Upstream InstallationUpstream: This refers to installing the air filter monitor on the cold-air return duct before the filter and blower.
Downstream InstallationWhen you install the air filter monitor downstream, you place it on the cold-air return duct after the filter, and before the blower. This is the ideal location for installing the FILTERSCAN.
Differentially across the filterIn this case, the air filter monitor is installed either before or after the filter and using the optional Tubing Kit. Set the slide switch to the Downstream position for differential mounting.
