FAU in mobile home

[Chris Weekly]

Mobile home had a Carrier Weathermaker 8000 installed.
The manufactures plate for the FAU said "This furnace is for indoor installation in a building constructed on site." That pretty well excludes this from being a properly installed furnace. Can anyone elaborate on why? ....and can I get more than "..because they said so..."?
thanks for any info.
Oh, and that is the custom return and filter on top of the furnace. That might be another reason - altering manufacturers equipment.

[Jerry Peck]

Mobile home had a Carrier Weathermaker 8000 installed.
The manufactures plate for the FAU said "This furnace is for indoor installation in a building constructed on site." That pretty well excludes this from being a properly installed furnace. Can anyone elaborate on why? ....and can I get more than "..because they said so..."?
thanks for any info.

Because they never listed the unit for use "in" a manufactured "mobile" home - mobile homes burn much quicker than site built homes do, and only those products listed as approved for use in 'mobile homes' are allowed for use "in" mobile homes.

That problem is solved 'down here' by having a package unit installed 'outside' the mobile home, only duct work enters underneath the mobile home and connects to the mobile home.

You will find that water heaters have similar limitations, i.e., 'suitable for use in mobile homes' or they are not.

Sounds to be like someone did a change-out and replaced the FAU with an unapproved unit, either because they did not know what they were doing, or because it cost less ... not sure which, but I would think that a unit for a mobile home would cost less?

[Ben Tressel]

Older mobile homes usually have ducts with less free air space and the interior volume is much less than a stick built home, so the furnace may not be able to move as much air through the system as it wants to. I believe this is mainly a warranty issue. As a side note, being that the return is in the furnace closet with louvered doors I seriously doubt enough combustion air is getting in there. They may want to consider removing that door.

[Gregory Booth]

.............what others have said. Also, a listed unit will utilize a specific (cottage) base that mounts to the floor on which the furnace cabinet then fastens to.........Greg

[Chris Weekly]

Because they never listed the unit for use "in" a manufactured "mobile" home - mobile homes burn much quicker than site built homes do, and only those products listed as approved for use in 'mobile homes' are allowed for use "in" mobile homes.

That problem is solved 'down here' by having a package unit installed 'outside' the mobile home, only duct work enters underneath the mobile home and connects to the mobile home.

That's good info Jerry and makes sense. Inside vs outside is a good distinction to note. The setup inside has to be a pretty well sealed installation to prevent air communication and contamination. This FAU also was brought and installed from a previous site, a used piece of equipment - I could see that there had been holes and openings for a different setup.

...and Ben and Gregory those are good points too. The air flow or volume would definitely be impacted with the standard rectangular mobile home ducts and teeny floor registers.
Thanks all for your replies