Load Calculations: Make Sure You Get The Right Size Heating and Air Conditioning System

Whether you are planning on upgrading your HVAC system, or installing a new, one you will need to make HVAC load calculations. Heat load is also known as heat gain and is simply the amount of heat generated. This number is calculated in British Thermal Units (BTUs) or Kilowatts (Kw). If you want to convert from BTUs to Kw, 1 kilowatt is equal to 3,412 BTUs.

There are several factors to consider when you are calculating the heat load of your home. Those factors are as follows.

  • The square footage of the room.
  • The average number of people who are in a  room at any one time.
  • Windows. The size, position and whether they use blinds.
  • The heat generated by the equipment in the room (electronic equipment) and by the lighting.

Step One:

These HVAC load calculations are fairly simple. The BTU of the room is equal to the length times the width times 337.

Step Two:

Windows are measured by the direction they face.

  • North facing windows use length times width times 165.
  • South facing windows use length times width times 870.
  • If you have no blinds or curtains on the windows you will have to multiply the result of the above calculations by 1.5.
  • The three totals are added together to get the BTU requirements.

Step Three:

Next measure the BTU requirements for the average number of people in the room at one time and the heat load of the equipment and lighting.

  • Each person in a room will add about 400 BTU to the requirements. So if the average number of people in the room is 5 you will need 2000 more BTUs.
  • Equipment is measured by multiplying the total wattage by 3.5.
  • Lighting is measured by multiplying the wattage of the lighting by 4.25.

Now you can make the right HVAC load calculations by adding the totals together. This will tell you the amount of BTUs you will need to cool the area.  Contact us and we’ll do a complete evaluation of your heating and cooling needs, to ensure that you get the right size system for you.

Home Comfort services the Mishawaka/South Bend areas of Indiana.

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