Pipes Banging when Zone Valves Close

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Old 12-26-10, 03:41 PM
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Pipes Banging when Zone Valves Close

I have a 3 Zone Hotwater Baseboard heating system that has worked fine for years. Last winter, one of the motors failed on one of the Honeywell zone valves. Since that motor was replaced when that particular zone valve shut off, the pipes clanged. Last summer I replaced all 3 zone valves, the expansion tank, (checked the tank air pressure with a digital guage), then flushed & purged the system. Now my pipe(s) clanging has increased when any zone valve shuts off. If I manually "Slow Down" a zone valve with my finger when it is closing, the pipes are quite. The pipes that are making the noise are not just in the wall but in the baseboards as well.
My guess is that the old zone valve motors may have had some extra drag and when the new motors were installed, the drag decreased and the valves now close faster making the pipes clang.
It there a particular Zone Valve that I can install that is made for systems with loose pipes, or is there some way that I can adjust the return spring on these valves to slow down the closing speed?

Thanks, Bob D
 
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Old 12-26-10, 04:19 PM
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Hi Bob,

When you said you replaced the 'motor', did you mean the entire HEAD? (there IS a motor inside that is easily replaced, so need clarification)

I replaced all 3 zone valves, the expansion tank, (checked the tank air pressure with a digital guage), then flushed & purged the system.
Did you replace the entire valve? body and head?

If the entire valve, are you sure that they are installed in the proper direction? There is an arrow embossed on the side of the valve body that points in the direction of flow.

Checked the air pressure in the tank BEFORE installing on the system?

What pressure did you check for? Does that pressure equal the boiler pressure when the boiler is COLD?

And after flushing and purging, you are confident there is no air trapped in the system? It heats well in spite of the water hammer?

Did you do anything with the circulator when you did this work? i.e. remove it for any reason...
 
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Old 12-26-10, 04:23 PM
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One more question, for the record...

What are the temperature and pressure readings on the boiler gauge?
 
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Old 12-27-10, 07:45 AM
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Last winter just 1 motor in 1 zone valve was replaced, which immediatly started the noise. Nothing else was touched at that time. Then during the summer, I sweated in 3 complete zone valves. I also replaced the expansion tank, (Amtrol Model 30), at that time, which had exactly 12 pounds in it before I installed it. The boiler pressure is between 10 & 12 when hot..I have not checked it cold. All the zones heat perfectly and I hear no gurgling or water flowing through any of the baseboards. I did not touch the circulator (Taco) yet. I am sure all the arrows are pointing in the correct direction of flow: Circulator, Air scoope, & Zone Valves. I did some work in one of the walls and notice that many of the heating pipes are just resting on nails. I insulate and gently secure them as I encounter them as that is how this house was built.
It seems that the pipes that are resting in the baseboards are jumping up when a zone valve closes. Usually the clanging is more prominant when 2 zones are open and just one closes with the other one open.
 
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Old 12-27-10, 11:47 AM
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Boiler Temperature is 190

I forgot to mention that my boiler temperature is set to 190
 
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