Home inspection findings by Frank Schulte-Ladbeck, Professional Real Estate Inspector TREC# 9073

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Creating a Tighter Building by Dampers on Vents

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To lower your electricity bill, you have to save energy. The biggest cost is air conditioning. How can we prevent loosing our conditioned air through vents which are open to the exterior.

I finally became bothered enough with the heat of summer coming through my range hood vent to take action. I have mentioned before that many vent that we have around the house are energy inefficient, because they are like open windows in our home. Think about it: your clothes dryer, kitchen range hood, and bathroom vents all go to the exterior. They push air out when the equipment is in operation, but they are open holes in our building envelope. I knew if they had a damper, there would be some form of barrier between exterior and interior. A damper alone is not the best. The damper prevents some heat transfer, but if we had weatherstripping, like on our doors, we would improve the efficiency of this barrier. I decided that I had to work towards a tighter building by closing off these holes.
    I had an idea of how the vent should be constructed. I knew others had complained about this fact, but I had never heard of such a vent being made. I headed to my local building center to see if I could find parts to make m vent. Usually when walking along an aisle, we examine products at eye level, but I was scanning up and down to see if there was a vent I could modify. To my surprise, I found vents on a top shelf that were described as LEED approved. Honestly, I have not seen them installed, and no one has mentioned them to me (I thought that I might see something like this at a green building resource center). They were a little more expensive than a normal vent, but not by much. I bought a vent for my range hood, which goes through my roof and for my clothes dryer. These vents have the damper with a weatherstripping insulation. All I would have to do is install them, or so I thought.
    The smaller vent for the wall is four inches in diameter, and it would work for a clothes dryer or bathroom vent. You may have a vent with a damper on it for these units, if you have a newer home, but they are not as energy efficient. These have plastic flaps that open to the exterior. These flaps do not seal with an insulating strip, and they are exposed to the exterior. My new vent has a cover over the damper. My vent also has a metal screen. I have been finding birds in these vents, so the screen and cover help prevent this intrusion. The cover also protects the damper from the weather. My problem was that a clothes dryer vent cannot have the screen on it. Your clothes dryer should have a filter for removing lint before it goes through the duct to the vent, but I always find some lint will get into this duct over time. The screen clogs with this lint, so there should be no screen for the clothes dryer. I had to remove the screen that came in my vent. My older vent had been clipped into the duct with a tab. This took a bit to remove the older vent, but it was not too hard. I then caulked the tube portion of the new vent, slipping it over my duct. I completed the job by caulking the exterior of the vent.
    The roof vent for the range hood was not too difficult to install either. I did see that this vent did not seem as tight as the smaller vent, so I added insulation (weatherstripping) to the interior where the damper sits. Removing the old vent was simple. With a crowbar, I pried the vent off of the roof sheathing. I had removed some shingles first. I discovered that squirrels, who had entered my and my neighbors attics this past winter, had moved the duct out of position. I replaced the duct into position. I slipped the tube from the new vent over the duct. I had caulked around the flat base of the vent to make a tight seal between vent and the roof. I nailed the vent into place under the shingles. In the attic, I did insulate around the duct, and I sealed the duct with that silver HVAC duct tape. This took me about a half hour. Quite a simple job, but I should say that my roof is easy to walk. Steeper pitched roofs might take longer.
    Are these vents helping to improve my energy efficiency?  I ask this, because many consumers are now concerned about payback. How much money will this save me? Is installing this vent worth the cost? I cannot give you a dollar figure. For the average American home, these vents that are open or partially open to the exterior are said to be the equivalent to leaving a window open all year long. I had not thought much about the clothes dryer, because my utility room is warmer than other areas of my home. In the kitchen, I have noticed that I do not feel the heat by the range hood that I felt previously. As I make my old home more air tight, my concern turns towards air quality. This may be the time to install an HRV, but my home is not that tight yet. I mention the air quality, because this should be something that you are considering as you make the building tighter.

« « Can Shutters Or Blinds Be Energy Efficient?| How Often Do I Need to Caulk Doors, Windows, and Wall Joints » »

© Frank Schulte-Ladbeck Professional Home Inspector Houston, Texas
Frank Theodor Schulte-Ladbeck
home inspector, TREC# 9073
Houston , Texas , 77063 United States
713.781.6090

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