Have you ever experienced uncomfortable conditions within your house between floors or from room to room?
Very often this situation has nothing to do with the mechanical equipment, rather “system design”.
Brentwood is located in Williamson County, which has some of the most influential housing developments in the State of Tennessee. These very complex homes require complex HVAC system design!
The problem does not always lie with the HVAC mechanical contractor but can be traced all the way back to the architect!
An understanding of “Building Science” is crucial in the evaluation of this issue because this encompasses is a wide range of building specialists. One such source of information may be obtainable through a residential home inspector who evaluates the entire building rather than small sections of it.
Very often I find bonus rooms (which are located over a garage) with the inability to heat and cool the space adequately. This is often associated with the fact that all of the floor, ceiling and walls are adjacent to unconditioned spaces, which increase the heating/cooling load on the HVAC equipment.
Another source of the problem has to do with construction of the building.
Improperly sealed HVAC return air ducts will often cause air to be drawn down into the walls of the finished space from the attic. The thermostat is most often (and should be) located directly above the return air grill (see the small square in the picture below). The return air all is in a negative pressure and will draw unconditioned air from within the wall from any direction if not properly design.
In this case, hot air is drawn down from a 150°F attic causing the wall and thermostat to detect temperatures greater than the actual space within the house. This causes the air conditioner to run long beyond the setpoint temperature of the thermostat. These conditions are quite evident with infrared thermal imaging.
Another major source of inefficiency is HVAC supply air leakage.
Almost 90% of supply air registers leak conditioned air into the unconditioned attic or crawlspace. This loss can account for 20 - 60% increase in your utility bill.The cubic feet per minute (CFM) which is being discharged into the unconditioned space is a huge efficiency loss. Not only is the air which has been conditioned by the HVAC equipment being discharged to the outdoors, the same quantity of CFM must be drawn into the conditions space of the house around window, door and wall openings!
An example of this condition is hot air being back drafted through a bathroom ventilator fan. This condition also frequently exists at most recessed lighting installed in the home.
So as you can see, this is a double whammy!
You not only lose conditioned air, but you must condition the effect of the initial loss.
I do not intend to place the burden of this evaluation upon a home inspector as it is most often outside the scope of home inspectors. However, it is essential that you utilize a home inspector that understands these principles and can recommend and evaluate projected repairs and evaluate actual performance of these repairs if you have an adverse condition in your home and are employing a home inspector to evaluate the condition.
All home inspectors bring specific expertise from the building industry to bear during their home inspections. They can be relied upon to refer you to the proper course of action.
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