Here’s a great detective story where the usual suspects were ruled out early! In my past IAQ work, I found that after the classroom training, reading as many case studies as I could get my hands on gave me the ability to think “outside the box” to identify the not so obvious. There are thousands and thousands of systems, chemicals, building science and building interactions that may create a myriad of outcomes, some not so desirable. The field experience will come but keep reading…something that many in the construction field do not do…those onboard here are the exception to the large general rule!!
Interesting. I know that my electronic air cleaner has an air sensing tube which senses air flow. I wouldn’t of thought the air cleaner would be charged with no air pressure on the sensing tube. My electronic air cleaner is a Honeywell. I wonder if other manufactures utilize a pressure sensing switch?
The airflow sensor controls the operation by automatically sensing air movement within the duct, which reduces power usage.
If the on/off sensor/switch is designed to sense a negative pressure as is created on the return side of an air handler, then it would still sense negative pressure if the unit were installed backwards since the whole return duct system up to the fan intake is negative relative to the rooms and supply side. With this type of filter there is very little pressure change from one side of the unit to the other unless the coarse filter gets plugged. This may have been an older unit without the energy saving technology.
From Honeywell:
[FONT=ArialNarrow-Bold][size=4]Position Cell Key
[size=2][FONT=Verdana]The electronic cell must always be installed so the ionizer section is on the upstream side. A factory-installed cell key on the bottom of the cabinet allows the cell to be inserted in only one direction. If the arrow molded into the plastic key points in the same direction as the airflow, the ionizer is always on the upstream side.
This will prevent the situation described in the article from occurring. So it seems the air flow sensor does not prevent it even with the newest, most up-to-date Honeywell units.