What uh.. what way does this furnace filter go in?

Figgy

I cleaned one of my two washable furnace filters last night. Normally, I dunk it in a laundry tub of soapy water and then do it again with clean water. This time, it came apart partially while cleaning, so I figured I'd just take it all apart and wash the actual filter piece by machine. That part worked out great, and the filter now looks like new. It went back together without much trouble, too.

The problem is, I forget which way the filter went in originally. There is an arrow on the filter frame itself, but since I removed the filter and put it back in, there's a 50/50 shot that it's pointing the wrong way.

I thought I'd just look at the other filter, but alas it's different and the filter is the same colour on both sides. This one has a pale green colour on one side and a light grey on the other. Anyone have a filter like this and know what way air flows through?

Zombie Nirvana

The arrow should point in the direction of air flow. Oh, I see what you did now... didn't really comprehend what I was reading. My guess is that the light gray side was the intake side, since it was likely caked in dust. Which is why the other side is still relatively green. In which case that looks like the back of the filter which would face the furnace/blower. Also, you say you have two of them... can't you just check the other or is it different? That side (green) does look pretty dense in the photo.

Zombie Nirvana

And this post is now redundant.

zepherin

I have a related question, in this case the filter looks like it is made of the same material all the way accross, if the shape doesn prohibit it. Does it really matter which way it goes in as long as it sits in there properly?

Zombie Nirvana

The intake side is made of denser fabric or are you talking rotational orientation? In which case it doesn't matter.

zepherin

I meant rotational. thx

Donovan Puppyfucker

In my experience with multilayer filters, the finest layer is the last to see any airflow. Coarsest side to intake, always.

Figgy

Thanks, guys. I'll go with that.

Unfortunately, the furnace stopped working today so I guess it doesn't matter :P

Figgy

double.

Nosf

That happened with an old furnace in a house i lived in, it seemed to conk out until we replaced the filter and then it fired back up. Older furnace too, didn't see how it was tripping a sensor, or if it was coincedental.

Pantshandshake

Well, if it happens to be a new enough furnace, I can see how it might shut down because of insufficient airflow due to a crapped up filter. Yes, that's a technical term.