I give up! Which way does the arrow point? I hear that question about a hundred times every year, and I also see hundreds of furnace filters installed backwards. To make things simple, I tell these customers the arrow always points towards the furnace and then I draw an arrow on the cold air return right next to the filter slot pointing in the correct direction.
No Arrows No Problem
It is true that some filters don’t have little arrows on them showing the proper air flow. These filters are usually bidirectional, and they work efficiently installed either way. The filters with arrows on them defiantly need to be installed correctly. These types of filters usually have some type of built in reinforcement that prevents them from getting sucked into the blower when they begin to get dirty. When installed backwards, the reinforcement is not able to stabilize the filter, and next thing you know your blower motor has been destroyed.
Pleated and Fiberglass Filters
Pleated fitters are the most common type of filter I pull out of a blower wheel. If installed improperly and allowed to get to dirty, they will get sucked into the blower. The problem is not that they are cheaply constructed. The problem is that they filter out such small particles of dust and dirt that they clog up quicker than you may expect. Checking the filter on a monthly basis will help ensure efficient furnace or air conditioner operation, and keep the filter out of the blower compartment. Just because the filter is labeled to last for 90 days doesn’t mean it is actually going to last 90 days.
If you use the green or blue fiberglass filters, monthly filter changes are still important. These filters allow more dust and dirt pass through them so they don’t get dirty as quickly as a pleated filter. However, they do get plugged up and they can get sucked into the blower. Also, these filters allow more particles to collect inside your system which can also cause problems for the unit if you are not having it cleaned yearly by an HVAC professional.
Monthly Filter Checks
My suggestion to every homeowner is to get in the habit of checking your furnace filter monthly. Whether you have a 30 day, 90 day or six month filter, checking your filter monthly can head off potential problems and is a good practice for any proactive homeowner.