Furnace Filter

[Hall]

During the A/C season my unit runs a lot, so I change them once a month.

In our climate, anymore we go from AC use to running the furnace. If we're lucky, we might get 2-3 days of in-between weather where we can open windows and turn the unit off. Last night, we had to turn the AC on overnight because of humidity and this evening, the heat is on.

 

[2strokeNorthstar]

I did maintenance for a cheapskate apartment complex. They used pre filters as the filter. The ducts were coated with grime and were disgusting. I've used the 3m Filtrete filters and the ducting is clean as can be. The hvac guy that installed my parents new furnace said "Filters are cheap new furnaces and parts aren't. "

What's a pre-filter? I'm picturing those socks you put over a K&N

 

[97prizm]

What's a pre-filter? I'm picturing those socks you put over a K&N

Washable filterEssentially it's one of those cut to fit mesh filters that are really coarse. They filter out large dust particles but don't catch mutch of anything else.

 

[2strokeNorthstar]

Washable filterEssentially it's one of those cut to fit mesh filters that are really coarse. They filter out large dust particles but don't catch mutch of anything else.

Oh, I used one of those in our old house, whoops.

 

[Snagglefoot]

My furnace came with a 4 inch thick Merv 8. I think I’ll change it today.

Here it is beside the new own. Some of this is smoke particles.

 

[Hall]

Some of this is smoke particles.

A few months ago, in SW Ohio, we had haze from the wildfires from Canada and one time, it lasted almost a week. After that happened, our furnace filter was the dirtiest I've ever seen.

 

[HowAboutThis]

A few months ago, in SW Ohio, we had haze from the wildfires from Canada and one time, it lasted almost a week. After that happened, our furnace filter was the dirtiest I've ever seen.

We live in an area that has forest fires within 50 miles almost every year. That's why I like running MERV 10+. But I might drop to 8 unless it's an active fire month due to what people here are mentioning.

 

[facility1]

have a merv 11 carbon infused filter ,its 1 inch thick,,have pets &change out every 2-3 months,has over sized filter plenum.

 

[hrv]

I use a MERV 5 or less and change it every 30 to 60 days...

 

[Rand]

I use a MERV 5 or less and change it every 30 to 60 days...

merv or FPR? I rarely see merv 5 unless I order online.

 

[paulswagelock]

Hopefully this is an other filters topic. Where do y'all get your furnace filters at? The HVAC tech that looked our furnace over today charged me $6 for a MERV 10. I thought that was a great deal! The big box and home stores are $10+ for anything MERV 10 or higher. I've seen some online places for close to $6. Anyone use the online stores and have good luck? Any had awful luck? Given the 3 oil filters I tried buying from Amazon had dented cans I'm hesitant to buy crushed and destroyed furnace filters online. Maybe I just call the HVAC place and ask if I can get 10 for $60?

I use Aerostar Merv 8 filters from Amazon. $6 each in a 6 pack, well made, not too flimsy, good bang for the buck.

 

[hrv]

merv or FPR? I rarely see merv 5 unless I order online.

I see MERV on a lot of filters that I purchase at Wal Mart and Lowes ...sometimes you have to look and the side of the filter for it...

 

[tcp71]

our new (june) furnace has a GeneralAire MAC 1400 Filter slot. Requires a GeneralAire 4541 filter. It came with a MERV 11 and I bought a couple of filters. The system reminded me to change the filter after 4 months, and I did. Quite a bit of fine grey dust covering the filter so a 4 month change cycle seems to be right. Filters are **** expensive:

 

[Rand]

not that bad for 5" thick filter. just divide that by 5 and you would have 6$ per 1" filter.

what size house is this I'd expect they could last 6months esp during summer. that is a pretty beefy filter.

Thats also in CAD pesos.

 

[Kantaro]

Be wary of low quality filters that don't publish static pressure! Even cheap MERV8 filters can have a higher pressure drop than something like a 3M Filtrete 1900 (MERV 13 equivalent).

I personally run Camfil 30/30 MERV8 all year and change every 2500 hrs of run time, which is fortunately tracked by the air handler controller. Camfil filters are very reasonably priced online and the publish full technical specifications, I presume because they are meant for commercial applications.

I do monitor air quality during wild fires and switch to a 3M Filtrete 1900 if PM2.5 levels are elevated. Both have the same static pressure of 0.23 IWC at 350 fpm, but the latter costs significantly more so I use it only when required.

 

[JWC86]

Has anyone ever messed around with putting a pressure gauge on the “pressure“ side of the filter? It seems I remember seeing that done where?

 

[JustinH]

I have a 5 inch wide filter in my house. I order them from Nordic Pure, they are about half the price of lowes and they deliver next day in Texas.

 

[oil pan 4]

Interesting. I was reading anything over a MERV 12 is a bad idea. The furnace tech told me MERV 10 is a good number during wildfire season with AC. That's what he installed for winter, said they get them from their Rheem supplier and they're a solid filter. Didn't realize in the land of BITOG rock catchers would be so popular for a furnace but the complete opposite for a car engine that shouldn't have anything floating in it. We get horrible pollen in the spring and fall. I about die without allergy meds and 10 Flonase sprays per day in April through June.

I built filter fans. Uses quiet bathroom fans to pull air through two 24x24 inch filter.
My pm2.5 meter usually reads about a 0 in the summer.
I use the smallest filtering 3m air filters they sell at Lowes. The purple ones.

 

[John105]

This is a touchy subject for me. New system in summer 2020 came with an Aprilaire system that takes the 413.

I bought replacements on amazon, 4 for $121. I thought that was really pricey.

Now they are 4 for $193. I check the price everyday and will buy more when they are $121. So far, that's never happened in a year

 

[oil pan 4]

This is a touchy subject for me. New system in summer 2020 came with an Aprilaire system that takes the 413.

I bought replacements on amazon, 4 for $121. I thought that was really pricey.

Now they are 4 for $193. I check the price everyday and will buy more when they are $121. So far, that's never happened in a year

For that price it's time for whatever I can find at the store and some duct tape. Maybe a lot of duct tape.