Which Way To Install Furnace Filter

A furnace with a 3M furnace filter installed

Whether y'all live in a house or an apartment, changing the air filter is a necessary maintenance task considering it improves indoor air quality, keeps the furnace running efficiently, and minimizes runny noses and teary eyes in your household.

While replacing your filter is entirely necessary, incorrectly installing it can lead to inefficient heating, furnace failures, and a high heating bill.

Equally such, you must install the filter in the correct orientation of the airflow. To acquire how to install your air filter the right way, how to notice the airflow direction in your furnace, why the direction matters, and how oftentimes y'all should supersede your filter, continue reading this detailed guide!

Which Way Does the Furnace Filter Go In?

airflow direction arrow on filter and furnace with labels

All furnace filters (or HVAC air filters) have arrows around the edge that indicate in the airflow's direction in your air handler. You should ever install the filter with the arrows pointing in the airflow direction.

The airflow direction of your air handler is as well indicated with arrows on the outside of the filter housing. Then, when installing your new filter, make sure the filter's arrows are pointing in the same direction as the arrows on your gas furnace, as shown in the image to a higher place.

Info: All furnaces have arrows indicating the airflow direction.

What Happens if You lot Put Your Furnace Filter in Backwards?

If you put your HVAC filter in backward, at that place is a slight chance you will harm your furnace. It volition reduce airflow, which puts strain on the HVAC equipment, dramatically reduces efficiency, and increases heating costs.

So, how do y'all know if you've put your furnace filter in backward?

Here are two signs:

If you lot're feeling chilled later on replacing your furnace filter, you will notice that your furnace is running more usual
Your furnace is shutting off before reaching your thermostat's setpoint (short cycling).

Short cycling is a prophylactic feature; information technology shuts off the furnace to prevent damage from overheating. Information technology usually doesn't cause whatever lasting damage to your furnace, so you shouldn't worry about information technology after correcting the filter orientation.

Info: When a backward filter blocks enough airflow, it will trap lots of rut within the furnace. If the heat tin't escape into your habitation, it overheats the furnace and leads to brusque cycling.

Which Mode Does the Airflow in My Furnace?

airflow direction arrows on furnace closeup

To decide the airflow direction in your furnace, all y'all have to do is look for an arrow on the side of information technology. Commonly, furnaces have multiple arrows stamped into the metal near the filter housing.

The arrows point in the management of the airflow. So, if information technology is pointing to the left, that means the air is moving from the right to the left.

If you can't notice an pointer on your furnace, look harder or determine the direction with your hand or a piece of paper.

To decide the airflow direction, if you don't accept an arrow indicating it, turn off your furnace (put the thermostat to "off"), turn the fan pick from "car" to "on," then remove your filter.

Stick your mitt or piece of paper into the filter opening to determine the airflow direction. You should feel the movement easily, merely if non, use a thin canvas of paper– the air volition push it in the direction it is flowing.

Which Way Should the Arrows Point on the Furnace Filter?

The arrows on your furnace filter should e'er bespeak in the same direction equally the airflow. If the air is flowing to the right, the air should signal to the right.

To make things easier, just make sure the arrows on the air filter point in the same direction as the arrows on the air handler.

How to Install Your Furnace Filter

Locate the filter slot. It is positioned adjacent to your furnace, where the main ductwork trunk connects to it.
The filter slot is typically vertical in orientation (but sometimes horizontal), and the filter inserts into the slot much like a chip-mode credit menu goes inside an ATM. Some filter slots will accept a canvas metal cover that matches the ductwork; usually, it has thumbscrews for piece of cake removal.

In one case y'all remove the cover and the old filter, catch the new filter and get fix to insert it. Orient the filter, so its airflow direction arrows match the airflow arrow management on the filter slot and insert it.

Note: Filter slots are usually a "tight fit" for the air filter. HVAC manufacturers exercise this intentionally, so there is less air loss through any gaps.

As such, it may be difficult to squeeze your filter in the slot. Take your time and jerk it back and forth if you're having bug.

When Should You Alter Your Furnace Filter?

The airflow direction is of import when y'all supercede your filter, then is changing information technology out at the proper intervals. How often yous replace your filter depends on various factors, including:

Filter thickness
Filter blazon
Amount of pollen in your area
The corporeality of shedding pets in your dwelling house
Indoor air quality in your dwelling (burning candles, spraying aerosols, smoking, and cooking with fire will all clog a furnace filter faster)
Filter rating

Note: However, the general rule of thumb amongst HVAC professionals is about one to four times a twelvemonth. Sparse filters (i-inch thick) may require replacement one time a calendar month, while thick 5-inch and half-dozen-inch filters could last up to a year.

What Filter Rating Should You Become?

If you're looking for a new furnace filter, y'all've probably seen MERV and HEPA filters. MERV 7 or 8 pleated filters are recommended for most residential HVAC systems.

Yet, many residential furnaces work with MERV ratings up to MERV xiii, but not many. The higher the MERV rating, the more it filters. For instance, MERV 8 filters trap upwardly to 95% of particles as small every bit 5-microns.

Compared to MERV filters, HEPA filters trap a larger percentage of particles but are too dense to work with residential HVAC systems without damaging them.

If you desire the highest level of filtration, choose the highest MERV rating that is compatible with your furnace. You can determine what MERV rating works with your furnace by looking at its manual, contacting the manufacturer, or consulting with an HVAC contractor.

How to Dispose of Your Old Furnace Filter

When you lot remove your onetime filter, be conscientious with it. The filter has collected many months' worth of dust, dander, hair, and pathogens from the air in your domicile.

If you jostle information technology around when you remove it, a lot of these particles could bladder into the air and circulate through your home, which could also prematurely clog your new filter.

When removing an old air filter, you should identify information technology directly into a trash bag and immediately seal it.

Correctly Replacing Filters is Important

When you lot supervene upon the air filter in your furnace, ensure you insert it in the correct orientation. The filter slot on your furnace and the filter will both take arrows indicating the airflow direction.

When you lot insert the new filter, install it so its arrows point the same direction as the airflow arrows on the filter housing on the air handler. You can as well use your hand to determine the airflow management if needed.

Replacing your filter in the incorrect style will reduce your furnace's heating efficiency, reduce airflow, crusade short cycling, increase your heating neb, and could crusade equipment failure. Accept your time and install information technology the right mode the commencement time.