Pipe hammering

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Old 08-12-13, 10:51 AM
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Pipe hammering

Hi all, First timer here.

I have a hotwater furnace with 3 zones for heating and a domestic hot water heating with a 40 gallon tank. My problem is when my the furnace is running ie, one of the zones call for heat and then my domestic hotwater heater calls for heat I get a tremendous hammer or banging as the 3 way valves closes for the heating and opens for the domestic hotwater. Any thoughts?
 
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Old 08-12-13, 11:22 AM
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Thanks for the reply...
The circulating pump is what is running and when the DHW calls for heat the 3 way valve which is Normal close opens up to let the heated water move through the hotwater tank. Column closure water hammer? can you explain the term and fix?
 
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Old 08-12-13, 11:29 AM
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The 3-way valve's actuator seems to be too fast acting. Do you have a relay control center that controls the zone valves and that has the provision for designating a priority zone? You could then eliminate the 3-way valve and install a regular zone valve for the water heater.
 
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Old 08-12-13, 11:39 AM
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Thanks....
Could the 3 way valve be installed incorrectly? That was one thought I had about it. I will check on the relay control center question. If I understand you the DHW would be the priority zone. From What I understand that it how it is set up now but with the 3-way.
 
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Old 08-12-13, 02:43 PM
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Tell us the boiler make/model and give us more details about how it's all piped up...

Is this the Weil-McLain with the 3-way valve mounted on the boiler by any chance?

Pictures could help.
 
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Old 08-13-13, 08:05 AM
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The boiler is a Burnhan ESC 3, with a Triangle Tube hotwater tank. I will try to send pictures next time. Any thoughts would be appreciated. I have my HVAC guy coming tomorrow to check it out. Are there any obvious things I should ask him about?

Thanks
 
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Old 08-14-13, 11:40 AM
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Circulater Pump/Pipe Hammer

Hi all,

Well my service person was out this morning to check on my pipe hammering problem. He seems to think it is happening because the circulating pump is running when the 3 way valve is opening when the DHW calls for heat. It only happen when the zone valves are calling for heat too. He thinks a delay relay is needed. I guess when the DHW calls for heat the circulating pump stops for 30 seconds or so then starts back up. Makes sense to me..... how about to you experts. Do you think this something that should have been designed into the system?

Thanks for your thoughts
 
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Old 08-14-13, 04:30 PM
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My personal opinion is that adding delay relays on the pump in order to compensate for some other problem is nothing but a band-aid.

Without knowing much more about how your system is actually piped, we can't really come to any kind of meaningful conclusion. Anything we say would be a WAG.

That said, zone valves don't hammer when they OPEN, only when they CLOSE... BUT, with a 3-way, that valve is doing both at the same time.

What you are saying I believe is that if the indirect calls for heat all by itself... no other zones calling, there will be no hammer.

If there is no indirect call for heat, the opening and closing of the zone valves never produces a hammer.

You will ONLY and ALWAYS hear the hammer if a zone is calling for heat and the indirect then calls for heat.

Is that correct?

I'm most curious as to why the installers chose to use a 3-way valve rather than treat the indirect as 'just another zone'. I can't see the necessity of the 3-way.

Me myself, I would probably re-pipe it and lose the 3-way and pipe the indirect as it's own zone.
 
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Old 08-14-13, 06:14 PM
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I would probably re-pipe it and lose the 3-way and pipe the indirect as it's own zone.
Which is essentially what I said in Post #3.
 
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Old 08-14-13, 07:06 PM
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Yep, you sure did! Great minds think alike!
 
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Old 08-15-13, 11:36 AM
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NJ
I like WAG or in my field SWAG,

That is correct...only when the indirect DHW and heating zone(s) are both calling for heat is when the hammering happens. I mentioned what gilmorrie suggested in post #3 and I think the service guy is considering that option. As to why the installer went with a 3 way valve I believe it is in the installation manual to install it that way. I have a couple photos I will post soon to get your impressions. Other than the hammer noise we have been pleased with the system. I might disconnect outdoor reset unit to see if I can get longer run times but that's another discussion which has been covered here before. Seems it almost always comes down to oversized boilers.
I mentioned that to service guy and all he could do is shuffle his feet and look away.
Thanks for your help.
 
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Old 08-15-13, 02:41 PM
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As to why the installer went with a 3 way valve I believe it is in the installation manual to install it that way.
I just looked through the manual and don't see that...

Seems it almost always comes down to oversized boilers.
Yours is probably not GROSSLY oversized, unless you are heating an 800 sq ft bungalow.

Is your ODR set up properly with the correct design temp, etc?

I mentioned that to service guy and all he could do is shuffle his feet and look away.
Service guys don't like it much when the customer is intelligent and informed!
 
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Old 08-16-13, 11:11 AM
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Photos of my system

Thanks for all your responses.
Here are three pics of my system. Feel free to critique/comment
 
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Old 08-17-13, 12:10 PM
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I have no idea why a 3-way was used, other than the fact that it was their idea of how to 'prioritize' the indirect water heater.

This could have been done more sanely with a Taco zone control panel and one more 2-way on the 'manifold'.
 
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Old 08-17-13, 03:51 PM
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I think the simplest approach is to replace the 3-way with a regular zone valve, and add a zone control box, with the indirect set up as a priority.
 
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Old 08-18-13, 08:56 AM
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I think so too.

Sure, one could possibly 'fix it' with some complicated jury rig of wiring and delay relays, but it wouldn't be the right way.

The way this is installed the hammering is clearly due to an improper design.
 
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Old 08-18-13, 04:18 PM
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Academic Question

The water hammer happens only when there are heat calls in progress when the 3-way cuts over to supplying the indirect. So, the water hammer occurs where? At the 3-way valve when the flow to the heating zones is "suddenly" diverted?

My puzzlement is that I thought 3-way diverter valves shut one discharge port while opening the other discharge port, sort of in a phased timeframe - when one port is, say 90% open, the other port is 10% open, etc. But, I guess if the actuator is very fast, strange things can happen?

We don't know the model of the 3-way valve, but it looks like a Honeywell.
 
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Old 08-18-13, 08:09 PM
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Gil, I think what's happening is that since a heating zone valve is still open (remember it ONLY occurs when there is a heat call already in progress) and the circulator is running already, the water moving through the port going to the heating zone slams it shut...
 
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Old 08-19-13, 02:58 PM
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Thanks for your thoughts. I will pass it on to my HVAC guys. The 3 way valve is a caleigh (sp).
HJ... you mentioned not seeing the 3 way in the installation manual. I think you are correct. When I try to decipher the piping schematic specifically figure DW-5 it appears to show a separate circulator in the system for the Indirect system Any chance you can look that over and comment

"I think the simplest approach is to replace the 3-way with a regular zone valve, and add a zone control box, with the indirect set up as a priority."

Read more: http://www.doityourself.com/forum/bo...#ixzz2cSF59jm1
 
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Old 08-19-13, 03:57 PM
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When I try to decipher the piping schematic specifically figure DW-5 it appears to show a separate circulator in the system for the Indirect system Any chance you can look that over and comment
As I recall (I didn't look back again) you are correct.

It's usually recommended that an indirect be on it's own pumped zone, but it's not a 'show stopper' if it's not, as long as 1" pipe and a 1" zone valve is used to connect it. The idea is to maximize flow to the water heater. One might not get adequate flow if 3/4" piping and a zone valve is used, ESPECIALLY if the water heater is not set up as a PRIORITY zone (meaning that the system shuts down the space heating circuits during a DHW call and devotes it's all to the water heater).

Priority can easily be established by the use of a 'zone control panel' such as a Taco ZVC series.

ZVC404-4 - Taco ZVC404-4 - 4 Zone Valve Control Module
 
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Old 08-19-13, 04:17 PM
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I might consider doing something like this for the least invasive method of repiping.

Cut out the 3-way, replace with a TEE, install a 2-way on the branch to the water heater, use a pair of 45's to realign with the pipe to the space heating.



Then wire up the ZVC 404 setting the indirect to priority and call it a day.
 
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Old 08-20-13, 10:38 AM
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Thanks again for your comments/thoughts. In the setup you have shown in the photo would the space heating zone valves close when the DHW indirect zone valve calls for heat? The circ. pump doesn't shut down for a short period does it? I believe the wiring/electronics for this boiler already has the indirect DHW priority preset somehow. I need to call my HVAC guy.
 
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Old 08-20-13, 03:00 PM
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In the setup you have shown in the photo would the space heating zone valves close when the DHW indirect zone valve calls for heat?
Priority would be a function of the zone control panel. Is the switch inside is set to priority, then yes, the space heating zones would shut down when there was a DHW call.

The circ. pump doesn't shut down for a short period does it?
No. If the space heating is already calling for heat, and a DHW priority call comes into the panel, the space heating zone valves will close, but the pump will continue to run.

I believe the wiring/electronics for this boiler already has the indirect DHW priority preset somehow
I would need to look at the manual again, but you could be right about that.

If you use the ZVC panel you won't need to use that feature in the boiler.

There are other ways to re-pipe and correct your problem, but I believe that what I've outlined may be the most cost effective, with the least amount of labor time in re-piping.
 
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