We just bought a home with a Goodman furnace (either model GMT or GMTH) and I cannot for the life of me figure out where the furnace goes. The unit sits on the floor and draws the return air from duct in the crawlspace. I removed the side panel and there is a label indicating not to install a filter in the bottom of the unit. The manual mentions filter sizes, but doesn't say where to install them. I'm stuimped.

Can anyone help me out? Our home is pretty dusty, so we'd sure like to get a filter installed.

It is possible that the person that put the furnace in did not make provisions for a filter. I have seen that situation before. If you have a filter location it will be on the return air side of the furnace somewhere.

it is possible that the person that put the furnace in did not make provisions for a filter. I have seen that situation before. If you have a filter location it will be on the return air side of the furnace somewhere.

How would I go about providing for one? Like I said, when I removed the side cover of the furnace there's a label that mentions not installing a filter there... the heat exchanger is directly above the bottom of the unit which rests on the floor. There's a chmber about 18" tall below the heat exchanger.

Actually since you just bought the home it would be a good time to have the furnace looked at by a professional to make sure all is OK. At that time you can ask him if there is a placer for a filter and if not how much will it cost to have some channel installed for a filter. It is best not to guess on filter locations.

Have you taken the door off the blower housing? Are you sure the return isn't in the attic and supply in the crawlspace? This would be a downflow... And have you checked for a filter grille possibly in the ceiling somewhere?

Have you taken the door off of the blower housing?? Are you sure the return isn't in the attic and supply in the crawlspace? This would be a downflow....And have you checked for a filter grille possibly in the ceiling somewhere?


I'm sure the return is in the crawlspace. I haven't seen any sort of in-line filter in the duct, but wouldn't it be unusual for the filter to be on the supply side?

The filter should never be in the supply. Where are the supply registers located? Have you checked the blower compartment? Sometimes a filter rack is installed in the duct just outside the furnace on the return side.

The filter should never be in the supply. Where are the supply registers located? Have you checked the blower compartment? sometimes a filter rack is installed in the duct just outside the furnace on the return side.


The supply registers are either in the ceiling or upper wall.

The unit sits directly on a concrete floor, which has a recess in it. The return duct in the crawlspace is connected to this "well".

I have attached a quick drawing of my system. The red arrow is where I would have expected a filter, but there is a label saying not to install a filter there. If not there, WHERE?

Is the blower in the upper or lower half of the furnace? How many cold air returns do you have?

Is the blower in the upper or lower half of the furnace? How many cold air returns do you have?

The heat exchanger is right above the red arrow, and the AC condenser sits on top of the unit between it and the duct.

There is one return in each bedroom and 2 in the living room. There is no return in the family room, dining, or kitchen.

Pull blower door, there should be a wire thingy, that holds a fiter down to the bottom floor of the furnace.