Does mold grow when trapped on my air filter?

[tonyclifton]

I have a Trane 4TEE3F31 air handler which uses the 1" (looks more like 3/4") 20x20 air filters. I buy the cheap 'Basic' level filtration filters at my local Lowes because the others just seem so darn expensive and I'm skeptical (ignorant) that they would really do much better? One thing I notice when changing them is I usually see a thin layer of dark mold and I always wonder if the mold is trapped but then continues to grow and release spores?

I would like to upgrade to higher filtration level filter but it's hard when I pay $4 each now and the next higher up level (11 MERV) is $12 each.

[pecmsg]

If you want a better filter invest in a 4" filter cabinet!

3M is good at marketing, not at making filters!

[Snapperhead]

I cant remember ever seeing mold on a filter ....

Do you burn candles ? Vape ?

[kdean1]

3M filters are too restrictive for most applications. IMO, Aprilaire makes the best filter. They have a very low pressure drop.
The purpose of the air filter is to keep the equipment clean. Why do you feel the need for a better filter.

[tonyclifton]

Why do you feel the need for a better filter.

Thank you for the question. I am not sure what to think really. Perhaps I am just affected by the marketing as I stand there looking at the higher filtration rates while shopping and wondering if I'm being too cheap by getting the lowest rated filter. That said I do live on a very wooded lot and between us and the dog we track in a lot of dust, and we run a wood stove which I know puts out a good bit of dust in the winter. And like I said in my original post I'm a little perplexed about the mold(?) I see on my filter when I change it every couple of months. The filter I use says it is rated to be changed every 90 days and I try to do it every 60 days but sometimes I slip so I vary between 2 and 4 months.

[Sleuth]

.
I can see the wood stove causing the problem dust you're seeing. Stick with the cheap fiilters. They're disposable and doing their job....
..

[kdean1]

If local air filtration is something that would help, here's a DIY design for a high efficiency filter system known as the Comparetto Cube.

https://www.energyvanguard.com/blog/...le-air-cleaner

[tonyclifton]

I like that cube idea although it has me wondering about something I've always thought about. Wouldn't the volume of air being filtered be fairly limited to air movement in that area? I admit I know nothing about air movement. I would think that cube would only be good for that room and maybe a little additional air that might flow in or out of that room.

My gym has some kind of device they installed that supposedly filters out covid - it is mounted up on a wall. I am skeptical it treats all the air equally and adequately given it is just one device.

[teddy bear]

I have a Trane 4TEE3F31 air handler which uses the 1" (looks more like 3/4") 20x20 air filters. I buy the cheap 'Basic' level filtration filters at my local Lowes because the others just seem so darn expensive and I'm skeptical (ignorant) that they would really do much better? One thing I notice when changing them is I usually see a thin layer of dark mold and I always wonder if the mold is trapped but then continues to grow and release spores?

I would like to upgrade to higher filtration level filter but it's hard when I pay $4 each now and the next higher up level (11 MERV) is $12 each.

Mold spores traped on a filter will not grow if the humidity is less than 60%RH. Most molds require steady moisture levels 70-100%RH to germinate the mold spore.

Good comments on the merv ratings. Merv 11 is ok, 4" deep merv 13 ideal for most air handlers.

Fresh air change in 3-4 hours also important to purge indoor pollutants and renew oxygen.

Maintain <60%RH also important for minimizing mold and dust mite growth.

Keep us posted if you make changes.

Regards Teddy Bear

[kdean1]

I like that cube idea although it has me wondering about something I've always thought about. Wouldn't the volume of air being filtered be fairly limited to air movement in that area? I admit I know nothing about air movement. I would think that cube would only be good for that room and maybe a little additional air that might flow in or out of that room.

My gym has some kind of device they installed that supposedly filters out covid - it is mounted up on a wall. I am skeptical it treats all the air equally and adequately given it is just one device.

That is correct. But the cube is easy to move as the need arises. Another benefit is this, if your duct system leaks (as many do), because the cube is not connected to the ducts, it won't increase leaks in ducts which are outside the envelope.
I suggested them to people I know who were near the recent fires. They could not open windows because of the pervasive smoke so the cube was ideal for them.