Forced Air Furnace Btu Calculator

This hvac calculator is the closest estimate to the actual manual j calculation done by hvac pros.

Forced air furnace btu calculator.

Then to calculate the output on a given gas furnace multiply it s efficiency rating by it s listed input rating to determine the actual btu output of heat. A more efficient furnace will output more btus of heat than a less efficient furnace with the same btu rating. Variables let s talk about all of the variables that come into play when selecting a new air conditioner system or furnace. A heating degree day calculation using the month of july as a factor is a more precise way of estimating furnace size.

Furnaces are rated on their btus of energy consumption not their btus of energy output. For example if a furnace has a listed input rating of 90 000 btu s and an efficiency rating of 80 it will produce 90 000 btu input x 80 efficiency 72 000 btu actual output. The size of a furnace is based on how much heat it can produce in an hour as measured in btus or british thermal units. The heat load estimate is based on your climate region total square footage number of rooms or zones you want ceiling height insulation type number of windows and doors.

As for air conditioning in homes even though acs are meant to cool homes btus on the technical label refer to how much heat the air conditioner can remove. In the example above using an 80 efficient furnace the 2000 square foot home above would require a 100 000 btu input furnace which will produce the necessary 80 000 btu s output of heat. The higher the btu rating of an appliance the greater the heating capacity. This hvac load calculator quickly estimates the size of your heating and cooling system in btu s.

If that same furnace has an efficiency of 95 the furnace will produce 95 000 btu of heat. Different furnaces of the same input btu have different efficiencies measured in percentages. For example if a furnace is rated at 100 000 btus and is 80 efficient then the heat output will be 80 000 btus 100 000 x 8. That means the furnace will produce 80 000 btu of heat.

For example a furnace with an input btu can have an efficiency of 80. To avoid these headaches follow our detailed guide on how to accurately calculate the furnace size that is most suitable for your home.