Improving the Efficiency of Your Heating System


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Duct Losses Hurt Forced Air Heating System Performance, Oikos Green Building Source



Good article describing findings on forced air duct systems showing that a 30% loss in heating and cooling efficiency due to duct leaks and poor duct insulation is typical
Five bucks for a can of duct mastic and a half a days work could save you a lot on heating fuel and green house gas emissions.
See the sealing guides in this section or the Harley book for how to do the sealing.
More on Duct Sealing

AeroSEAL Duct Sealing System


This is a process for sealing ducts that works for the inside.  It will reach areas of the duct system that are built into walls or otherwise inaccessible. 

Here is a comment from the Greenbuilding Discussion Group ( ):
"I have sealed many duct systems by removing the grills/registers and using UL-181 duct mastic on all the joints I can reach. I then seal everything accessible at the furnace that is accessible. Most of the time I get to below 6% (California code for new ducts) without touching anything else. If I don't get below 6% then I go to the duct runs that are accessible. Only very large duct systems, and those with ducts buried I can't get below 6%, but I'm usually close.
I know the person who developed Aroseal, you have to do some manual work anyway with larger holes (grills/registers ?) and you will only get as tight as the operator has time to sit around pumping more sealant into the ducts. It is a great process for inaccessible duct systems that can't be sealed otherwise."