Water Hammer


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Old 11-07-05, 03:16 PM
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Water Hammer

I'm on the East Coast of Canada and the weather is just at the point where my system is calling for heat. I had a new boiler installed a couple of months ago so we're just getting used to one another. I have 3 heating zones and one for hot water. I have noticed that the zone with the largest and longest loop (bedrooms), and also the one furthest away from the source, is immediately giving a loud "clunk-clunk" sound within a couple of seconds after shut off. It's starting to keep me awake at nights. The new boiler is a High Efficiency Kerr (locally made) with a Grundfos Type 15-42 circulator. Aquastat is set for 150-170 and all zone valves are working properly.
Can anyone suggest a fix for me? Also...I was told to look at the Spirotherm website (Spirovent)..is this something that would work for me? Me being people who don't have air release valves on their baseboards?
Forced hot air seemed so much easier!!
 

Last edited by darstemar; 11-12-05 at 10:23 AM.
  #2  
Old 11-07-05, 04:19 PM
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Water hammer

I would be willing to wager you have zone valves with mechanical electric motors, probably Honeywell. These are the only valves I've heard of causing this noise. Personally I've only encountered this on one system. It was cured by installing a small (homemade) water hammer arrester & an additional air vent at the highest point in the system.
 
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Old 11-08-05, 03:13 AM
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Yes Sir, you are correct..they are Honeywell valves with mechanical electric motors. The only thing that evades me is why this wasn't happening on my previous system (Teledyne Mini-Therm). Smaller capacity, less pressure? Nonetheless, I will take your advice...thank you.
 
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Old 11-08-05, 03:52 PM
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Honeywell zone valves

The only time I have personally witnessed this same kind of problem, I honestly believe there was a small amout of air in the system. After I purged the system, adding fresh cold water, it got worse. I dropped the pressure, added an auto vent & the homemade water hammer arrester. When the system was re-pressurized, heated, & circulation took place, a very short spurt of air was released from the auto vent.
 
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Old 11-11-05, 04:11 AM
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Grady, let me pick you brain here a little bit. This banging is only happening in 2 of the 3 heating zones..the basement and the bedrooms. The living room is working fine. Why is that? I've removed the covers of the valves (so as to watch the movement of the opening and closing of the zone motors) and no matter which ones or how many are working it's always those 2 either independently or together that cause the noise as soon as the demand ceases and they shut. Could the motors/zone valves be faulty here? Again I emphasize that I never had this problem on my previous system.
 
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Old 11-11-05, 06:19 PM
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2 of 3 zones

In the one case where I had the banging problem, it was only one of 3 zones. I would be willing to bet my last dollar, there is air somewhere. Finding & getting it out is another story entirely. I got lucky in choosing the right spot for the air vent & the homeowner thought I was a magician when it was really dumb luck. I would start at the highest point, farthest from the boiler, on the return end of the baseboard.
 
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Old 11-12-05, 05:01 AM
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Grady, I intend to bleed each zone but would appreciate your direction here. I do not have bleed valves so will have to do it at the boiler. I assume I will shut off the power and isolate one zone at a time to be bled (starting with the highest) by closing down the others. Will I manually have to open the zone valve being bled and also do I close the Watts regulator on the return (to the boiler) just before the circulator. I assume I would then just open the tap and let it run off a couple of gallons?. I saw this done once but I cannot for the life of me remember the sequence. What I don't want to do is introduce more air. By the way, the PSI on my system is 13..too low?
 
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Old 11-13-05, 06:54 AM
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Purging system

Purging a system is something done far too often. When you do this, you introduce fresh water (not good). This water, being cold, contains more dissolved gases which will come out of solution when the water is heated possibly causing more of a headache than you now have. If you have any automatic air vents, make sure they are working. If they show any signs of corrosion, replace them.
 
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Old 11-13-05, 04:16 PM
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You may have already done this but be sure that the valves are installed in the proper direction. Those valves will hammer if they are installed backward. Also if you want to do anything semi-major, add a Spirovent air eliminator and a quart of 8 way or any other good air scavenging water treatment. Then don't add water and give the system a week or two to get rid of all the air.

Ken
 
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Old 11-18-05, 08:53 AM
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Question

KField, you are correct, the valves are installed opposite to the feed flow. I had never noticed this before and oddly enough I had never encountered this banging with my previous boiler (Teledyne). What gives there? Also, the genius who installed these valves has them soldered in top and bottom so reversing them involves a little work. One last question, if this is indeed the source of my problem versus air..why would only 2 of the 4 zones be banging? So many questions...so few answers...
 
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Old 11-18-05, 02:36 PM
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Well, theoretically if there is no air in the loop when the pump pushes against the valve it can't compress the water and bang the valve closed. If there is an air pocket somewhere, the valve will compress that air and slam the valve closed. You can try anything you want but things will work better when the valves are installed correctly. It is sad because there are only 2 ways to install them and if you don't know which way is the correct way, why would you just guess?

Ken
 
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Old 11-23-05, 03:45 PM
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OK...OK..Grady and KField..guys, I am really getting confused by this whole hydronics "thing". I have some fixes planned for this weekend and while in a hardware store looking for some parts who should I meet bus a "PLUMBER" self-professed in hot water systems. After a lengthy conversation and a description of my system he tells me the following:
1. My zone valves, while reversed and due to be righted, should be on the RETURN side of the loop versus the FEED side (mine are indeed on the FEED side). This is a major job to reverse them...what say you?
2. He really, really frowns on 90 degree bleeders on the zone rads..again, what say you? His philosophy is turn it up and let it clear itself and then, only then, put a SPIROVENT in if necessary.
I really miss forced hot air...sorry!
darstemar
 
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Old 11-23-05, 04:24 PM
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Valves

Flipping the zone valves over will be job enough. Don't worry about moving them to the opposite end of the loop. They will work ok on either side. In fact some manufacturers of boilers specify putting them on the supply side.

Don't worry about the 90 bleeders. This guy has been reading too many books & not enough time working.

Spirovents do a good job but are expensive.

Once you get the bugs out, you'll forget about the scorched air & love the quiet comfort of hydronics.
 
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Old 11-24-05, 04:35 AM
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I could not have said it better myself, Grady. Flip those valves and get as much air out as possible. Once the rest of the air has worked its way out, don't drain the system unless absolutely necessary.

Ken
 
 

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