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Bad zone valve

I get a load pipe bang from the forced hot water baseboard. I keep trying to catch it when the zone valve shuts down but a watched pot never boils. I am assuming it is the zone valve shutting down to fast. Is there a way to test this? Zone Valves are taco 571's.

Re: Bad zone valve

I have my doubts that it's the zone valve---this brand & model ZV has no motors, gears or bearings to make the noise you describe.

Your post indicates the noise occurs near the near the end of the heating cycle--which makes the expansion/contraction of the metal pipes suspect.

There's also the possibility there's an air pocket in the pipes that can also make this noise---bleed any air out of the system using the bleed valves on the convectors.

You will just have to maintain a presence in the boiler room at the end of the heating cycle to locate where the sound's coming from with your ears.

Check out the pipe-holder straps to make sure the pipe-holding part is loose enough to allow for pipe expansion when the supply pipes are heating up, as well as cooling down.

Depending on how long the pipe runs are, hot pipes expand & contract as much as 1/2" to 1" during the heating/cool-down process.

Some high-heat wheel bearing grease might help--also check the clearance between the flooring/sub-flooring on the pipe "risers"---the point where they go from the cellar to the first floor.

These openings will have to be widened if the noise is at that source.

Re: Bad zone valve

Thanks NashuaTech, I know of one place where the pipe runs up through the floor and it presses against the sub floor. I will also check the hangers that are accessible in the basement.

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