How Hidden Air Leaks Can Cause Big Trouble

How and Where to Look for Hidden Air Leaks in Your Home

Wasting energy and money at home is about 50% the homes fault and about 50% human fault. How we live in the home, our power lifestyle, has a great effect on the power bill at the end of the month.

It helps to have worked as a home builder when it comes to looking for hidden air leaks. It helps even more to have the use of a blower door, an instrument that measures whole house air leakage. A home builder with a blower door is very effective when it comes to looking for those air leaks that drain a wallet, month after month, without leaving a clue as to where all the money is going. Just a guess, but I bet you don't have a blower door and my guess is your not a home builder. In this article I will discuss one area of a home that spells trouble. If you have this area in your home, watch out, the air leak thief has been stealing dollars from you for years.

Recently, I visited a home built in 1996 to evaluate the home for high utility bills. The home is a two story with central gas heat and central air conditioning. The kids had recently left for work or college, so this couple had the home to themselves. No teenage daughters taking long showers. The blower door was set up and a test was run, the infiltration rate was nearly 3,200 (cfm) cubic feet per minute. For this home, the infiltration rate should be closer to 1,400 cfm. Heating ducts that leak air contribute to high air leakage readings during a blower door test. One thing for sure, the house is swiss cheese or the heating ducts are practically disconnected.

To save time and money during a homes construction, the heating contractor will often use framing structures as heating ducts. Instead of installing actual heating and return duct work, the contractor will pull a short cut and use a joist space or wall cavity, a soffit or furring chase to carry the air from or to the furnace.

Register in Side of Stairway Means Trouble If you live in a two story home and you have a heat register or return air grill that is installed in the wall framing of the stairway, you are possibly living with a major hidden air leak. Chances are, the heating contractor used the whole space under the stairway as a heating passage way. The problem gets more serious when the stairway cavity is open to the underfloor space and/or the attic.

In this home, I went under the floor so I could look at the insulation that was under the stairway. Sure enough, the insulation right under the stairway was almost black instead of being it's normal yellow self. Insulation will turn black when it is being used as an air filter. Black insulation occurs when air is passing through the insulation and the dust, dirt and lint in the air is being filtered out turning the normally yellow or pink insulation black. If you look at the insulation under your floor or in your attic and some of the insulation appears to be a lot darker than other parts, the dark area has air passing through it which deposits the dirt in the air on the insulation for all to see. Dark insulation means air leak.

The floor of this house was framed with tongue and groove 2 x 8 boards. There was no floor underlayment installed on the section under the stairway. When the furnace came on, the furnace fan sucked air from under the stairway. The return air grill, in the side of the stairway, supplied some air from the hallway, but the rest of the air feeding the furnace came from under the floor.

Problem:

1. The air under the floor is cold, so during the heating season, the furnace has to heat up cool air instead of the warmer air that is in the house. The furnace has to work harder.

2. The air under the floor is dirty, it plugs up furnace filters fast and contributes to poor indoor air quality. People with asthma can experience difficulty.

3. The air in the house does not get to circulate throughout the house and through the furnace filter as often.

4. When the furnace fan comes on, air from under the floor causes the air balance within the whole house heating system to pressurize. The house does not heat up as evenly or effectively.

5. The problem can go undetected for years.

The fix:

An insulation contractor was called that specializes in heating system duct sealing. The contractor performed a duct leakage test before and after repairs to the system. The duct leakage loss was reduced by 72%.

1. The return air register was removed from the wall of the stairway and the hole entering the stairway cavity was enlarged. This allowed a person to enter the area.

2. Half inch particle board was installed over the 2 x 8 tongue and groove. The edges and the joints of the particle board were caulked.

3. A round flexible heating duct was installed from one side of the stairway cavity, attaching to the furnace return air plenum on one side and attaching to the return air register on the other. Now when the furnace comes on, return air was drawn directly through the new heating duct from the hallway to the furnace.

4. The floor was sealed under the stairway so the dirty air from the crawl space could not get into the house.

Sure hope this was helpful, particularly to those that live in a two story home. For now, thanks for stopping by, hurry back, but I won't leave a light on for you...