How much air do you for a 150,000 NG Furnace....Not

[mh heating]

Went to do a bid the other day. This is what I found on a 37 year furnace. Tri level home with main return in bottom bedroom behind the tv, behind tight louvered door, under stair well, through 1/3 block 16x20 filter, into small chase then to a 8x17 opening to furnace. There is another opening in chase that goes to a very small flat non filtered grill. I cant believe it didnt burn up

[Hvac216]

That old stuff hold up better when it's treated like crap. I found a 30 year old 100k Rheem a couple weeks ago with almost no return. Furnace was sitting on 4 1 1/2" bricks with nothing cut for a return. Had to look hard to find a small crack in the heat exchanger. New stuff wouldn't make it more than a couple years like that if their lucky.

[icesailor]

That's better than what a long passed installer used to do where I work. The only return was that you left the door to the cellar open.

[Gus-Herb94]

Had a 1960, 75,000 BTU Carrier furnace run fine for 47 years on two 6" metal returns that went to a tiny grille behind a built in TV cabinet with louvered doors. Thermostat was kept up real high, blower door whistled like crazy and supply ran hot as hell. HX looked perfect when it was removed...

[icesailor]

They don't make HX'ers like they used to.

[JES]

well it looks like you looked everywhere. did you ever find the furnace?? lol

[Jkb79]

So that's how u drill a square hole... And here I was waiting time using a sawzall to cut my square lol...

[sweat hog]

Looks like the volacity kept it clean and the leaks kept it alive.

[gravity]

you need ~ 1500 cfm for 150,000 input btu atmospheric vent