HVAC DUCT TESTING
Leaky ducts significantly increase energy needed for heating and cooling. Many field studies consisting of thousands of individual homes have shown time and again that existing residential air distribution systems can leak as much as 40% of the total supply air and can increase heating and cooling costs over 30%. Leaky supply ducts send expensive conditioned air (we just paid the energy company to heat or cool) into unintended unconditioned spaces such as attics and crawlspaces, and leaky return ducts draw outside dusty unconditioned moist air into the duct system.
Duct leakage measurements are used to diagnose duct leakage problems, estimate energy loss from duct leaks, and verify the quality of duct system installation. A Duct Blaster is a diagnostic tool that uses pressure testing to determine the amount and location of this duct leakage and quantify how leaky, or energy-inefficient, a duct system is.
How bad is duct leakage?
Let us consider how crucial a conservative estimate of 25% duct leakage is for a typical 4 ton AC system in a typical home. The standard blower setting on a typical HVAC system is set at 400 cfm (cubic feet per minute). This means that 400 cubic foot blocks of air are mechanically being forced throughout the ducts each minute the system is running for each ton of AC. If you have a 4 ton system that means this system is pushing 1,600 cubic foot blocks of air out of your vents each minute – if the system was air-tight However, since we are conservatively leaking (or mechanically pushing out) 25% of this air we are losing 1 ton of air that we just paid out energy company to heat or cool. So, for every minute our 4 ton system is running we are paying for 400 cubic feet per minute of heated or cooled air although this conditioned air is never reaching our living room, bed rooms, bathrooms, etc. A quarter of this air conditioned air is completely lost.
However, its gets worse than that! Since this 25% duct leakage is causing us to push 400cfm out of our home’s conditioned envelope every minute then we must also realize that 400 cubic feet of outside hot and humid summer air is being “sucked” into our home. Simply speaking, supply duct leaks suck in the same amount of outside air into our home that it pushes out each and every minute it is running.
But it get’s even worse than that! In our typical conservative example we are losing a tone (400 cfm) or air every minute. So, we are depressurizing our house by this same amount and sucking in 400 cfm. So, our 4 ton system is now truly operating with only a 3 ton capacity while running longer to cool and dehumidify 400 cubic feet per minute of 90 degree 90% relative humidity outside air. Its a vicious cycle that not only greatly increases our monthly energy bills but is also a major contributor of moisture problems leading to potential mold and mildew issues along with greatly decreased comfort.
Leaky ductwork can be the one largest source of energy in-efficiency in your home!