As a general contractor, I have installed several of these units and even had the pleasure of using one for almost a year in a customers shop I had built. Central boiler is all that I have installed. I cant remember the numbers but the units I have installed have almost 400 gal capacity. 3x3 door with a fire box that was maybe 5 feet deep. They heat up to 153 degrees within maybe 4 hrs with a romping stomping fire. To give you an Idea of capacity I was heating a 40x50 steel shop with 12' tall sidewalls and sprayed in foam of R-14 in the walls with R21 or better in the cieling. We installed floor heat in the monolithic foundation with only 1" of foam on the outside. If I fired the system and made sure it was stoked for a day, in other words maybe say fire it friday night stoke it saturday morning and check and possibly re stoke it in the evening. May not even needed it the shop would remain at 65 for several days and even with temps to zero by friday the shop would still be a comfortable 50 or 55 degrees.
Here is the whole key to this system. Insulate the inside and outside (Stemwall)of your foundation with at least 1 inch beadboard or blueboard make sure you leave a thermal break when you pour the slab dont pour over your stemwall leave it as a floating slab. Tile may be installed with small losses. Before pouring the slab inslulate the dirt closest to the wall with 4x8 sheets of 1 or 2 inch beadboard. Only around the perimeter. The center of the structure must not have any insulation. This will help capture the earths constant temp of 50 degrees ofr better. I use 1/2 kitec spaced usually no closer then 16" OC. My house this time around is spaced 18"oc and then maybe sixteen or closer in bathrooms and kitchen. I also take advantage of passive solar with overhangs on the south side to not let sunlite in after about april untill sometime near the end of october. I do get a litte overheating in the spring and fall but if my overhangs were increased I lose in the dead of winter. So If I come home in april my house could be 85 degrees inside, so I just open a window. Please note that I live in Colorado about 5 miles from the foothills of the Rocky Mountains at an elevation of 8000 feet. The reason my house and so many others that I have built are 1 the sun shining through sothern windows heats the concrete but also the dirt under it providing for thermal mass storage. If you insulate the whole floor you dont get this. Plus place as few windows on the east, west and definetly the north side.
I recently went on vacation for a week and for some stupid reason turned all the valves of to the floor heat system. So my home for over a week had no heat at subzero temps. When we returned at 5:30 am it was 27 degrees outside and the house was 55 degrees inside. Why thermal mass from the dirt under the slab with appropriate insulation on the foundation and some heat gain through 2 4'x6' windows on the front of the house that it!
Back to boilers: If you install the five foot or so of chimney the send you it will back draft all the smoke back down to the ground. dont place this unit on the eave side of the prevailing wind downside. get it out and away in the open taking into consideration the prevailing winds. Also add as much extensions as you can with guy wires. The reason is when the boiler reaches 153 degrees it has a solenoid that slams the damper door shut causing major smoke. They might do better with partial dampening if you ask me.
The wood fired boiler is a good system but with a sothern facing home and a good solar passive and active system there isnt much reason for a big fired boiler. So downsize your boiler a spend money on other areas.
My home also has some other trick active solar heat features which I would be glad to discuss with you.
Recently we finished a customers home. He was amazed that evermorning his home would be 55 or 60 plus degrees inside. Why? only because of the properly insulated foundation. The only south facing windows were 2 3'x5' in the master bedroom. And of course during the construction process the eaves were wide open and we hadnt even pulled a piece or drywall over the attic access.
I have learned the hard way about foundation insulating. The worst I ever did now belongs to the ex-wife. Oh well! Her monthly heat bill in the dead of winter is probably (at todays prices) 250.00 plus a month. My home uses about 75.00 a month.
She heats 1850 sq ft. I heat a 1850 sq ft 2 story with a 700 sq ft garage.
Build a house the pays you back and not so relient on gas prices and youll reap much more then you ever invested
Russ, Colorado
