boiler piping size

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steviep

Member
Hearth Supporter
Aug 13, 2008
72
southeast NH
I picked up a woodboiler a while back and my exsisting oil boiler has a 1" pipeing system. Is it ok to run 1" to my wood boiler Properly will be done in copper sence they will be right next to each other. I know 11/4 would be better but I cannot remove the old 1 inch from the existing oil boiler.
 
I do know from reading the pros posts here that pipe size is determined by the amount of BTU's that need to be transfered as well as water velocity and circ sizing requirements. The equation for any heating sizing would start with a heat loss of building. Then the sizing of the boiler to meet that calc. Then the piping and pumping follow. Many questions on piping size here. Old posts have much value on this subject.
Will
 
I was in a class where the instructor - a manufacturers rep stated that whatever size supply and return piping is supplied with the boiler is what you should continue to use for your near- boiler piping. I don't fully agree with this because Burnham for exampe uses 1 1/2" pipe on their V8 series boilers right throuh the different sized product line, which makes sense for manufacturing purposes, but does not correlate with flows actually required.

All that being said on our installs we use 1" pipe up to 80,000 btu
1 1/4" pipe up to 140,000 btu
1 1/2" pipe up to 220,000 btu
2" pipe up to 450,000 btu ( not too many residential applications call for this )

Bottom line is if you're trying to push more than 80,000 btu through that 1" pipe, you will have to increase the flow rate, and at some point that becomes counterproductive, and eventually damaging to your system. The other side of all of this , and we see this all too often is oversized boilers. If your load is not greater than 80,000 btu, but your boiler is it doesn't matter. in other words if you don't have a way to use 80,000 btu, and you're capable of making that or moreit won't matter if your pipe is undersized. I know this is a simplistic approach, but many systems are not designed, they are simply put together in the field by an installer- up to his/her level of incompetence.

Lastly, you can "push" more flow (read btu) through a smaller opening for a short distance. Bernoulli's principle goes into this, but for our practical applications this should only be considered (IMO) for an application such as an existing undersized T with a reducing coupling to get you to the correct size needed.

Hope this helps
Chris
 
Ok I looked at my system , it is a Burnham V13A , I believe 89,000 btu ? I does have 1-1/2 in and out . The proplem is the output they origanally put an 1-1/2 to 1" reducer that I can't seem to get out and I have been told that if not done right you can dammage the threads in the boiler. The input is already 1-1/2 to the circulator, 007 taco. My house is 24 x 40 ranch with a walk in celler that I heat with a modine off my boiler, I would like to someday install a couple of steam radiators down there someday,. As far as the wood boiler I do know it is a Deepwood 7848 but that is all I know , I don't know the BTU's .If it was electrical I would have no proplem as I am an electrician, and I do work with a few good Plummers but the one's I would allow in my house are busy. I hope this help everyone help me.
 
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