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[EE Farm Boy]

Newbie here so lots of questions.  I am an Electrical Engineer so I normally have to analyze something 10,000 different ways before I pull the trigger so I apologize.  I am going to install an P&M outdoor wood boiler before next winter so I am in the planning phase right now.  I would like to get everyone's opinion on which size BL boiler I need.  Here are the details of my setup:
I live in NC so the winters are not too harsh normally.  Outside temp are around 30-40 degrees with nights getting down to the teens.   I have a 4 ton heat pump for downstairs and a 2 ton unit for upstairs but it is just not cutting it as we have to burn gas logs 24-7 on a thermostat.
I built the house in 2003 contracting out myself so it is insulated fairly well.  When I calculated the needed BTU's, on average is around 130,000 BTU/Hr but if I use the lowest temperature around 10 degrees it comes out to 180,000 BTU's.  I have a force air system which I will install heat exchangers in.  I have two units, one for the downstairs, and one for the upstairs.  Total square footage is 3,000 on these two levels.  I currently don't heat the portion of the finished basement but would like to with the boiler, another 800 sq ft.  I would also like to heat the garage, 25 x 25 on occasion.  I also have an outside post frame building that 36 x 50 with 14.5ft ceilings.  Insulation in this building is only R9 with spray foam closed cell.  I plan to keep this building around 40 degree but when I want to go work on things maybe twice a week then I will turn up the heat to make it comfortable, but only twice a week.  The distance from the boiler to the house will be 170ft, then another 60ft in the basement to where I want to put in a manifold.  The distance to the post frame building will be 70ft from the boiler.  Once at the manifold, I have only a few feet to the heat exchanger for downstairs unit and water heater.  I have to then go from the manifold to the upstairs unit which is another 80ft.  I hope this gives the details of my setup.  I plan on using 1" Logstor insulated Pipe.  I was recommended to go with the BL34-44 but I know that most of the time I may not use all of the BTU's and from what I read it is not good to oversize the boiler therefore I am asking what others think.  We farm on the side, so no neighbors and plenty of wood from our own land, mostly hardwoods.  I have already started preparing my wood, up to about 3 1/2 chords so far.  I plan on taking lots of pics and keeping track of the install.  Any pointers and suggestions are welcome. 

Thanks,

[slimjim]

As a sales guy I would want to sell you the bigger boiler, as a service tech for P+M, I want to sell you the smaller boiler and let you run it hard, will you be OK in a cold snap with your existing system helping the wood boiler keep up, here in the northeast we figure that your max BTU load is only about 2 weeks long, if you think you can be OK with that use the smaller unit, if not get the larger unit and perhaps you can find something  else to use heat for to work the unit, you are in my opinion right there at the sweet spot.

[EE Farm Boy]

Thanks Slim Jim.  During a cold snap, I could always shot off the 36 x 50 garage, most of the time, the cold is at night and I would not be out there anyway.  When you say run the smaller one hard.  How will this effect burn times.  I mean, could I still get a 12 hour burn with hardwood?  Not really interested in having to go out in the middle of night to fill the stove.  What I plan to have connected to the boiler:
2 heat exchangers in the force air
A stand alone small heat exchanger for finshed basement
A stand alone small heat exchanger for insulated Garage 25x25 which is connected to the house
Flat exchanger for Hot water in the house

1 large stand alone fan/ heat exchanger for the 36x50 building
Flat exchanger for hot water in building as well, in case I want but there again, only out there on the weekends.

Thanks,

Thanks,

[EE Farm Boy]

Another quick question.  When P&M specs the small Ultimizer at 225,000 BTU's, how accurate is that number?
Also, how much do you normally have to account for hot water in the house with a family of four?  I have heard 50,000 BTU's.  On the coldest of nights, 180,000 + 50,0000 would put me right at 230,000 but this would be very seldom if any at all.

Also, how would you tell if you need to cut back some of the other heat exchangers and or building?  Could see what your return temps to the boiler are and if to low then cut some of the other nice to have's off. 

Thanks,

[slimjim]

These are all great questions, let me direct you towards another line of thinking, Do you have a backup heat system now? if so then you can use those Aqua-stats that I post about to allow your existing system to help out on those really cold nights and for any time that your boiler goes down or you forget to put wood in the boiler, it's a fact that most homes current heating systems are severely oversized and are set up to heat the entire load all on their own, very few installers ever think about sizing smaller and using multiple systems in the extreme cold, a typical winter only has about 2 weeks of extreme cold and I think most homeowners would be happy with burning some oil or gas to help out in those times to help out with the extreme heat load, design and controls will be key, you could control those areas like the shop to automatically shut down when the water temp on the boiler drops as well, by controlling the heat zones you should be very happy with the smaller unit and it's burn times, I would far rather you feed the boiler a bit more often than oversize it and it just lays there smoldering.

[EE Farm Boy]

ok, thanks, my mind is set on the smaller unit.  I feel more comfortable with the smaller unit as I want to make sure I am able to burn it hot to prevent issues.  I do have back up, it you want to call it that, its a heat pump with back up electric and we have gas logs in the living room. 

Since I have no dealers in my area, can anyone recommend a good dealer to work with or should I just work directly with P&M?  When I spoke with P&M, they said I can work directly with them, just wondering where the best source of knowledge would be to design the system the correct way. 

Thanks

[slimjim]

I am a troubleshooting rep for P+M and will be happy to guide you through your install, I would like to do it on the forum as it will benefit others at the same time, I will PM you my contact info for those quick questions that you need a quick answer for