The following diagnostic tests and calculations are part of the HERS Rating Process:
System Temperature Change
This measures the wet bulb temperature of air entering your system at the return grill and compares it to the temperature of the
air delivered to the supply registers in your ceiling - and shows the actual temperature change your system is delivering
This measures the volume of air coming from the A/C ceiling grills in each room of your house.
The purpose of an air conditioning/heating system is to remove/add heat and deliver this
conditioned air to your rooms. The BTU of heat your system is removing/delivering is simply a
function of how much your system changes the temperature and how much of this conditioned air
is delivered. [12,000 BTU is 1 "ton"] We calculate your system's Delivered BTU with the data
collected (above) on delivered air volume and system temperature change.
This is a comparison of how many BTU your system is delivering to how many it is rated to deliver.
The national average is 57%. The goal should be 90% or higher.
Two further tests determine the quantity of conditioned air leaking from your distribution system and the temperature gain or loss in this system. These measurements reveal the adequacy of your duct system.
Duct Leakage Test
This test measures the volume of air, in cubic feet per minute, leaking
from the distribution system.
Equipment Temperature Change
This measures how much heat is being taken out of the air as it passes
through the air conditioning equipment. Comparing this temperature
change to the temperature change in air entering and leaving the duct
system reveals how much heat is being lost or gained in the duct system.
Without the diagnostic testing described above, it is not possible to measure how well your system is performing - or where to do remedial work to bring its efficiency up. Remedial work often improves your system more than buying a new system would - and it is far cheaper.
If your HVAC system's performance is woefully inadequare - and it is new enough to warrant repair rather than replacement - we will connect you to the few HVAC contractors able to diagnose where in your system repairs can be made to dramatically improve its performance and reduce energy consumption. These A/C contractors will perform the following diagnostic tests to pinpoint trouble spots that can be easily corrected.
External Static Pressure
This is the pressure in your A/C system against which your fan must push. If it is higher than what
the fan is designed for, the volume of air distributed to your rooms (measured in cubic feet per
minute, or CFM) can decrease dramatically.
Filter Pressure Drop
This test measures how much your air filter is restricting air flow and reveals if you need a better
approach to filtration or a larger area of air return grill.
Evaporator Coil Pressure Drop
This test measures the difference in pressure on either side of the evaporator coil. It shows how
much the coil is restricting air flow and whether it needs cleaning.
The HERS process also includes...
Managing Installation (MORE INFO)
Verifying Performance (MORE INFO)