ARLINGTON, Va. - The Air Conditioning Contractors of America (ACCA) has released a new technical bulletin on “Temperature Differences in Residential Applications.”

According to ACCA’s Manual RS (Comfort, Air Quality, and Efficiency by Design), residential HVAC systems should control the temperature at the thermostat to within a few degrees of the set point during all but the most unusual weather conditions. The new technical bulletin explains why, on some days during certain hours, some rooms served by the most well-designed HVAC systems will not be able to remain at the recommended temperature difference from the central thermostat’s set point.

ACCA technical bulletins may be downloaded by members at For more information, contact ACCA’s Don Prather at

For more information on the association, visit

Publication date:09/21/2009