Use 1" furnace filter instead of 5" ?

[johnny]

replying to Allie, johnny wrote: Great idea. I think that will work fine. I am going to do the same thing.

[johnny]

replying to Allie, johnny wrote: I think the idea of using a frame to take up the extra space will work fine. I plan on doing exactly that.

[Ed Pawlowski]

Better deal but less filtering surface. Less surface means more frequent changes. False economy.

[trader_4]

Might still work out if the 4" ones are significantly less expensive though. IDK about relying on the thinner filter being sucked into place part. IDK what kind of situation they have. I have what's either a 4 or 5 inch pleated filter, I change it once a year or once every two years depending on how it looks and it doesn't get dirty fast.

[TimR]

The purpose of the filter is to protect the equipment, not the people. You want to keep the coils clean.

The air that hits the filter comes from inside the house. You've already breathed it.

[trader_4]

I thought it was actually both. And that to protect the eqpt, even a minimal filter will do that. That's why they put a spot for a 1" filter in the typical furnace. To filter out allergens, finer particles requires the higher rated filters. I've liven for many years in homes that just had the 1" filter, never had any eqpt problems.

[TimR]

That's what I think, too, but it makes sense to me that filtering finer particles means more resistance to air flow which requires a bigger fan which uses more electricity etc. And if your resistance to air flow is too much you starve the coil of air and you get freezups.

I use the 1 inch filters and I change them when I hear the air noise increase.

I think my refrigerator coils catch the most dust anyway.

[trader_4]

The finer filters have deep pleats to substantially increase the surface area to at least partially offset that.

[gfretwell]

The pleated paper filter, like a Space Guard have a whole lot more surface area so it makes up for how much restriction there is per square foot. I still have a pre filter in front of mine to stop the big stuff. That one is washable. There is a gauge on the plenum to see when the restriction becomes excessive. I usually swap out the element at around 0.2-0.3" H2O. A new filter cruises at around 0.07".

[Dan]

These thick filters suck. If you live in a cold climate expect your furnace humidifier to essentially stop working!!! All the humidity gets filtered out and your house becomes a Sahara desert!!!

[angelica...]

What humidifier? Forced-air furnace, Michigan. Never saw the need for a humidifier.

Cindy Hamilton

[invalid unparseable]

I have one but humidifier is past the filter and filter would not filter out humidity.

I read humidity between 30 and 50 percent is best. Surprised you do not need it in colder climate. If your lips are cracking and doors are sticking due to shrinking wood in the house than you need one.

[trader_4]

What's the indoor humidity in winter? Typically without a humidifier the humidity drops to a low level and you would feel more comfortable and use less energy at a lower temp if it was 40 - 45% humidity.

[trader_4]

Same here. But there are bypass type humidifiers where they recycle some of the hot air through the humidifier and back into the return duct, where it will go through the filter. I never thought about that affecting the filter. But seems like it should not, given that they only recycle a small portion of the output air and that gets mixed with a lot of the rest of the air before hitting the filter. But i suppose it's possible that the filter could get enough moisture in it so that it might be a problem. How the house could be like a desert makes no sense. The filter can only hold a certain amount of water, all the rest that the humidifier puts out has to go into the house.

[Marilyn Manson]

The more dust on the filter, the more moisture it will retain. The dust will get "wet", thicken up and block air flow.

Not saying it would dip to the (probably exaggerated) desert level, but it could be a combination of things causing Dan's issues.

[Clare Snyder]

The 5" filter has a LOT more surface area and is much higher flowing. All the air goes through 5 times (or more) as much surface area ONCE. With 5 filters stacked all the air goes through the smaller surface area 5 TIMES. The smaller surface area increases the pressure drop - and you multiply it by 5. Just a somewhat educated guess the restriction of 5 stacked 1 inch filters is (at very minimim) about 8 to 10 times the restriction of the 5 inch filter

[angelica...]

Nope. None of that. The doors sometimes stick in the summer when the humidity is high.

Cindy Hamilton

[angelica...]

I have no idea. Maybe I'll find out. I have a fairly crappy humidity gauge on the screen porch; I could see what happens when I bring it inside.

Cindy Hamilton

[angelica...]

That turned out to be easier than I thought. My husband has some sort of device that measures R.H. for his gun safe, but it's been in the living room for a while.

About 36.5% at night and 40% at the warmest part of the day.

I can live with that.

Cindy Hamilton

[TimR]

Comfort is a combination of temperature and humidity. According to my psych chart, at 40% humidity the low end of the comfort scale is 69 F. My thermostat is set at 68 so technically we're below that, but it's easy enough to grab a sweatshirt.

And that neglects radiative cooling from your body to exterior walls, if they are cold.