constant circulation for old heat system


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Old 12-13-05, 01:47 PM
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constant circulation for old heat system

A contractor put one of my hot water heating pipe drops in an outside wall during a remodel. It's an old house, and it now dawns on me that this is a not a great idea. The drop is between a window and a door, and I'm not certain that the wall will remain above freezing. I may move the pipes eventually, but I'm looking for a quick solution to avoid possibly freezing the pipes. The house is from the 1850's, and I'm not trusting the wall to be sealed and warm during cold spells.

Is it OK to rewire the boiler so that the pump circulates all the time in the winter? It's a Dunkirk boiler with a Taco 007 pump, and it is a true two pipe system, with oversized piping (2" supply for about total 110' feet, five 1-1/4" drops for a total of 120'). I opened up the control box, and it looks like I could just wire the pump directly to the line power, and disconnect it from the control box switching. Some of the cost of running the pump might be made up for by my losing less heat in the basement to hot water stranded after the boiler shuts down, which is pretty costly considering my fat pipes. It looks like the pump is pretty inexpensive should it burn out prematurely.

Is there any problem with my logic? Any reason I should use antifreeze or some other solution, so to speak? Any suggestions about the whole issue?

Thanks, Josh
 
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Old 12-13-05, 07:24 PM
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Constant circulation

As long as your boiler is set up as a "cold start", the constant circulation should keep the pipe from freezing but I have a concern of over heating (maybe/maybe not). If the boiler maintains temperature even when you are not calling for heat, you will have no control. Your house would get up to a bazzillion degrees, or so it would seem.
 
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Old 12-13-05, 07:40 PM
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No, this boiler fires only when the thermostat closes, and turns off when it opens. It doesn't keep a constant temp, and it has only one zone. After your reply, I wired it up, and it seems to work as desired. I figured it will cost about $6 extra a month to run the pump, but I'll probably save some heat because my pipes are way oversized and I strand a lot of heat in the basement and now (the heat is my second floor apartment).

BTW, I'm looking at replacing all of this oversized and aging galvinized piping. I calculated that more than half my water is in pipes away from the apartment, and the steel 2" pipe creates a lot of mass just by itself. My question is, how do I size the pipe for the heating system? I know this isn't a simple question - could you tell me where to start?

Thanks, Josh
 
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Old 12-13-05, 07:49 PM
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Pipe sizing

Bell & Gossett has a lot of information available on their web site. I'm not sure if there is anything there on pipe sizing or not. Another source might be Burnham's handbook called the "Heating Helper". I'm not sure if that handbook is available to the public or not. It may be on of those "professionals only" things.
There may also be some books available at http://www.heatinghelp.com.
 
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Old 12-14-05, 06:03 AM
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reference site

Thanks Grady. I posted the link to the Burnham Heating Helper pdf below. It is full of charts and information - just what I was looking for.

www.burnham.com/pdfs/htghelper.pdf
 
 

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