I have a Honeywell electronic furnace filter on my furnace. The power panel failed and the unit is very expensive to replace. However, I can install pleated air filters in place of the original electronic cells.
The filter size is 20 X 25 X 4 inches thick. As a temporary measure, I have installed 3-1 inch thick MERV 8 air filters in parallel into the filter opening. How does the MERV rating change when the filters are placed in parallel? Is what I have done a good solution? If not, what would you recommend that I do?
I would remove two of those 1 inch pleated air filters ASAP. Installing filters in this way has a very negative effect on air flow and reduces equipment efficiency greatly. Take a look at your air handler to see if there is a place to install a 1″ filter. Most air handlers come equipped with this filter rack.
Take a look at the pictures on this page “where is my furnace filter” if you are not sure where to look. If you can’t find a place to install a 1″ filter, you can get a 20 X25 X4 MERV 12 filter at NordicPure for a very reasonable price.