Are FC40Rxxxx Filters Worth It and When too Change?

[Ken Hall]

I just had an entire heating/cooling system (including ductwork) replaced and the contractor is urging me to use Honeywell FC40R filters.

I've always used the 80¢ blue spun fiberglass filters and change them very regularly -- about 12 times a year.

These Honeywell FC40R filters cost a lot and don't have a particularly high MERV rating. I have two return air grills and the price for two of these filters will be about $150. The contractor says I should change them every 6 months or $300 a year. WOW!. That's a *LOT* more that the cheapie filters I've been using.

My questions are:

QUESTION 1: Since I have two filters rather than one they load up less. How can I tell if the filter *really* needs replacement? I didn't mind throwing away 80¢, but the idea of throwing away $80 unnecessarily -- be still my heart.

QUESTION 2: Is the protection afforded by these Rolls Royce priced filters really going to do enough to pay for themselves, or is this just a "feel good" thing? [We don't have allergies and have been happy with the air quality with the cheapie filters]

-- Ken

[Ken Hall]

-- Ken

[gofish]

moves in and decides to get a better

.8. Then the problems start to show... :(

Thanks Joseph for fixing Steve's 'broken top post'.

Be sure to send him your invoice.....

[gofish]

FWIW, recently I was involved with modifying blueprints submitted by a mechanical engineer for multiple mechanical systems for a client. The mechanical engineers design called for .1 static on the main sa & ra ducts, with a .08 for the branch ducts. Granted, most of the pkg units are belt drive, but typically .1-.08 are very common duct sizing numbers.

If you ever get an opportunity to attend a class on Trane's Residential zoning, by all means attend. Or for that matter any manufacturers zoning class that incorporates 0-100% modulating dampers. You'll see designs on the branches around .04-.05.

FWIW, I design between .06-.08 on all branches and .08-.1 on all plenums & trunks.

Awhile back I had an extremely interesting situation.....an airhandler running at 20,000 cfm was pumping air into a cleanroom. In the clean room were 12" HEPA's, and in the air handler were 2" pleats. About

20% fresh air was being pulled in by the air handler.

The supply from a 10 ton hp was ducted to the return plenum on the air handler. Right next to the supply was the return duct back to the 10 ton hp.

My job was to install another 5 tons into the very same air handler return plenum. Once I tapped the new ducting into the return plenum, the static pressure was so great in the 5 ton pkg return compartment you had to struggle to get the access door back on. Obviously I went with a 1hp high static blower motor for the new 5 ton unit.

I guess my point is, sometimes you gotta do what you gotta do, even if its outside your normal comfort curve of experience or training.

moves in and decides to get a better

.8. Then the problems start to show... :(

[Joseph]

The .7/.8 were just averages I pulled from my fleeting memory. Quite a few times the SPs went over 1.0". I was theorizing that units running for extended periods at High Static Pressures would see premature unit failures.

It's been a dozen years since I've done any installations but I have had to go in after and re-duct to bring the SP down to .5". When I was installing (mostly Trane units using flex!) I never had any difficulties keeping the .5" SP pressure required. In the repairs I have made almost all of them were because of undersized R@ ducts (hacks) or some type of electrostatic filter. I don't know if I buy the idea of a wet coil always being = .3".

Joseph