1" filters

[wyounger]

Yeah, I know 1" filters stink. I will be getting a serious media filter once I can scrape the funds together- maybe an F100. I promise not to install it myself; I want my guy to come back and seal it with mastic and warranty it. In the meantime, though, I'm trying to find a 1" filter that provides *some* level of particle filtration without too much pressure drop.

I've got a 16x25x1" filter rack. The system peaks at 1050-1150 cfm on high heat (depending on if it's set in Comfort or Efficiency). Total static is right at the upper limit (1", on this unit) with something like a 3M Filtrete installed. I ran a 3M Ultra Allergen for a month in this system, and although it didn't look dirty, my tech checked it before he replaced it with his filter on my PM visit, and we had almost 0.40" drop across the filter itself. No wonder 3M doesn't publish the pressure drop for the Filtrete.

I found this MERV 8 filter that seems to have static pressure about as low as anything I can find in an afternoon of Internet sleuthing... and I give Purolator major credit for actually publishing specs for pressure drop across their filters, unlike so much of the competing 1" filter market. I was interested to see how much pressure drops could vary from one brand to the next. I had assumed that a MERV 5 filter would probably be less restrictive than a MERV 8, but that wasn't really the case. Evidently there must really be some difference in the media and pleat design, too.

http://www.purolatorairfilters.com/p...m/DMK80Lit.pdf

For those who don't want to load the PDF, they claim 0.14" drop at 850 cfm and 0.34" at 1400 cfm. That sounds decent to me, but I am just a lowly homeowner who has spent waaaay too much time hanging out on this board. I can get a 12-pack delivered for a little over $50, which kicks 3M's butt.

Anybody else know of a pleated 1" filter that's less restrictive than this? I don't need hyper-allergen-trapping stuff like MERV 11, but I don't want to go back to the 50 cent spun filters, either. Is there a good middle ground out there? Is this it, or should I look at some other 1" filter?

Thank you all, again, and as usual.

[wyounger]

All right. Hearing no responses, I went ahead and bought a case of these, and have one installed now. The total static indicated on the Infinity control runs about the same with these as with the filter the contractor provided on the PM visit- ~0.42" at 700 cfm (the usual airflow with this system), 0.9" at 1050 cfm (high heat in comfort mode). The difference is that my filter is MERV 8, and his didn't state any MERV rating. These Purolator units are pretty well made, and at $52 for a case of a dozen in this size, shipped, I'm pretty pleased.

No, that's not great static pressure, but that's about as well as we've managed with my ductwork. It was clearly built for two tons (barely). Doing much better is going to take major surgery, I'm afraid. This is a new Carrier 58CVA070, and Carrier actually allows up to 1.0" on high heat. I'm still skittish about running at 0.9, though, especially since that's on a brand new filter. It's a good thing I don't mind that I can't run high heat in Efficiency mode, because that calls for 1150 cfm, and dials up 1.05"; the system actually can't sustain it. Blower RPM goes right to 1300. I really, really don't want to burn up an expensive ECM- not in the long run, anyway. If it goes in the warranty period, it's a hassle but not an expense. I'm going to be in this condo a long time, though, and I'd like for the motor to outlast my stay.

At least it very rarely ever runs on high heat; it generally only happens after an overnight setback at less than the design temp (we've had a couple nights at 15, and Atlanta's design temp is 22). Of course, my power went out for almost 24 hours in the last ice storm, and it ran high heat for at least an hour and a half to catch up from that. I have been toying with setting the Infinity to allow only Low stage heat; output from this unit on low is still actually 10-20% over my Manual J heat loss, so it can probably do ok with that. But is it necessary to limit it, or is the system going to survive this kind of static? My contractor doesn't seem concerned, but I'd like a second opinion about its long-term prospects.

Since I'll probably hear something about it in the replies, yes, I looked for smaller furnaces, but this "070" (actually 66k) is Carrier's smallest 80% variable speed furnace, and I really wanted Infinity. The only smaller VS 80s that I am aware of are Heil/Tempstar and Rheem/Ruud- with 50k inputs.

Anybody got an opinion? It's within Carrier specs (I guess the new ECMs can go over the old 0.8" limit?), but 0.9" is still awfully high, and it makes me nervous after what I've learned by reading this board religiously for, what, the last year?

Thanks in advance to all.

[Edited by wyounger on 02-11-2005 at 09:51 AM]

[dash]

1.Your filter should be 24X25,for 1150cfm,this is around 300 fpm,recommended industry standard.

2..9 ESP ,is too high for a clean filter.

3.If it can be set for low fire,and your load calculation is accurate,then thats the easist solution.

4.When you "upgrade" to thicker media filter,size it correctly.Larger will be less PD.

5.There are a lot of things that can be done to reduce the ESP of your duct system.Turning vanes,lower loss fitting,adding returns,creating an additional or parallel trunk,transition between furnace and coil,etc.,etc..Post pictures and sizes of the ducts,for suggestions.

[tinner73]

it's just a filter, change it once a month and be done with it.

[tinner73]

Dash.. is this what you get when you install those Infinity controls? i see this being a REAL nightmare for the installing company.

[dash]

Originally posted by tinner73
Dash.. is this what you get when you install those Infinity controls? i see this being a REAL nightmare for the installing company.

It's exactly what you get with the Infinity!

It's filter change light is a "tattletale" on high ESP ducts systems,and that's a great thing for the homeowner.The HVAC Contractor can no longer ignore these efficiency robbing duct systems.


Simple solution that's been around forever,just test the ESP,before you sell a system,any system,and quote the duct renovations along with the equipment.Be sure to account for dirty blowers and coils that effect the ESP readings,and you'll always be in good shape.


Reading out the ESP on the Infinity is really neat.Just talked to a tech,that was doing a checkup,found high ESP.So he takes out the 3M pleated filters and puts the standard ones back in,shows the customer the difference,and there is no argument.

If the customer wants better filtration,we'll be happy to redesign the return,to accomodate the the better filter(s).