When I look at any charts online it tells me I want an 80. For the sq ft
Charts like those fall under "Utter Crap!", and are among the WORST methods for sizing equipment on a tight, insulated house.
Heat loss isn't a function of the square feet of living space. It's a function of the exterior surface area of the house, the U-factors of the exterior surface assemblies (which varies by construction type and insulation R-value) and the temperature difference from indoors to outdoors, and the amount of outdoor air leakage.
I live in an antique 2x4 framed 1.5 story 2400' house with 1600' of insulated (but not actively heated) basement, and my heat load is less than 40,000 BTU/hr at 20C indoors, -15C outdoors (my local outside 99% outside design temp). At the water temperatures I'm running in my hydronic heating system I'm radiation limited to less than 45,000 BTU/hr, but the place doesn't start to lose ground until about -25C outdoors, which occurs a couple of times per decade. According to that silly chart I need 72,000 - 144,000 BTU/hr, which is just plain ridiculous. My boiler never even fires higher than ~65,000 BTU/hr, and that's only when somebody is taking a long shower at the same time that the heating zones are calling for heat. (I'm helped out by the drainwater heat recovery unit putting almost half the heat going down the drain going back into the shower.) With all zones calling for heat and no big hot water load it stays under 45,000 BTU/hr.
Suffice to say I would only need the chart's minimum 72K furnace for a 2400' if I left a couple of windows open (seriously!), which I'm loathe do do when it's -15C outside.
ACCA Manual-J uses the U-factors based on construction type and the surface area of each type, along with the local anticipated temperature difference (usually the 99th percentile, some prefer to use the 99.6th percentile, which is probably 2C cooler in your area) to come up with the heat load number. The wild card is always the amount of air leakage, but in most locations as cool as yours people either build it tight enough or retrofit air-seal it to where it doesn't feel drafty all the time, so when using
cheapie or
freebie Manual-J tools, when selecting between"tight / average/ leaky" construction the tool's defaults for "tight" is usually still not tight enough, causing the load numbers to exceed reality, so don't select "typical" or "average"- your house would be miserable to live in if it's that leaky. (Loadcalc
does include Prince Rupert BC in it's pull down menus.)
Bigger is NOT better, and 2-3x too big is the opposite of "comfort", so run the numbers- it's not rocket science, it's arithemetic.
Alternatively you could run an
IBR type load
calculation using a spreadsheet tool as a sanity check. It'll usually overestimated reality too. NRCan's
Hot2000 is another free simple to use load calculation tool.