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Question:

What causes Emergency Valve on Boiler to Leak?

I have pressure steady at 13psi --- water temp is normal range but the external emergency run valve has been dripping since i turned the boiler on this year? Expansion take was empty, so I forced water through and then drained it and reopened the valve.....I am stuck and getting concerned. Anyone have a suggestion?Would really apprecite it?Additional info:Boiler is a Gas Powered unit by MASTER from the 80's.....

Answer:

The TP valve will naturally wear out over time, if it has never popped open the washer inside of it has hardened, when you opened it it didn't seat properly when it closed back up, causing the drip. This is not an unusual or dangerous condition, the TP valve will usually wear out before the boiler does, it can be quickly and easily replaced. The valve will still function with a leak, but this reduces the efficiency of the boiler. DO NOT, under any conditions, DO NOT plug the leak by plugging the opening on the valve, this creates the potential for a very dangerous condition, let it drip until it can be replaced.
Not sure what you mean by an emergency run valve. Are you talking about a relief valve? This will have a tag on it showing the relief pressure and has a lever to flip to check. Or is it an isolation valve that is leaking from the stem? If this is the case they usually have a packing nut that can be simply tightened to stop it from leaking.

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