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Leaks in HVAC Equipment Take a Toll on Efficiency

HVAC pros know that air handling equipment presents a real challenge for duct sealing because you have to allow for future access to the equipment for repairs and maintenance.

This is where good gasketing material and strategically placed DOWSIL silicone sealant work well together. Most cabinets leak a lot more than your typical hole due to the closeness to the blower. Base pans, electrical knockouts, refrigerant and drain line openings, and blower panels all top the list for top leakage points to address. The filter rack is another place that gets ignored and it is often left open to allow for access to the filter. Additionally, a lot of unfiltered and possibly unconditioned air is being pulled directly into the blower bypassing the filter.

Water source heat pumps are an obstacle too as the blower section sits directly on top of the compressor and control section. There are usually a lot of unintentional connections between the two areas, with dust on the lower panel being a telltale sign that this is occurring. Once again, strategically placed DOWSIL HVAC silicone sealant and gasketing can help to minimize this connection between the two compartments.

All aspects of the duct design process need to be given attention and verified before any proper sealing job can be considered worthwhile. To focus on only one variable as being more important than any of the others, is making a lot of assumptions. When proper duct sealing is combined with proper design and insulation, and airflow delivery that's been tested and verified, you have an HVAC system that will provide real comfort and efficiency.

The selection of the sealant you use to close leaks in your HVAC system can be just as important as understanding where and how to apply it. Some sealants are not specifically made for HVAC applications and will not adhere well or may not deal well with the fluctuations in temperature that must be taken into account. Some sealant brands are made with extending agents mixed in that save manufacturers money, but because the product is not 100% silicone and because of evaporation associated with extending agents the sealant may crack or become unstable over time. This is why you should always rely on DOWSIL (formerly Dow Corning) silicone HVAC sealants. DOWSIL is always 100% silicone with no extending agents added. To learn more about DOWSIL products go to

About the author

Master Distributor of Dow Corning Sealant Products and Distributor for Advanced Gloves and Dow Insulating Foams.


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