3 Types of Heating and Cooling Loads to Know About
August 27, 2015
Heating and cooling loads are the measurements use to determine how much heating and air conditioning your home requires to reach a set temperature. This differs from the "capacity," or the heating or cooling output of the HVAC equipment. The load calculations are further broken down into design, partial and extreme loads, which are calculated to size HVAC equipment correctly.HVAC systems sized too small will strain to meet the building's load, while a system that's too large will short cycle, or turn on too frequently, and run inefficiently.
Design conditions include outdoor conditions to which the home will be subjected, as well as indoor conditions that have an impact on equipment operation. Design conditions for HVAC equipment in our region are found in industry software called Manual J, which helps consultants determine heating and cooling loads. Consultants take into account the R-value of insulation, number of people in the home, design and orientation of the home, square footage, windows and other factors. These data help determine the design load, or the cooling and heating needs of the home at a certain outdoor temperature to achieve a desired indoor temperature.
A/C or furnace loads are usually less than the design load for the major part of the year. This means the HVAC system may be operating to satisfy what's known as a partial load. In this case, the system may be short cycling, even though it is sized correctly. Short cycling can result in inadequate dehumidification and overworking of parts.
Another factor to be considered when determining the HVAC system size is extreme load, or the outdoor temperature extremes the equipment will be affected by. However, systems aren't designed to meet these extremes. If they were, they would probably be oversized. Generally, the A/C or furnace will be designed to meet temperatures just 15 to 20 percent beyond design conditions.
For more on heating and cooling loads, contact Lozier Heating and Cooling of Des Moines. We've served central Iowa's heating and cooling needs with outstanding service and equipment installations.
Our goal is to help educate our customers in the greater Des Moines, Iowa area about energy and home comfort issues (specific to HVAC systems).
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