Extreme Banging From One Heating Zone


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Old 11-22-16, 10:08 PM
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Extreme Banging From One Heating Zone

I recently moved into a house with a hot water baseboard system and am having an issue with extreme banging noises in one (or more?) of my heating zones.

Here's some info and some troubleshooting I've already done:

I have 3 zones coming off the boiler (downstairs, upstairs, addition). One of the zones (the "addition zone") is further subdivided into 3 separate zones (family room, kitchen, master bedroom).

The "addition" zone has a main zone control valve, and then further downstream it splits into the 3 zones, each with an individual zone valve.

All the zone control valves are Taco 571-2 valves.

So, what happens is that when the "master bedroom" zone calls for heat, there is a massive hammer/banging/shaking/sounds like someone is breaking into the house noise.

I've confirmed that the noise occurs when the zone valve opens, but BEFORE the circulator pump kicks on. There does not appear to be any noise or banging when the valve closes, ONLY when opening.

My theory is that there is pressure building up in between the main "addition" zone valve and the 3 individual zone valves downstream of that valve. This doesn't quite make sense to me though since the piping circuit is unobstructed from the zone valve all the way back to the boiler, so why would opening the valve cause such a noise (it should just flow through?)

I have not ruled out any issue with the Taco valves, but from what I can tell they all work as they should and are not stuck open or shut.

Any thoughts? I quickly threw together a schematic using shapes in Powerpoint and attached to this post.
 
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Last edited by mts37; 11-22-16 at 10:09 PM. Reason: Mis-stated that house was new. House is not new, it is just a new home for me.
  #2  
Old 11-23-16, 07:39 AM
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M,
Do you get heat when the valve opens. Shot in the dark here. The ZV only goes in 1 direction and there is an arrow on the body to show right direction. If that's the only one doing it I would suspect it narrows it down to possibly that ZV.
Hope this helps.
 
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Old 11-23-16, 08:32 AM
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What is the pressure and temperature of the boiler?

I wonder why you have a "main" zone valve followed by three additional zone valves in series? I would manually open the "main" zone valve and leave it open - see if that makes a difference.
 
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Old 11-23-16, 03:55 PM
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I wonder why you have a "main" zone valve followed by three additional zone valves in series? I would manually open the "main" zone valve and leave it open - see if that makes a difference.
x2 .
 
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Old 11-23-16, 10:25 PM
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spott: I've confirmed that all zone valves are installed in the correct direction. Yes I do get heat in the "noisy" zone.

Pressure is reading around 11psi and temperature around 210 when the boiler trips off.

As some of the replies have suggested, I was also thinking of forcing open the "main" zone valve as I did not understand its purpose either (one of many oddities I've discovered in this house..)

Also, I realized I made an error when drawing of the piping diagram. The check valve and expansion tank are switched (expansion tank upstream of the check valve). Not sure if this changes any of the thinking.

I'll try keeping the "main" valve open and see what happens. I'm also sitting here right now and the heat to that zone just came on, with no banging. Seems to come and go (last night it was literally every time the heat kicked on for that zone).

Thanks for the feedback so far.
 
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Old 11-24-16, 07:41 AM
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210 deg F, if that is a correct reading, is way too high and could be related to the pipe banging. Adjust the aquastat to a high limit of 180 deg.
 
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Old 11-24-16, 07:47 AM
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It does make a difference because the only thing that opens that check valve and allows water to flow is when the pump comes for heat. Without the pump operating the hot water from the boiler has no place to go for expansion. The check valve should come after the expansion tank so the heated water has some place to go. There should be no obstructions between the tank and the boiler.
Is your boiler is being used for domestic water also. If so your pressure must be rising when the boiler comes on not being able to utilize the tank for expansion.
I notice the main line ZV before the other 3, although it is strange I didn't mention it because the other zones were working fine so that was not your problem.
If your not using your boiler for hot water you do not need the check valve with the zone valves.
Just a thought. The 210 is quite high and if you don't have a cold start boiler meaning the pumps don't come on with the burner you have all that hot water that has no place to go. It's not at boiling point because of the pressure but it could start to get a little noisy and then when you suddenly open the zone valve you're hearing the effects of scalding water starting to move into the expansion tank and your system.
If you manually open the main ZV before the three it will not solve your problem but it won't hurt anything either.
You could lower you high limit to about 180. You could raise you pressure but not before all the facts are in for safety sake.
Hope this explanation helps.
 
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Old 11-28-16, 08:27 PM
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Ok, so the 210F is only based on the gauge which looks like it has been installed forquite a long time, so i'm not sure how accurate it is.

spott: Just so we are on the same page, the check valve is after the expansion tank.

The boiler does also have a coil for domestic water use.

Also something else interesting to note....I did force open the "main" valve and it did seem to solve the problem, but then I realized that whenever I opened the "main" valve, the circulation pump would come on. I'm guessing one of the three sub zones had to be opening also, otherwise the pump would have nowhere to pump to. I'm not sure if these Taco circulation pumps are positive displacement type or not, but if you deadhead that type of pump it should break something, so the fact that I didn't means the water must have been going somewhere??

Should this be happening when the valve is forced open? I also accidentally disconnected the head of the valve when trying to open the lever, and whenever the head lost contact with the body, the pump also turned on. I thought this was odd.
 
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Old 11-28-16, 08:55 PM
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The head coming off the body should not make the pump come unless you pushed the lever to activate the end switch.
My guess is they have the main line ZV wired so when one of the subzones call that also opens or there would be no circulation to the subs. Depending how it's wired you can try disconnecting the wire from the top terminal(#1) of the main and see if the subzone ZV's activate the burner and pump. If they do put the valve on manual and leave open.
As far as the pump coming on with nowhere to go you would get cavitation which means the water would just sit and eventually the pump would burn out.
Try opening 1 zone and see if both ZV's open. All three should open the main individually. Then try the main manually and see if the subs open up.

"Also, I realized I made an error when drawing of the piping diagram. The check valve and expansion tank are switched (expansion tank upstream of the check valve). Not sure if this changes any of the thinking."
That's where I got that from but I see what you mean now and that's fine.
 
 

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