I built a new workshop over the last several months and am now considering options to heat it. It is 960 sq. ft. with a 12 foot ceiling. I would only work out there on weekends likely, but I would like to keep it at 5 to 10 *C with the option to bring it up a bit if I know I'm going to be working out there.
I found a spreadsheet online to calculate heat loads and to keep it at 15*C inside with -15*C outside would take about 15000 BTU/hr, but we rarely see temps that cold. I found average temps for this area (the coldest average daily temp is only -3*C) and calculated the annual total heat load for every day under 10*C and came up with 27.5 million BTU.
The first option I am considering is a mini-split heat pump. Mitsubishi has some models that provide rated heat output down to -15*C. The main advantages are no user effort and no floor space lost. The disadvantages are cost of the unit, although I would likely buy from ebay and do as much of the install myself as possible, and complexity. If anything ever goes wrong with the unit, there is very little I can fix myself. I am also concerned with under-performance in case my calculations are off. Electricity costs to cover my annual heat load would be about $400, although who knows where this will go.
My second option is some kind of wood fired boiler. I put 2" insulation under the floating slab foundation and I have pex in the floor, just in case I ever wanted to use this option. We are set up to handle wood as we have an insert in the house and I don't mind the work or mess. I don't have a source of wood though, so I would have to buy it. My biggest concern is the initial cost of the boiler, does anyone know of a smaller, low cost, simple boiler that is still CSA or UL approved? I would build one, but don't want to void my insurance if anything ever happens. I would also like to incorporate storage, but maybe with the thermal mass of the concrete this isn't as important? The wood system appeals to me as I enjoy tinkering and it is simple enough to tweak and repair if necessary. If it gets really cold, it's not too hard to burn a bit more wood, whereas the heat pump may be in trouble, but with a heat pump, I could just turn on some electric heat if I really need it.
Thoughts, concerns, and opinions are much appreciated!!
I found a spreadsheet online to calculate heat loads and to keep it at 15*C inside with -15*C outside would take about 15000 BTU/hr, but we rarely see temps that cold. I found average temps for this area (the coldest average daily temp is only -3*C) and calculated the annual total heat load for every day under 10*C and came up with 27.5 million BTU.
The first option I am considering is a mini-split heat pump. Mitsubishi has some models that provide rated heat output down to -15*C. The main advantages are no user effort and no floor space lost. The disadvantages are cost of the unit, although I would likely buy from ebay and do as much of the install myself as possible, and complexity. If anything ever goes wrong with the unit, there is very little I can fix myself. I am also concerned with under-performance in case my calculations are off. Electricity costs to cover my annual heat load would be about $400, although who knows where this will go.
My second option is some kind of wood fired boiler. I put 2" insulation under the floating slab foundation and I have pex in the floor, just in case I ever wanted to use this option. We are set up to handle wood as we have an insert in the house and I don't mind the work or mess. I don't have a source of wood though, so I would have to buy it. My biggest concern is the initial cost of the boiler, does anyone know of a smaller, low cost, simple boiler that is still CSA or UL approved? I would build one, but don't want to void my insurance if anything ever happens. I would also like to incorporate storage, but maybe with the thermal mass of the concrete this isn't as important? The wood system appeals to me as I enjoy tinkering and it is simple enough to tweak and repair if necessary. If it gets really cold, it's not too hard to burn a bit more wood, whereas the heat pump may be in trouble, but with a heat pump, I could just turn on some electric heat if I really need it.
Thoughts, concerns, and opinions are much appreciated!!
