Seattle Home Inspector's Blog

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The roofer and the heating contractor haven't been speaking to each other for 10 years.

     In the mid 70's, as homes became tighter and tighter to conserve energy, we started to devise mechanical means to bring fresh air into the home on a predictable basis to ensure air quality.  There are many ways to achieve this, and I am not going to discuss all of the different systems in detail.  The building codes eventually  "required" some means of changing the air at prescribed rates in all new construction and homes that were being substantially remodeled. 

     Sometimes the system is a stand-alone unit with its own ductwork----like a "Heat Recovery Unit." These systems are really cool because in the Winter they exchange the heat in the outgoing air into the cold incoming air (and just the opposite in the Summer). 

     Other times it is tied into a bathroom or laundry exhaust fan and there will be a timer located in the home that can be set so the fan turns on periodically. 

     Another method is for it to be tied into the forced air furnace system.  This type of system utilizes an air intake installed in the return air duct of the furnace with an automatic damper that is controlled by the furnace circuit board, timer and thermostat.  Here is what the automatic damper control might look like at the intake pipe in an attic.

Automatic damper 

     This is a very efficient way to bring fresh air into the home if you have a forced air system----although all of the different methods have their issues.  One of the advantages of this system is that the air in the home is filtered year round----not just in the winter when the furnace is operating.  And, because it utilizes the ductwork of the furnace heating system, fresh air is distributed to all the rooms in the home.

     Several times a year I find this particular type of system compromised because of lack of communication between the roofer and the heating contractor.  For the air intake to work properly it has to be able to bring in air when the automatic damper opens and the furnace blower kicks on to pull in air.  The roofer knows that the air-intake pipe needs a roof cap----so they install a typical roof vent cap----with a back draft damper in it----designed to move air out of the house not into it.  While the vent cap itself is most likely adequate----the damper must be removed for any air to move into the system.  A simple enough repair---but the damper in this cap has been installed this way for 10 years.

damper

     The flat plate-like flap of the damper can be seen behind the screen in the picture.

Charles Buell

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Comment balloon 7 commentsCharles Buell • August 19 2008 07:56AM
The roofer and the heating contractor haven't been speaking to each…
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In the mid 70's, as homes became tighter and tighter to conserve energy, we started to devise mechanical means to bring fresh air into the home on a predictable basis to ensure air quality. There are many ways to achieve this, and I am not… more
I "got religion" in the kitchen this morning!
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For those of you that have been hanging around my blog from the beginning of time, hopefully, have no clue when I am kidding and when I am not----and therefore you know that for me, doing the dishes is a " Religious Experience " … more
I think I need a cold shower!
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One of my favorite indulgences is nice long hot showers. I know they are not that good for you---supposedly----but I love them nonetheless. On a recent inspection I came across a different kind of hot shower. The light fixture in the shower… more
Are Townhouses an Olympic Sport yet?
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Three, and even Four story townhouses are popping out of the ground like Magic Mushrooms all over Seattle. They represent special problems for the Home Inspector: from roofs too high to get on, to having to undergo extensive Olympic Training… more
Is your Garbage Disposal "too-hot-to-handle? "
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One of those "nit-picky" (gotta love that word) things Home Inspectors routinely call out, is the electrical connection to the disposal. This connection is "messed-up" more than any other single defect that I can think of… more
How is your "Internal-Compensation-Engine? "
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In all areas of our lives today, there seems to be a huge lack of pride in workmanship----of doing the minimum---- just enough to get the pay check. Some people though----regardless of money----seem to go beyond the minimum. Why? … more
Are you "persistent? " (Is that a Crown? )
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What does it mean to be persistent? Mr. Webster defines persistence as: "continuing without change in function or structure. " Inspectors often have to be persistent as they move through the various components of a home--… more
At a "minimum" we have to do the minimum.
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Is your inspector a "code" inspector? Another way of wording this is: does your inspector inspect to "minimum" standards? Does your inspector inspect to the NACHI and/or ASHI Standards of… more
Big Brother----is watching!
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I think most inspectors are used to having someone look over their shoulder during the inspection. I know that in some areas the buyer isn't around until the end of the inspection, but in my area it is common for the buyer to be at the… more
I am not ready to be only in a drawer just yet!
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In the movie "The Rose" Bette Midler plays a Janis Joplin type character that just before she collapses on stage she asks, "Where is everybody going? " Sooner or later we all come face to face with our… more