Question about Envirosept Furnace Filter Panels and How to Choose the Correct Size.
Q: "I have bad allergies. I have a 5 ton Carrier HVAC system. I am currently using the disposable paper filters with the cardboard surrround. When I push the filter into the 1 inch furnace slot, the spring at the back causes the filter to buckle. My furnace slot is 21.5 x 23.25. Do you have an Envirosept to fit this size opening? Is this more effective than a paper filter? How does it work? Thanks. Bill"
Answer: In the furnace industry, furnace filter sizes are actually rounded up to the next whole number. (Thank you for your question because this was not a fact that was active in my mind!) I phoned the manufacturer and learned this and also that a 2 x 4 is actually 1.75 inches by 3.5 inches! Actually, in the first paragraph of every Envirosept Furnace Panel, Safe Home does give this information!
To determine the actual size of what you need, imagine a picture frame. You would measure that edge to edge across the top and the same up the side. That is how you measure a furnace filter. Then you pick the next larger furnace filter or furnace panel. Or you can remove the disposable furnace filter and measure it the same way.
In your situation, you would need the EnviroSept 22x23 Furnace Filter Panel,14 Filter Pads. This panel actually measures 21.5 inches by 23.25 inches, the measurements you gave me on the phone. This Envirosept includes 14 filter pads, two of which are in the furnace filter panel when it is delivered. So this filter size is rounded up if it is .5 inches for the 22 part and rounded down for the 23 part since your filter is 23.25 inches.
To get the most from your Envirosept, you need to run the fan continuously and change the filter pads regularly. This can mean every 3 to 4 weeks or even longer. We recommend that you check the panel after the first two weeks. Your choice then is to take the dirty primary filter and throw it out and use the secondary filter in the primary or first slot or replace both filter pads. Remember you do need an electrical outlet for this unit.
Thanks for your questions.