I'm new at this "boiler business", but willing to learn. Don't want the learning to cost an arm and a leg. I've been reading and learning here on the forum and am as a result bought a PB 105. For back up I found a used, but sound Liberty Slantfin L-30-H. This may sound bizarre, but I would like to plumb both boilers separately to an Triangle Tube Smart 80 indirect water heater. This heater has a 1 1/2" boiler inlet and outlet and two 1 1/2" DHW outlets and 1 inlet of the same size. It will handle over 300,000 Btu/hr (depending upon delta T). I'll install high temp rads upstairs in a 2200 sq. ft. Cape and radiant under main floor with conduction panels and bubble foil insulation. A third zone will be a breezeway and garage, and a fourth will be a 'Modine' in the basement. Looking at a 30 (or 40) plate HX from the Triangle heater pumped with a delta T variable speed bronze circulator to economize to the heating loop with 3 circulators and a mixing valve for the radiant (mixing return with supply). A zone valve off the high temp circulator can supply the Modine. DHW would be supplied by the Triangle Tube heater with mixing valve. I have a masonry chimney with two 316 stainless 6" flues for the boilers and plan a loss of power heat dump above the Harman with 2 x 6' finned rads. Also will install a Danfoss (or similar) thermostatic valve with a 140 degree outlet for the Harman return water. In summer I plan to shut the Harmon down and use the Slantfin to heat the DHW in the Triangle Tube even though it has a coil. All this will replace a 31 year old inefficient coal, oil , wood hot air Powermatic (currently burning up to 25 face cords of good dry hardwood annually!). So far all I've purchased is the pellet boiler and the Liberty. What I need is some good advice on what the experts might suggest for mods for this system. Maybe scrap it a start a new plan?
