Furnace size for a 1950s Toronto Bungalow

fieldhousehandyman wrote: ↑ I have a 3000 square foot (on first and second floor) double brick Victorian home, uninsulated and installed an 85k BTU furnace which has no issue at all keeping the place heated.

I did the design calculation myself from a technical sheet posted on the CMHC website (no longer available) Actual design requirements were 57K BTU if I recall, I can send you the link to my blog which has the actual calculation.

40k btu is more than sufficient for your house, and is likely the smallest available furnace anyway.

1cat2dogs wrote: ↑ Question for the experts:

Just got quoted for a 40000 BTUH Goodman 96% EFF 2 STG Gas furnace on a 1200 SF bungalow with 900 SF of finished basement.

That seems rather small to me? What says the experts?

1950s brick/brick with 20yr old windows and original insulation rental property.

TIA for any comments.

1cat2dogs wrote: ↑ Question for the experts:

Just got quoted for a 40000 BTUH Goodman 96% EFF 2 STG Gas furnace on a 1200 SF bungalow with 900 SF of finished basement.

That seems rather small to me? What says the experts?

1950s brick/brick with 20yr old windows and original insulation rental property.

TIA for any comments.

sickcars wrote: ↑ We got a 40,000btu Goodman 2 stage furnace down from a 80,000btu installed by @newlyborn and its been great. Home is 1,200sq brick, semi no insulation home from around 1910.

40k seems about right for you in a bungalow. What current size & type of furnace do you have now?

newlyborn wrote: ↑ I concur @fieldhousehandyman . We recently installed 60K in 3000 sq ft home AFTER homeowner got his heat loss calculations done. Even though house was 20+ years old, it was very well insulated with new windows and almost no leaks from outside.
When sizing is done without heat loss calculations, one must consider
1. House size
2. Type of house ..Detached, semi or townhome ( how many walls are exposed )
3. Insulation
4 Window size and conditions
5. Exposure to sunlight

WikkiWikki wrote: ↑ Alot of this has to do with the Climate Zone you are in to I imagine

The BTU usage recommended for each house size is not a single number but rather a broad range. Square footage is not the only factor.

Climate zone
Edmonton is in Climate Zone 5. (Of course it’s the coldest.) Recommended BTUs are between 40 to 50 per square foot.
Quality of Insulation
How well is your home insulated? New homes tend to be around 50 BTUs and the older ones closer to 60 BTUs. To get the total BTUs required, you simply multiply the total square footage by the recommended BTU per square foot.
Other factors
Window thickness (single/double/triple glazed), ceiling height, number of people living in the home and the temperature they find comfortable.

The one you replaced was only using 20 BTU per sq. foot as the calculation. While I understand sq. footage is only one factor, the climate zone you live in has to be factored in as well doesnt it?

The same house in Ontario picked up and moved to Alberta or Saskatchewan, would not have the same size furnace. Or am I completly wrong on that?

fieldhousehandyman wrote: ↑ A furnace sizing calculation which uses actual fuel consumption, and local historical weather data, like in the page from my blog I linked, eliminates all conjecture, guesswork, and other factors that play a role in furnace sizing, rendering all that information moot.

The calculation uses actual consumption over three months, and three months of weather data, and does not care what size furnace you have, how many windows, how many floors, doors, how much square footage, or where the house happens to be located, as all that information is unnecessary

WikkiWikki wrote: ↑ Alot of this has to do with the Climate Zone you are in to I imagine

The BTU usage recommended for each house size is not a single number but rather a broad range. Square footage is not the only factor.

Climate zone
Edmonton is in Climate Zone 5. (Of course it’s the coldest.) Recommended BTUs are between 40 to 50 per square foot.
Quality of Insulation
How well is your home insulated? New homes tend to be around 50 BTUs and the older ones closer to 60 BTUs. To get the total BTUs required, you simply multiply the total square footage by the recommended BTU per square foot.
Other factors
Window thickness (single/double/triple glazed), ceiling height, number of people living in the home and the temperature they find comfortable.

The one you replaced was only using 20 BTU per sq. foot as the calculation. While I understand sq. footage is only one factor, the climate zone you live in has to be factored in as well doesnt it?

The same house in Ontario picked up and moved to Alberta or Saskatchewan, would not have the same size furnace. Or am I completly wrong on that?

fieldhousehandyman wrote: ↑ Here is the link to my calculation on my blog

Furnace Sizing Calculation

Fieldhousehandyman's Blog wrote:A Sample Aggregate Count Of The Number Of People With Nothing Better To Do!
63689

Quentin5 wrote: ↑ Aah! I've been rickrolled into visiting your website!

EugW wrote: ↑ No. That is terrible advice.

That 50-60 BTU per sf rule of thumb would oversize the furnace the vast majority of time, unless you live in a very leaky and very poorly insulated century home or something.

In fact, even for zone 5, for a modern home with decent insulation and proper duct work, that rule of thumb would often oversize the furnace by 100-200%.

WikkiWikki wrote: ↑ But this is the problem. Every site has contradicting information. I looked at info for a few hours and last night. Some were as low as 20 Btu per sq foot all the way up to 60. All of these were HVAC sites as well. Canadian sites and US sites

Even on RFD there is contradicting info on sizing. And even with in person HVAC techs.

So the question is, who is actually right?

WikkiWikki wrote: ↑ But this is the problem. Every site has contradicting information. I looked at info for a few hours and last night. Some were as low as 20 Btu per sq foot all the way up to 60. All of these were HVAC sites as well. Canadian sites and US sites

Even on RFD there is contradicting info on sizing. And even with in person HVAC techs.

So the question is, who is actually right?

fieldhousehandyman wrote: ↑ None of them are right, it is nothing more than guesswork... The only thing that works well is a furnace sizing calculator that uses two sets of data, actual energy consumption for the home you are sizing for, and local weather information (degree days)

stop wasting your time about who is right or wrong, an equation that uses ONLY fuel consumption and degree day data makes all of that other garbage completely irrelevant