HVAC Filters

[Jsf721]

I just finished a project in my house that involved a lot dry wall work. Made a dusty mess so I decided after it was all cleaned up I decided to wait a week and change the air filters.

I had one left in my stock, its a 3M Filtrete (red pack) I used to pay about 5 bucks each maybe a year ago. Went to home depot and they no longer carry 3M filtrete, nor do they carry 3M filters at all. 100% of the stock in the 16x20x1 and most other 1" thick sizes was HDX brand. I am sure they are OK but those are now about $ 6.99 if you buy 4 or $ 13.99 each.

What happened to the price on these? I checked Lowes and the pricing is way up too 3M are 46.00 for 2 filters! Inflation is high but this is crazy. I usually change my filters every 3 months. Manufacture recommends monthly but they are hardly dirty after 3 months.

Is anyone using the washable filters?

https://www.amazon.com/UBeesize-Electrostatic-Reusable-Washable-Permanent/dp/B0C7C3R97K?tag=atomicindus08-20

Any better place to buy these?

What MERV number are you guy's using and why? Not sure I know what it means. I though it was the level of filtering and more may not be needed, correct?

 

[Jgaz]

Air Filter Comparison Chart that I found online:

Here are the filtration comparisons between FPR and MERV:
FPR 4 -5 is the same as MERV Ratings 6 – 8.
FPR 6 – 7 is the same as MERV Ratings 8 - 11.
FPR 8 – 9 is the same as MERV Rating 11.

I use FPR 4 -5 or MERV Ratings 6 – 8 at the recommendation of my A/C guy

Cant help you on the price but I’m interested in other member’s answers.
I still have two filters left in my stash.

 

[racecougar]

Merv 15 unit plus charged grid and UV systems in the house here, as the house came with it all. I run those filters for a year, at which point they're hardly dirty. They get a second life in the air scrubber in the shop, with Merv 9 pre-filters taking the brunt of the abuse ahead of them.

 

[Dagny]

Duct systems are all different .Use as good of filter as you can without over heating your furnace. this is almost never a filtrete.

 

[BrandonV]

What MERV number are you guy's using and why?

I use a Filtrate 1900 which is a MERV 13. Tried filters with a lower rating but my tests along with the state of California found that the added pleats lowered the static pressure drop versus other 1" filters.

I change it monthly to make sure it doesn't stress the equipment.

 

[danski0224]

Went to home depot and they no longer carry 3M filtrete, nor do they carry 3M filters at all. 100% of the stock in the 16x20x1 and most other 1" thick sizes was HDX brand. I am sure they are OK but those are now about $ 6.99 if you buy 4 or $ 13.99 each.

What happened to the price on these?

Orange store is moving to private label products wherever they can, and have been doing it for over 20 years. All box stores are doing this, and this is also why Harbor freight has so many different brand names now.

Four main reasons:

1. Hassle customers for price matching, as the brand is not the same
2. More profit
3. More profit
4. More profit

I do not know if you have noticed or not, but prices have been trending in an upward direction for a little while now...

I also suspect that your memory is bad. I do not recall any 3M branded filters for less than $10 each for a very long time, loooooooooong before Charlie 19'er.

No one can tell if a filter is really bad just by looking at it (besides the obvious 10 pounds of fuzz stuck in it). One needs to know the system operating parameters and a properly installed device to measure pressure difference.

Almost all residential type systems cannot handle more than a plain old fiberglass air filter, and just change it monthly unless the system is not being used.

 

[Dagny]

Several years ago I started using return air drops that take 4 or 5 inch filters that allow higher merv numbers without the huge temperature rise across the furnace.

 

[bobg03]

My heating and cooling is by an HVAC unit, no furnace. I started using a box filter and when I had it serviced the technician told me to use the single layer green ones and change it monthly. The unit gets serviced 2X a year by the same company and every tech checks to see whats in there and they all say that's the right way, creates less restrictions on the unit and airflow.

In the couple of months that I use neither heat or air, I check it and if it's spotless I let it go another month.

 

[PBCampbell]

I'm not sure about modern systems, but the original idea behind the filter was to keep dust and **** out of the blower motor, hence why you don't need and shouldn't use a high MERV type filter as it's too restrictive and could damage that motor.

 

[BrandonV]

I'm not sure about modern systems, but the original idea behind the filter was to keep dust and **** out of the blower motor, hence why you don't need and shouldn't use a high MERV type filter as it's too restrictive and could damage that motor.

Still applies. The goal is to filter as much air as possible to keep the unit clean while not placing a massive static pressure drop on the blower.

You really can't make any suggestions without measuring the filter over its lifespan with a manometer while knowing the system specifications.

 

[Jim greengo]

I've used the white true blue filters for years,a lot cheaper.
Pull it out and check them once a month,if it's clean shove it back in.
If it's dirty,chuck it.
For around $3.00 a pop they work pretty good.

 

[bonneyman]

I've found that just getting customers to change their filters regularly was more important that getting a certain kind of filter. I mean, putting a high efficiency filter in your unit and then forgetting about it for a year gains the customer nothing. Maybe it'll make things worse.

 

[justinjoyal]

MERV 8 is typical and often recommended as, most of the times, improper ducts are already choking the system.

 

[nadogail]

I buy my filters from Amazon, the prices are very good compared to either the HVAC contractor or the local hardware store.

For the sizes I use, Amazon also beats all Big Box stores.

 

[bonneyman]

I just got zonked for $73 and change for a dozen 20x25x1 pleats Merv 7 at a warehouse that still sells to me wholesale. That's $6 a piece. They used to be around $3.75. Damn inflation!

 

[Denwood]

The Filtrete 1900 pressure drop is hard to beat for a Merv13 1” filter. It has considerably more square footage (as in pleats) than comparable filters. That said, if you want great filtration with a 1 year replace frequency and extremely low pressure drop, then the Lennox X6672 (sold by a few brands) MERV16 16x25x5” filter is pretty hard to beat. I’ve seen it as low as $70 USD.

Specs are very impressive for a MERV16, but again…there is a large surface area of filter material. This one has a charcoal coating as well:

Air Flow Rate (CFM) 659 initial resistance (IWC) .10
Air Flow Rate (CFM) 989 initial resistance (IWC) .17
Air Flow Rate (CFM) 1319 initial resistance (IWC) .24
Air Flow Rate (CFM) 1649 initial resistance (IWC) .32
Air Flow Rate (CFM) 1600 initial resistance (IWC) .31

I’m using these in my HRV fresh air intake filter system along with a charcoal canister (with about 15lbs of charcoal) to deal with wild fire smoke. At the system’s 110 CFM, pressure drop is very, very low across the filter.

If you have room in the HVAC plenum, installing a larger filter housing makes a lot of sense, if PM2.5 levels and IAQ is important to you.

 

[99LeCouch]

A manometer is the way to tell if the filter is plugged or not. Measure the static pressure without the filter and then again with the filter. IIRC don't go over 0.5 inches total of water column for the entire system including a dirty filter. For expensive filters it's well worth the cost to get the maximum lifespan.

 

[Denwood]

You can also throw a differential magnehelic gauge on your furnace with the stationary kit. I have a Dywer 0-3" (https://www.itm.com/product/dwyer-2...pressure-gauge-0-3-0?ksearch_click=magnehelic) and you can use this kit to mount in place on the furnace: https://www.itm.com/product/dwyer-a-605-air-filter-kit-for-use-with-magnehelic-reg;-gauges
It may actually pay for itself in a few years if you can extend use of the more expensive 5" filters.

The Lennox furnace we have uses an ECM motor and has a communicating stat so I don't bother measuring it. Basically you set your desired CFM via the installer interface on the stat, and it maintains those set points regardless of the filter you have in place.