How to determine the best furnace size for your Minneapolis home

Furnace size - Twin City Heating, Air & Electric

You may be  wondering why our technician needs to come to your house to do an estimate on a new furnace and air conditioning system. This is not a sales technique for Twin City Heating and Air – we put your needs ahead of any transaction we do.  It’s much more technical than that.

We get to know your home

Each home is different. When our technician comes to your home, he or she will look at your current furnace, assess the efficiency of both your home and your current furnace or air conditioner and then offer you options based on the assessment.  If you get a system that is too small, it won’t be efficient and operate properly. If your system is too big, you would be wasting money by paying for something you don’t need.

Determining your best furnace size

A furnace connects to ducts that push air through interior vents.

Residential gas furnaces are available in a variety of sizes and are measured in British thermal units, or BTUs, per hour. A BTU is the amount of energy that’s required to cool or heat 1 pound of water by 1 degree Fahrenheit. You can use very basic calculations to get a rough estimate of furnace size, but it’s important to have an HVAC professional perform detailed calculations to determine an appropriate furnace size and type for your home and heating goals.

Minneapolis Heating Company

Determining your furnace size

We have a strategic process for determining your furnace size here at Twin City Heating and Air and confirmed several key tips for homeowners through a furnace size article at SF Gate. When determining your best furnace size, it’s always best to start with these easy steps.

Calculate your square footage

Start with calculating the square footage in your home’s living space.  You won’t need to  include measurements for rooms that don’t have the ductwork or vents for heat or air conditioning. Measure your ceiling height for reference..

Consider your climate

Consider the climate you live in, including high and low temperatures, and the length of each season.. In general, the colder your climate, the bigger your furnace.

Consult a furnace manufacturer

Consult a furnace manufacturer or installer and and learn the recommendation based on their charts to determine the best furnace size for your home

Consult an HVAC expert

Consult an HVAC expert for further analysis and calculations before selecting a furnace. Manufacturer recommendation charts give you a simple starting point, but there are other important criteria to consider, such as the age  of your home, construction, how much insulation you have in your walls and attic, and the quality of your windows, doors and seals.


Twin City Heating and Air offers free evaluations and estimates for replacing your furnace, boiler or air conditioner.  Call 763-757-4678 to make your appointment or complete our contact form and one of our office staff will contact you to schedule.