Honeywell FC40R filters - help?

ceburyJune 23, 2012

I've read the various posts on using the 4" MERV8 (or less) filters. I'm about to purchase them, but I have the cabinet that accepts 1" filters, but it does the metal tabs that can be bent/removed and hold a 4" filter.

However, Honeywell directions shows needing "7 inches total for a 4" filter". How important is having the extra 3 inches of space above the filter?

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It's hard to say how critial the space is above the filter. You may get a whistling sound as the air tries to rush through the constricted opening.

Have you considered using a 2 inch filter?

    Bookmark   June 24, 2012 at 12:27PM
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If whistling sound is the only downside (ie. not an extreme difference in strain on the blower) then I'll just order one of each size and see what works best. I assume the 2" will just need replacement more often.


    Bookmark   June 25, 2012 at 7:24PM
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UPDATE: I found another site explaining in more detail why I should avoid the 4/5" filter if I don't have the required 7" total space above the grill (really = 2 5/8" minimum above the filter before the flex duct starts).

The OP there has *exactly* my scenario with same filter box measurements and space available.

I guess I'll go with the 2" for now: I should've had them enlarge that box when I had them change out the ducting.

I was originally recommended to use the Honeywell F40CR 4" filters by ZippyHvac in the thread here . There appears widespread acceptance that these 4/5" filters are excellent, better than the 1" Filtretes, at least for their primary purpose: protection of the unit's coils, as they can collect a lot more particles w/out requiring often change-outs and do so with less increase of static pressure.

    Bookmark   June 29, 2012 at 1:36PM
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The 3M filtrete filters do a good job of filtering but are very restrictive. You are better off with a cheaper filter.

The 2 inch filter is still am improvement over the 1 inch. Even a good 1 inch filter is OK if you check and replace it on a regular basis.

    Bookmark   June 30, 2012 at 10:16AM
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