This is an important question, because if the airflow across the evaporator is reduced, due to any increased pressure drop caused by adding something in the air flow path, such as a TripleGuard air purifier, an extremely dirty air filter, or a denser air filter, performance can suffer, especially in areas where cooling and not dehumidification dominate. For more modern systems with ECM Constant Torque motors or variable air flow air handlers, the system automatically compensates for changes in pressure drop however, for older single-speed air handlers, this is a potential concern.
To accurately answer this question, the overall pressure drop in the entire ductwork of the system must be known, because it is the total pressure drop that effects the flow rate. However, a conservative worst-case estimate can be developed.
As noted in the installation instructions, when the TripleGuard is installed in the ductwork it should never occupy a major cross section of the ducts air flow path, but for a worst-case assumption, lets experimentally measure the effect on air flow rate and pressure drop when the TripleGuard is installed in a 3-ton system, and the TripleGuard blocks one-third of the air flow cross-section.
The air flow rate was determined by measuring the air velocity at 15 points within the cross-section of the duct both with and without the TripleGuard installed. As a means of comparison, two configurations were measured;
1) a high-performance filter without the TripleGuard installed and
2) a basic filter with the TripleGuard installed.
When comparing the two configurations the TripleGuard system had a slight increase in flow rate of 1.9%, meaning a slightly lower pressure drop, but the difference was negligible, because the measurement accuracy was 2%. Therefore, the pressure drop of adding a TripleGuard unit into the air flow ductwork is negligible and about the same as upgrading the filter in the system from a basic filer to an improved filter.
We used the high-performance low-performance filter comparison, as a means to demonstrate the negligible impact of the TripleGuard system on air flow rate and system performance. However, we recommend using both a high-performance air filter on the return air supply and a TripleGuard on the discharge of the air handler. See the installation instructions for further installation details.