Depends on manufacturer recommendation; read the box or brochure for the furnaces you are considering.
I would say a 40,000 BTU furnace could big enough to heat a 400 SQ ft house, but where have you found a 400 SQ Ft house?
2500sq ft in northern climate
80000
The size of the furnace needed for a 2,200 sq ft house in New Jersey typically ranges between 70,000 to 90,000 BTUs, depending on various factors such as insulation, ceiling height, and local climate conditions. A Manual J calculation, which considers these factors, is recommended for a more accurate assessment. Additionally, consulting with a local HVAC professional can help ensure you select the right furnace size for optimal efficiency and comfort.
I strongly urge you to call a pro HVAC company and have them perform a manual J load calculation . However for years ,typically 75,000 to 100,000 btu furnaces in the south USA were the norm. Tom H. HVAC proffesional, New Orleans
For an 800 sq ft house in Ohio, a furnace with an output of about 40,000 to 60,000 BTUs is typically recommended, depending on factors such as insulation quality, ceiling height, and local climate. It's important to perform a heat load calculation to account for these variables for optimal efficiency. Consulting with a local HVAC professional can ensure you choose the right size for your specific needs.
rooms are 325 sq ft and suites are 625 sq ft
The size of the furnace needed for a 3,000 sq ft house typically depends on factors such as climate, insulation, and home layout. A general rule of thumb is to use about 30 to 60 BTUs (British Thermal Units) per square foot, which would mean a furnace with a capacity of approximately 90,000 to 180,000 BTUs. It's best to consult with an HVAC professional who can perform a detailed load calculation tailored to your specific home conditions for the most accurate recommendation.
No, despite that people will understand what you have written. But still 3 ft sq is not same as 3 sq ft.
21 ft * 10 ft = 210 sq ft = 19.51 sq metres.
A 60,000 BTU/hr. furnace will heat a 1400 square foot house. However, the average daily temperature, house insulation and other factors will have to be considered before making a final decision.