normal boiler cycling???


  #1  
Old 12-05-05, 06:10 PM
ktb218
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Is this a boring question?

I am getting no help with my question. Is it too mundane?I just recently had a gas boiler installed, for lots of money. It seems to me that it is "cycling" very often, but I don't know what normal is. The boiler is bigger, physically, than my old one--147,500 BTU compared to 120,000. I'm not sure why, I thought they were going to do the same size (my house, a duplex, is not that big). It is very loud to me, but maybe I am super conscious since it is new.

When it comes on, it is on for a while, 20 minutes maybe (temp. comes up by one degree), then goes off for about 50 sec. Then it comes back on for about a minute. This repeats on and off, 1 minute on, so many seconds off. It does this 'til the desired temperature is reached.

Is this normal cycling, or is it shortcycling? I have left a message for the plumber, but haven't heard back.

Thank you for any help. Kathy
 

Last edited by ktb218; 12-09-05 at 04:31 PM. Reason: no response
  #2  
Old 12-10-05, 05:32 AM
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Nothing is too mundane for me. First of all, if you read most of the requests for info on boiler repacement posted here, one thing that is almost always noted is to ask for a Manual J heatloss calculation before the contractor proceeds. It is imperative if you want to save fuel that the heat output of the new unit matches the requirement of the house. I just pulled out a gas boiler with an net output of 75000btus and replaced it with a boiler that has a 52000btu net output. I calculated the requirement of the house and due to insulation, siding, and windows, the new boiler is a good match. I can't imagine why your contractor would need a larger boiler unless you put an addition on the house and needed the extra output. If the boiler is oversized, it will cycle way too often and that impacts efficiency negatively. The noise is also probably related to a larger boiler than you previously had. There are sometimes adjustments that can be made to change the operating characteristics and possibly your contractor will help out. I suspect that if he did not perform the heatloss calc. he may not be up to the task of adjusting the boiler and controls. Post back after you talk to them and we can see where to go from there.

Ken
 
  #3  
Old 12-11-05, 06:16 PM
ktb218
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normal boiler cycling??? Reply to Thread

Hi Ken--thank you for your reply and info. From what I have been reading and from information from others, I think my problems are being caused by increase in boiler size. The contractor is not replying to my calls.

My thoughts are to get an assessment from another plumber and then decide what to do. There are 6 burners in this boiler and someone said one could be turned off, to decrease the "ferocity"--that might help with the problem. Do you agree with this? I have also spoken with the Peerless Boiler company for their advice.

I have 4 radiators in my place (a duplex,small rooms, 3 floors, but electric heat on the third and also electric in the bathroom). One of the radiators is tiny, so it is more like 3 1/2.

I can't believe I am in this situation!! I am not confrontational at all, but feel I must pursue this legally, along with fixing the problem. I will be curious to see my first gas bill to see what effect this is having in terms of usage.

I am grateful for any other info or advise. Kathy
 
  #4  
Old 12-12-05, 05:54 AM
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You are probably oversized by close to 100,000 btus just guesstimating. You will probably not get any help from your installer if he knows that you are aware of his mistake. If you do, perhaps he could just disable a couple of burners if Peerless approves of that.

Ken
 
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Old 12-12-05, 06:09 AM
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When a thermostat calls for heat, the boiler may be starting from "cold" and takes 20 minutes to heat up all of that water in the entire system to about 180-190F. The boiler then shuts off when the temperature hits the high limit. The hot water circulates in the system and gives off heat to the radiators, cooling it down. When the water temperature drops to the low set-point, typically 20 degrees lower, the boiler starts up again.
Changing the differential, so that the boiler comes back on at an even lower temperature, would let it run longer.
A heating professional needs to look at the whole system before making adjustments. It does sound like the boiler may be very over-sized, but other factors need to be considered: is Domestic Hot Water supplied by this boiler? If so, is it directly (in the boiler) or indirectly (separate tank)? Is there one heating loop that is rather short (not much radiation on it) that makes it cycle so quickly?
 
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Old 12-12-05, 06:23 AM
ktb218
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It is a one pipe steam system--don't know if that would be any different from hot water system. I have a separate hot water tank.
 
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Old 12-13-05, 06:23 AM
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We had a steam system when I was a kid outside Boston, but I have not seen a steam system since then (I have lived in Vermont since high school).
So, I have no experience with steam heating systems and can help no further.
 
  #8  
Old 12-13-05, 06:27 PM
ktb218
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Thank you for checking in anyway. I appreciate it, and also this forum. Kathy
 
 

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