| 主权项 |
1. A method for measuring HVAC efficiency for use with an HVAC system which includes at least one fan for moving air through the HVAC system and one or more heat transfer elements that act to effect heat transfer to or from the air within the system, the one or more heat transfer elements including a heat transfer element to be measured, wherein the direction which the fan forces the air through a duct within the HVAC system is considered downstream, the method comprising the steps of:
(1) turning off all elements and running the fan until the system reaches a steady state condition; (2) measuring the enthalpy of the air at a predetermined point within the HVAC system, the predetermined point being that point in an HVAC system duct, downstream from all of the heat transfer elements, that is closest to the heat transfer element to be measured where a cross-sectional temperature profile of the air within the duct varies by less than 0.5 degrees Fahrenheit; (3) turning on the heat transfer element to be measured and running the HVAC system until the HVAC system reaches steady state; (4) measuring the heat transfer rate introduced to the HVAC system by the heat transfer element to be measured; (5) after step (3), measuring the enthalpy of the air within the HVAC system at the predetermined point; and (6) using the measured heat transfer rate of the heat transfer element to be measured and the change in enthalpy of the system air to calculate the air flow within the HVAC system. |
