What is a heat load calculation?
A heat load calculation (also known as a Manual J) is simply a mathematically based process for properly sizing an AC and Heating system. This means analyzing: the homes floor plan, the direction of all exterior doors and windows, the heat entering the home through the exterior walls, windows, the building's infiltration rate, the amount of heat that is generated by lighting, appliances and people to determine how many BTUs the HVAC system must generate to properly heat and cool a home. After the BTUs or heat load are known, then the TONS or tonnage of the system can be calculated. (i.e. 2 tons, 3 tons)
Designing a properly sized system can legally only be done by a licensed HVAC contractor.
Why do I need a heat load calculation?
Builders and owners need a licensed professional HVAC contractor capable of mathematically considering all pertinent data to properly size an HVAC system. If the equipment installed is too large the unit will short cycle and can cause issues such as poor indoor air quality, high humidity, high electrical bills, and a shortened life-span of the equipment. If the system is too small it will never be able to comfortably heat and cool the building. When contractors "estimate" the size of the equipment based on "years of experience" or an "educated guess," the margin for error increases significantly and leave builders and owners with little to no recourse to address correcting the expensive issues created by an improperly sized system.
Why does the IECC Inspector need a copy of my projects heat load calculation?
The IECC requires HVAC contractors/builders to provide code officials with a copy of the heat load calculation. As part of our inspection we verify that the size of the heat load provided is the same as the equipment installed at the job site. Additionally, we used the information included in the heat load to properly determine limits for the acceptable amount of duct leakage in each system.
A heat load calculation (also known as a Manual J) is simply a mathematically based process for properly sizing an AC and Heating system. This means analyzing: the homes floor plan, the direction of all exterior doors and windows, the heat entering the home through the exterior walls, windows, the building's infiltration rate, the amount of heat that is generated by lighting, appliances and people to determine how many BTUs the HVAC system must generate to properly heat and cool a home. After the BTUs or heat load are known, then the TONS or tonnage of the system can be calculated. (i.e. 2 tons, 3 tons)
Designing a properly sized system can legally only be done by a licensed HVAC contractor.
Why do I need a heat load calculation?
Builders and owners need a licensed professional HVAC contractor capable of mathematically considering all pertinent data to properly size an HVAC system. If the equipment installed is too large the unit will short cycle and can cause issues such as poor indoor air quality, high humidity, high electrical bills, and a shortened life-span of the equipment. If the system is too small it will never be able to comfortably heat and cool the building. When contractors "estimate" the size of the equipment based on "years of experience" or an "educated guess," the margin for error increases significantly and leave builders and owners with little to no recourse to address correcting the expensive issues created by an improperly sized system.
Why does the IECC Inspector need a copy of my projects heat load calculation?
The IECC requires HVAC contractors/builders to provide code officials with a copy of the heat load calculation. As part of our inspection we verify that the size of the heat load provided is the same as the equipment installed at the job site. Additionally, we used the information included in the heat load to properly determine limits for the acceptable amount of duct leakage in each system.