80,000 btu furnace 2200 sq ft

[Plumber69]

House is 2 floors, 2200 sq ft, all new windows and insulation. No attic if makes a difference. Will 95 efficient do? 2x4 exterior walls

 

[Dana]

Any 80K furnace at any efficiency is ridiculously oversized for any 2200 house that has some fluff in the walls and attic, and glass in the windows. Sounds like you have both, in which case you really don't want an 80K furnace!

At Prince Rupert's 99th percentile temperature bin of ~-10C/+13F the actual heat load of even a reasonably tight 2x4 /R13 type house with clear glass (no low-E) double panes will be under 30,000 BTU/hr, maybe even under 25,000 BTU/hr.

If you have a heating history on the "before new windows & insulation", run this math on last winter's fuel bills using exact meter reading dates & amounts, and the nameplate efficiency of the old equipment to MEASURE the heat load in it's prior state.

Barring that, use a Manual-J based online freebie tool such as LoadCalc, to estimate the heat load. Be sure to select "Tight" for construction type or it's going to oversize you by quite a bit.

The ASHRAE recommended 1.4x oversize factor from the 99% load should be viewed as an upper bound if comfort is a priority. If the 99% load is what I would expect (23-26,000 BTU/hr if 2x4 R13 with tight low-E windows) the "ideal" furnace would have an output of no more than 1.4 x 26K= 36,300 BTU/hr, and not much more. That would mean something like a 40K two-stage 95% efficiency furnace (=38K out), half the size you're thinking of.

To get it right really means you have to do the math, but getting it right does a HUGE amount for comfort. For a primer on the effects of oversizing on comfort see Nate Adams' on-topic videos & blog bits and videos on the topic. (Nate's 99% outside design temp is about 5C cooler than yours at about -15C, but has a shorter heating season.)

What do you have for foundation insulation?

 

[Sponsor]

 

[Plumber69]

When I look at any charts online it tells me I want an 80. For the sq ft

 

[Dana]

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.