Question:
Which pleated furnace filter is better from the same company. 7 pleat or 11 pleat?
I would say 11 pleats per inch of filter is probably better, because more pleats per inch means there is more material in the filter overall. This results in a filter with greater dust loading capacity than a filter using the same material with fewer pleats per inch and there will be less impact on air flow.
Quality manufacturers aim for as little impact on air flow as possible when designing their filters. As the efficiency of the filter material increases so does air flow restriction. One method of compensating for this is to have more pleats per inch of filter.
More pleats per inch also distributes the dust collected by the air filter over a larger area and therefore can remain in the system longer before it must to be changed.
Best,
P.S. If you have used hepa air filters you probably noticed they had many more pleats per inch than other filters that utilize the pleated design.