What is Makeup Air?? Makeup or compensating air is simply outside air that is introduced into the building to replace air that is exhausted from the building through ventilation or combustion processes.

Are direct fired HTHV heaters really 92% efficient?

That depends. If the direct fired heater is being used to replace a specific amount of air that is being exhausted from the building, it is generally considered to be 92% efficient. However, if Direct Fired HTHV space heaters are being used for space heating purposes in a well insulated warehouse, the systematic efficiency will likely be well below 80% in colder climates. For more information about how low that efficiency can go, a Purdue University research study sheds new light and provides answers to the real efficiency of HTHV space heaters.

Executive Project Summary of SYSTEMATIC ENERGY EFFICIENCY STUDY FOR DIRECT AND INDIRECT FIRED HEATERS By: Bin Wang