date code on the expansion tank is the 341st day of 1987. Should change the T&P at the same time.