How many BTUs do I need?

[anonymous1977]

My 900 sq ft basement is heated by a one zone HVAC which is used for the above two levels which are 2500 sq ft. Ceiling height is 8feet for basement. If I wanted to install a gas stove in the basement what btu should I be looking for. 2.5 to 3 walls are insulated as they are exterior walls. The following Lopi product is only 21kbtu after using a 70 pct efficiency rating. However the ad says if can be used for 1500 sq ft. It does not seem to add up as my calculation shows about 40k btu needed.

Berkshire™ | Premium Cast Iron Stoves | Made in USA | Lopi Stoves®

FIREBACK OPTIONS INNOVATIONS GREENSMART™ REMOTE OPERATION VIDEO GREENSMART™ EMBER-FYRE® EFFICIENCY ×GreenSmart RemoteClose Select:SpecificationsInstallation DrawingsDimension DrawingDocumentsSelect: Heating Capacity: Up to 1,500 square feet Maximum BTU Input: 31,000 (NG/LP) BTU’s / Hour Steady...

www.lopistoves.com

 

[DAKSY]

Yeah, those stoves are tested in controlled, well insulated areas, &
the cited sq. ft. heating capabilities are a tad optimistic.
I agree with your calculations. 40K will do it. 36K should be able
to do it if you can find a unit that is rated for 75% efficiency.
If you can afford it, I would choose a higher BTU unit.
You can always turn it down. If you install a smaller unit &
at max burn rate it doesn't generate enough heat, you will be screwed.

 

[anonymous1977]

Isn't 75pct of 40k equal to 30k? You have indicated 36k. So is 30k sufricient? Is 36k a typo above? Also I assume you mean energguide efficiency rating.

 

[Fingerlakes Fireplace]

What the calculator is programmed to, is worst-case scenario.
So when you have zero degrees, and the wind is blowing at 30 miles an hour, it's going to take 40,000 BTUs, to maintain 70 degrees. The 99.99 percent rest of the time it's not going to take near that.