I had a new hot water boiler installed with three new honeywell zone valves. The system works fine except for one problem. The pipes bang at the end of a heating cycle. I had the system purged at least five times. The system is quiet for the first two days and then the banging starts again. The banging appears to be the worst during the early morning hours. One plumber suggested a 4 zone controller by macduffco mfg. This controller will allow the honeywell zone valve to shut down slowly[15 sec.] and thus eliminating the water hammer. I would appreciate your comments and your suggestions. I already had four different plumbers look at the system and no one will guarantee a fix.

Have you read the post below?

https://www.askmehelpdesk.com/heatin...pes-53625.html

Hope this help!

A follow-up question. The answer didn't solve my issue. My new hot water heating was installed with a smaller expansion tank on the return side. Will this affect my pipe banging issue. It was also suggested to imploy a spirovent in my system to eliminate all area air related problems. Will this help?

I don't think the smaller expansion tank causes the banging problem, it will increase the system pressure when heated, do you know what is the system pressure are when heated and when the system is cold?

Should the expansion tank on the supply side instead?

The spirovent will definitely help if you system pressure is within the system requirement.

The pressure ranges from 14psi. To 20psi. The temperature is 160 deg. And the aquastat is set at 180 deg. I noticed that the banging occurs at end of a heating cycle of one zone when the two other zones are off. If more than one is open and calling for heat the banging doesn't occur.

Sounds like the pressure is on the low side, is it easy to fill the system to 20 psi when cold and give it try.

At the end of the heating cycle, if the zone valve closed at the same time than it implies is water hammering.

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Originally Posted by pault

I had a new hot water boiler installed with three new honeywell zone valves. The system works fine except for one problem. The pipes bang at the end of a heating cycle. I had the system purged at least five times. The system is quiet for the first two days and then the banging starts again. The banging appears to be the worst during the early morning hours. One plumber suggested a 4 zone controller by macduffco mfg. This controller will allow the honeywell zone valve to shut down slowly[15 sec.] and thus eliminating the water hammer. I would appreciate your comments and your suggestions. I already had four different plumbers look at the system and no one will guarantee a fix.

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I have the same problem. My service company changed the circulator to a grundfoss which has three settings - high, medium and low. On the high setting the banging is the worst. On the low setting the banging still occurs but muxh less frequently and much quieter. Still trying to find the complete solution if you come up with something that works.

Also, I have a couple of zones which use a Taco zone valve controller. The Taco closes much slower and the these zones to not bang at all.

Turns out that my Honeywell zone valves were causing water hammer. I just changed my Honeywell zone valves to Taco zone valves which close slower. It has been two days now and the banging has gone away.

While I changed the valves from Honeywell to Taco and it seems to have worked, I was told by a HVAC person that sometimes removing the springs from the Honeywell zone valves works. Apparently the valve open and close without the springs but slower than with the springs.

Good luck.

After moving into a older condo with hot water heating, I had banging pipes after each heat cycle. It turned out that the zone valve was installed backwards. The plumber/mechanical person reversed the zone valve--things seem to be better.