the horizontal installation had a big sag in the flue and furnace was out of level tilted away from the drain. exhaust fitting by furnace not glued. drain fittings not glued. no intake pipe, just a 2" hole in the cabinet to draw fuzzy attic air; unused hole for intake on nice vertical concentric way over on the other side of attic. furnace oversized.

we levelled the furnace; pushed, pulled, braced the flue and got it to fire and run after we flushed 2ndary exchanger with nitrogen to get out excess water.

the builder is still bound by his one year warranty. he asks can we fix it? Original installer folded up and gone. (there's a shocker.)

No definitive word yet, but boss is informed Rheem says you CAN put their 90 percenter in the attic---permissible but not advisable was best guess late Friday afternoon after the smart guys had all gone home.

So as it stands Monday we go back to pipe the intake, we heat-tape and insulate drains, insulate outside furnace cabinet and cross our fingers, I guess. Maybe we ought to plug in a trouble light, stuff it under and leave it turned on? Hah

Thoughts, anyone? (Were I the cheese I would say we are changing out to 80%er, like it or don't. Yeah, I know, the green scrip w/ satanic Illuminist symbolism.)

Oh, yeah, location middle of Missouri and it does get cold. Occasionally real cold. Building a conditioned-space room in the attic for furnace apparently not an option.

(sorry, don't have model and ser. number, they're in other truck)