Hammer Shock


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Old 11-06-06, 11:54 AM
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Hammer Shock

I just replaced my expansion tank with an Extrol #30 and replaced the B&G 100 circulator with a NRF-22 circulator. I've purged the air out of the system, but now seem to have hammer shock. I hear a loud bang once the circulator shuts off. This only happens when the upstairs call for heat, no problem with the downstairs. Is there a way to determine what the problem is? How do you resolve it?

Thanks for the help.
 
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Old 11-06-06, 06:05 PM
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Water Hammer

I'd bet dollars to donuts you have Honeywell or another brand of zone valves with an electro-mechanical motor. Right?
 
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Old 11-06-06, 08:53 PM
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Yes, both the upstairs and downstairs are Honeywell V8043F1036 Motorized Valve (electromechanical). I don't hear the banging with the downstairs, just the upstairs. The upstairs vavle was put in in 1988. The downstairs was put in in 1988, but replaced in 2001. Is there anything I can do?

Thanks
 
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Old 11-06-06, 09:23 PM
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Water Hammer

Your problem is caused by a small amount of air trapped somewhere. If you have bleeders on the baseboard, you can try bleeding them.
The only time I've personally encountered such a problem, I installed a small manual air vent on either the supply to or return from the upstairs loop. It has been several years so I don't remember if it was supply or return. After just a few ventings, the noise went away & has not returned. Purging at the boiler did not work.
 
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Old 11-07-06, 10:53 AM
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I have purged the air several times at the individual baseboard bleeder valves. I can purge the return right before the boiler it comes back into the circulator and then to the boiler. How much water should from the return at any one given time?
 
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Old 11-07-06, 04:44 PM
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Bleeding

If you have been bleeding the baseboard with the thermostat turned up, try it with the stat turned down well below room temperature. Sometimes the velocity of the circulating water breaks up the air pocket so you can't vent the air. I doubt purging at the boiler would help. At least it didn't when I encountered the problem.
 
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Old 11-07-06, 10:14 PM
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So you mean try bleeding the air at the individual baseboards when there is no call for heat? I have purged the air several times at each baseboard during a call for heat until the only thing that can be heard is a little pop sound coming out of the bleeder valve every 45 seconds or so. Someone at work was telling me there is some type of air cylinder that you can put in-line on the supply side or return side to prevent hammer shock. Have you ever heard of anything like that? I never hear the loud bang until the thermostat shut the call for heat off. Is there away to prove if it is coming from the supply side or return?
 
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Old 11-08-06, 07:01 AM
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Water hammer

The water hammer is caused by the rapid closing of the Honeywell zone valves AND the presents of air in the system.

The cylinder you speak of is normally used on domestic water. I've never seen one used on a heating system. Even if it worked, you are just masking the problem. The air has to come out.

Yes, I do mean to try bleeding with no call for heat. You may have to shut the boiler down & manually open the zone valve but try it with the zone valve closed to start.

The "pop" you hear is likely air coming out along with water.

Out of curiosity, do you also have a water conditioner, particularly one to raise the pH?
 
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Old 11-08-06, 03:09 PM
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I tried bleeding the upstairs baseboards under the following circumstances:

1. No call for heat, zone valve in auto, boiler not running. No air came out of any of of the baseboards.

2. No call for heat, zone valve in manual, boiler not running. No air came out of any of the baseboards.

3. Call for heat, zone valve in manual, boiler on. Air came out of the furthest baseboard (last before return). It seems when trying to bleed the air completely out, the pressure doesn't seem to hold enough to keep pushing it out before the flow of water stops and it starts making a sucking noise. When I check the pressue gauge it reads about 10-12 psi. I have noticed that when in this condition and I shut the call for heat off, I hear the bang sound, but the valve is still in manual. Does this point to not being a valve problem?

I then manually let the fill valve input water slowly into the system to bring the pressure up to around 14 psi. By using the fill valve like this is this inserting any air into the system?

Would it be best to completely empty the system at start over?

Thanks for all you help.
 
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Old 11-08-06, 04:59 PM
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Bang

I don't understand how you can get water hammer with the valve open. Water hammer is caused only when the flow of water suddenly stops. With the valve open, you cannot get a sudden stop.
Try cranking up the pressure to 20-25# & bleed some more. To empty the system & start over is shooting youself in the foot.
 
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Old 11-08-06, 05:11 PM
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might be the pump swap

Suggest filling the system, doing a normal purge, then leave it alone to observe and see if the following makes any sense.

The NRF-22 is a much higher-head circulator than the Series 100; nearly double (Ser100 = 8 ft, NRF-22 = 15 ft). So you are probably moving a lot more water with the NRF, and that water is stopping rather abruptly when a valve closes or the circ stops running.

The Series 100 is also a much "flatter curve" circ than the NRF-22. Flatter curved circs generally mean less banging (or potential banging) when zone valves close because there is less of a pressure differential propagating through the system. Moreso because Honeywell valves are prone to banging already.

Compare

http://www.bellgossett.com/homeowners/A-50J-PumpCurve.htm

and

http://www.bellgossett.com/ProductPages/NRF22-NRF-9Fcurve.jpg

Also check out http://www.taco-hvac.com/uploads/FileLibrary/TD01.pdf for more info on this stuff.

If you can't trace the problem to anything else, maybe try a NRF-9 instead, but a Taco 007 would probably be better.
 

Last edited by xiphias; 11-08-06 at 06:05 PM.
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Old 11-13-06, 08:15 PM
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Just got back tonight and you're right, the valve was closing when I was upstairs venting air. I have found the source of the banging. When the valve closes it causes the supply line (pipe directly in front of valve that goes upstairs) to bounce. I have vented this at the bleeder valve, but do not get anything but water. When I take the cover off of the valve and manually opened it and let go, I can see that the gears sort of bounce when it closes. In other words, it might be causing the valve to close, open a little and close. Do you think replacing the valve would end the problem or do you think I need to install a TACO slow opening/closing valve?

I appreciate the help.
 
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Old 11-14-06, 12:48 PM
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I was on the web and found a site where the plumber suggested pulling the cover off of the valve and disconnecting the one spring; therefore, causing the valve to close slower. I did what he suggested and and sure enough it has elimnated the water hammer. Is there a downside to doing this?
 
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Old 11-14-06, 04:29 PM
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Yes. Your high head circulator may push it open when another zone calls. What was your reason for selecting a pump with those specs?

Ken
 
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Old 11-15-06, 04:39 AM
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None. Went to a few sites where they recommend replacing the Bell & Gossett 100 circulator with the NRF-22. I have not seen the valve move when the downstairs valve opens due to a call for heat.
 
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Old 11-15-06, 03:50 PM
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I have two questions. What is a good replacement for American Standard CA-655 Immersion Control? Sometimes the boiler heats up to 195 degrees which is 20 degrees past the set 175 limit. I'm not sure if this unit is going bad or sticking.

Last, is there a good site to visit or some good reading material on how boilers work (from the thermostat, valves, controls and boiler)?

Thanks for everyone's help with all my posts.
 
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Old 11-15-06, 08:08 PM
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Valve movemet

You probably will not actually see the valve move. If the circulator is overpowering the single spring, you will experience over heating of the zone. This is caused by the valve being pushed slightly open & allowing water to flow to the upstairs zone when only the downstairs is calling for heat. A way to check is turn down both stats until the pipes cool then turn up the downstairs stat. Give it a few minutes to get good & hot then feel the pipe beyond the upstairs (one spring) valve. If the pipe remains cool, all is well.
 
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Old 11-16-06, 03:44 PM
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Need Help

Nope, the valve stays shut perfectly.

I now know what is causing the overheating problem. I was fortunate enough to come home and find the boiler temp was at 195 degrees and the circulator running, but both the upstairs/downstairs zone valves were closed and thermostats were off - not calling for heat( + I turned them off). Something inside the Therm Controller Relay box (White-Rodgers 829A-1E5) is causing the problem. The relay contacts that energize (physically come together) stayed made until I tapped the silver plate cover of what I think is the transformer or relay coil. After tapping it, the relay contacts de-energized (came apart). Apparently, this box somehow tells the circulator to run as well as kicking the burners on. Any advice? What can I replace this Therm Controller Relay box with (40 yrs old). Also, any good advice as to where I can read information on the whole process of how all this works together?
 
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Old 11-16-06, 05:06 PM
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Originally Posted by RCJB
Any advice? What can I replace this Therm Controller Relay box with (40 yrs old)...
FORTY ??? Holy cow Batman...

Is the boiler also that old ?

It's GAS fired, yes ?

I'm guessing that Therm Thingy is your AQUASTAT.

Sure there are modern replacements available, but probably not a DIY type project. I would recommend getting a tech in to suggest a course of action. That's a fairly dangerous situation I think, having the burner running un-controlled... get it fixed ASAP please!
 
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Old 11-17-06, 07:10 PM
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Aquastat

It does sound like the aquastat. Replacing is not that big of a deal if you pay attention to the wiring. Don't know what the Honeywell equivelent would be.
 
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Old 11-20-06, 11:59 AM
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Question

I want to replace my White-Rogders 829A-1E5 switching relay with an equivalent relay because it is faulty. White-Rodgers recommends 829A-845, but nobody seems to carry them. So I've been told to use Honeywell's R845A-1030 switching relay - easy to get (I did purchase it). I have a question about how to wire this switching relay.

1. Currently, my terminals labeled Therm (829A-1E5) go directly to the end switch of one of my zone valves and then jumpered over to the other one. So I should be able to directly connect the end switch to the T T on the new (R845A) switching relay, but which T T do I connect the Hot (black) wire to and which one do I connect the Neuteral (white) wire to? http://customer.honeywell.com/Techlit/pdf/69-0000s/69-0790.pdf

2. Currently, terminals 1/3 are jumpered to the Hot (L) terminal (829A-1E5) switching relay. Terminal 2 has the hot (black) wire for the low voltage transformer for the CA-655 Immersion Control. Terminal 4 has the hot (black) wire for the NRF-22 circulator. All Neuteral wires coming into the relay are tied this Neuteral (L) terminal. I guess once the relay energizes, contact 2 makes with 1 and contact 4 makes with 3. Since 1/3 are jumpered to the Hot (L) terminal juice is provided. Which terminals on the new (R845A) would I connect the Hot/Neuteral wires from the NRF-22 to? Which terminals would I connect the Hot/Neuteral wires for the low voltage transformer for the CA-655 Immersion Control to?

Again, any help is greatly appreciated.
 
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Old 11-20-06, 04:16 PM
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Originally Posted by RCJB
1. which T T do I connect the Hot (black) wire to and which one do I connect the Neuteral (white) wire to?

2. Which terminals on the new (R845A) would I connect the Hot/Neuteral wires from the NRF-22 to? Which terminals would I connect the Hot/Neuteral wires for the low voltage transformer for the CA-655 Immersion Control to?

Again, any help is greatly appreciated.
1. The black and white from the end switch are not polarity sensitive. Either way, don't matter... it's just a "dry contact" that switches the relay in the 845 on/off .

2. This is a bit more complicated, because I can't find a schematic for the 1e5 version of your old relay. The W/R recommended replacement is the identical to the Honeywell version as far as pinout goes.

Basically, all your neutrals get connected together, to pin 2 on the new control. (I would wire nut the whites together, and run one pigtail to the screw terminal)

The HOT 120V supply goes to terms 1 , 3 , 5 , and you hook your loads (circulator, 655 transformer) to 4 and 6 .

I _THINK_ this is correct, but like any info from any unknown internet source, take it with a grain of salt... I'm not responsible for any mishaps! I _did_ stay at a Best Western last night though...

Good Luck!
 

Last edited by NJT; 11-20-06 at 04:34 PM.
 

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