return air

[subzero*psia]

I just bought a 92% furnace made by Goodman, the dealer told me I had to bring my return air in from both sides. To do this I have to make a horse-shoe shape. I am only using one return run joining to both sides of the furnace.

My question... the return is 24 x 12 and the same on both sides, on the sides though it only allows an area of about 9 inches to be cut out by 16 inches high. That seems to defeat the purpose of having the return on both sides? The embossed area for cut-out is more like 20w x 16t inches, to use all that I will have to lay my returns on their sides and connect in the back.... that would allow me to use all of the embossed area on both sides and not have a restriction or smaller opening. Sound like a weiner? Also, can I use 24 x 6 returns on each side since I am feeding off a 24 x12 main run?

[subzero*psia]

Update.... well, I can't use the 6x24 duct on each side... I looked in manual D that answered that question. Now above my 4 ton A-coil (yes... 4 ton... old victorian home... huge) I had very little room for a standard plenum with transitional take-offs because this furnace is in the original mechanical or rather boiler room, which was built to be fire / explosion limiting by its construction. Anyway, I placed an 8x18 metal duct on top of my cased coil and cut out the front to take-off with an 8x16 duct run also. Now I have two 8x18's and one 8x16 trunk lines. Remember this house is old... fire-stops in the walls all sorts of things. To get ductwork upstairs (never had it before) I had to run a 12 inch flex off the bottom of one of the 8x18 trunks etc. (this is why I have the third trunk which is 8x16... to balance my system again.) Off the 12 inch I am installing a 24x24x48 inch fibre board duct and making five 6 inch duct runs and one 4 inch duct run. That will get me roughly 600 cfm upstairs, and I have 1200 cfm down. I haven't fired anything up yet... still have things to do but thought I would keep you posted... I am a refrigeration guy, always took air conditioning guys lightly.... I have to admit you boys deserve alot of credit and I hope you will give me a shout if you see something I need to know.

I know this much... I would rather do new construction for this type of work anyday.... sheesh what a hassle getting ductwork in this house and keeping the basement where it doesn't look shoddy. I have a finished basement which is liveable so installing ductwork is creating limitations on what and how I can accomplish this work... but I am sure that is nothing new to you all. Wish me luck. Maybe when I am done... I will take a picture and post the outcome... I said maybe....