The Inside Outside Guys: Seal the Duct System

By Ken Calverley and Chuck Breidenstein

DETROIT, November 3, 2022 ~ Everyone who has ever lived in a home in the Midwest is aware of it.

It might be the feel of cold air moving through an exterior wall receptacle or near a window. It might be the always- cold-in-winter room that is also always hot in summer.

It” is air leakage in and around the home. We spend thousands of dollars in equipment and fuel to keep our homes comfortable only to fall prey to these insidious leaks everywhere.

In the home, we rate this unwanted exchange of conditioned air from inside with unconditioned air from outside in terms of air changes per hour, ACH.

This is a measure of how often the conditioned air in the home is exchanged for outside air due to gaps and cracks throughout the envelope (walls, floors and ceilings), that surround the living space.

Older homes may have up to 10 ACH, which means you are exhausting all that expensive, conditioned air up to 10 times every hour of every day and re-conditioning the raw air from outside that leaked in.


The Inside Outside Guys ~ November 6, 2022

Air leaks in the thermal envelope of new homes have been addressed by recent codes that require the homes to be air sealed and tested. A maximum of 4 ACH is allowed in a newly constructed home for it to be occupied.

In theory, we would like the envelope to be perfectly sealed while we control the intake of fresh air and the exhaust of stale air through such devices as ERVs, energy recovery ventilators, which can allow measured air exchanges while capturing the warmth and humidity of conditioned air prior to it being pumped out of the house with fans.

But, what about the air leaks inside the home? For decades the industry has debated the veracity of this issue. Is it really a problem if conditioned air leaks out of duct work at random points throughout the system?

If this leaking air is still in the home, aren’t we benefiting from it?

The answer is a weak “yes” with a caveat or two attached. What if heated and humidified air is leaking from the ductwork in a floor framing cavity and that humidity contributes to the growth of mold in that hidden space? Yes, the warmth is still in the house, but the mold will eventually create serious issues.

And, what about the reality that the conditioned air meant to arrive in that bedroom at the far end of the house will never get there now. It all leaked out before it got to where we wanted it to go.

Steve Dickinson, an owner at Amistee Air Duct Cleaning and Insulation in Novi, has a great analogy for this dynamic. Imagine turning on the water to a hose with the intention of watering a newly planted tree.

The old hose has so many leaks in it that almost no water gets to the end of the hose, where you want it to be. The same thing is happening in your leaky ductwork.

Additionally, leaks affecting 20% of airflow can cause a 50% loss in efficiency in the HVAC system.

So, your leaky ducts are not only costing you dollars in lost efficiency, but parts of the house are never comfortable to be in.

You should also know that if air can leak out of a system, it can also leak into the system carrying allergens, mold spores and other contaminants.

Amistee discovered a solution to this issue a few years ago when they began using Aeroseal to plug up all those duct leaks.

Their trained technicians can pressurize the duct system and measure how much conditioned air is getting to each room in the house. A typical duct system will leak 30% to 50% of the air sent through it before it is sealed.

Amistee technicians have worked in homes where they have recorded duct leakage equal to a 3-foot-by-3-foot opening.

The beauty of this nontoxic product is that, after treatment, those rooms that were impossible to condition are now as comfortable as the rest of the home.

Now that we have all battened down the hatches in preparation for the onslaught of winter, wouldn’t it be nice to know our home will be efficient, comfortable and healthy?

It can be if you work with the right professionals like those you’ll find at

For housing advice and more, listen to “The Inside Outside Guys” every Saturday and Sunday on  760 WJR, from 10 a.m. to noon, or contact us at