System Design Calculators

This page provide the home owner with some of the details necessary to determine the capacity of equipment. Your can just call us and we'll take care of the design work, but for those who want to be more involved in the design work we offer this information.

Residential Heating and Cooling Calculator
The following information will allow you to assess a rough estimate of equipment and materials necessary to add or replace heating and cooling equipment in your home. To complete the following work sheet you'll need the rough dimensions of the finished areas of your home.

Limitations
To properly configure the heating and cooling equipment for you home an extensive list of details about the construction of your home must be collected. The size and orientation of windows, the thickness of insulation in walls and ceiling, number of fireplaces, etc., are all factors we use when making a professional recommendation of the equipment to use in your house.

For the purposes of the calculations you're about to make here, we will use average values for these details. Therefore the equipment sizes and costs determined here will possibly be different from those which our trained salespeople will calculate for you. The data provided here is intended for use in homes located in New England where the average winter minimum low temperature is 10º F. and the average summer maximum high temperature is 90ºF.

BTUs
Heating and cooling equipment is designed and manufactured to deliver (heat) or remove (cool) a specific quantity of heat from the house. The most common unit of measure of heat is the British Thermal Unit (BTU).

For the purpose of the following calculations we will base the amount of heat your house needs to be 40 BTUs per hour for each square foot of living space in your home. For cooling, the calculations are based on 20 BTUs per hour for each square foot of the living areas of the house.

For example:
Your home is 2 stories above ground with a basement that you use for storage. The house measures 24 feet by 36 feet on the first floor and 20 feet by 36 feet on the second floor. The basement is used only for storage.

First floor: 24 ft. x 36 ft. = 864 sq. ft.
Second floor: 20 ft. x 36 ft. = 720 sq. ft.
Total area to heat: 864 sq. ft. + 720 sq. ft. = 1,584 sq. ft.

Using the average of 40 BTUs per hour per square foot, we estimate that the house will need a heating unit capable of delivering 1,584 sq. ft. x 40 BTU hour/sq. ft. = 63,360 BTU every hour.

Using the average of 20 BTUs per hour per square foot, we estimate that the house will need a cooling unit capable of removing 1,584 sq. ft. x 20 BTU hour/sq. ft. = 31,680 BTU every hour.

Humidification
Humidifiers add moisture to the environment you live and work in. Humidifiers are needed when the humidity level drops below the comfort level, typically November through March in the New England area. The amount of humidity you can add to your home or office is based on your personal comfort and the ability of the outside walls to hold the moisture in. Generally speaking, the walls and windows of the home are the limiting factor in the design.

Humidifiers are generally rated in either gallons per day or pounds per hour. One gallon equals 8.32 pounds. The smaller humidifiers use the gallons per day rating, while the larger units are rated in pounds per day.

Although every environment needs to be evaluated individually, we have found a general guideline that works for many homes and offices. We generally recommend 0.004 gallons per square foot of space to be conditioned. Based on this general rule the following table of capacities may be used to estimate the equipment capacity:

Area of space	Pounds per hour	Gallons per day
1,500	6	17
2,500	10	29
3,500	14	40
5,000	20	58
7,500	30	87

Dehumidification
Dehumidifiers are used when moisture levels are high. Basements and enclosed pool spaces are two areas we regularly need to dehumidify.

Note: Moisture removal is an automatic function of central cooling systems. When the space needs to be both cooled and dehumidified, we design a central cooling system to meet the need.

Dehumidifiers are needed when the humidity level rises above the comfort level, typically May through September in your basement and year round in open water areas like pools. The amount of moisture you need to remove from the space is based on your personal comfort and the ability of the outside walls to hold the moisture out.

Humidifiers are rated in their ability to remove moisture in pints per day.

Though every environment needs to be evaluated individually, we have found the following guideline provided by the Association of Home Appliance Manufacturers works for many spaces. This table shows capacities in pints per day based on three environments:

Area of space	Moderately Damp	Very Damp	Wet Spaces
500	10	12	14
1,000	14	17	20
1,500	18	22	26
2,000	22	27	32
2,500	26	32	38
3,000	30	37	44