Ductwork Woes

[yankeemongiat]

I bought a 1960's Ranch Style Home and had a Mechanical Engineer check it out before purchase. He gave the house a clean bill of health, well the following Summer the AC went out and I had a new Furnace and AC Unit installed.
The Installer didn't say nothing at the time about the ductwork not being big enough to handle the load. I have about a 15 to 20 degree temperature difference between rooms because of the ductwork. The Ductwork consists of a 6 foot verticle trunk leading to the atticwhere all ducts tie in and run anywhere from 14 foot to 50 foot across the attic(it looks like an octopus up there). These ducts are all 4 inch runs, so you can imagine the drop in pressure to the farthest ones.
I am wanting to install a truck line down the middle of the attic and tie in all existing ducts and add a few more for the bathrooms , which have none as of now. I need to know what size truck line to use and where to transition down to keep my pressure right, also would it be better to use bent steel duct or just buy the flexible round insulated duct?
My house is 2300 sqft, 3 bedroom, 2 bath, dining room, living room kitchen and laundry. I can supply pictures and drawings of the existing ducting if needed. Any professional help will be gratefully accepted and very much appreciated.
Thanks
Michael Roberts

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[Jay11J]

4" ?? Yikes!

Did you call the installing dealer and asked them if they were aware of the duct sizes?

This is a pretty big job for DIY.. Be best to have the pro in and do it right. They got the tools and what not to make the duct work.

I would suggest metal duct for the runs and wrapped in insulation.

[yankeemongiat]

4" yikes!! Yeah thats what I thought, I called them and they told me that I had never asked about the ductwork so they just tied into it as it was. They also told me I was getting a very energy efficient heating and air system. What I got was a Fridgedaire with a SEER of 10, not what I expected for an efficient system.

[Jay11J]

Humm.. an odd company that didn't check the duct works when they did the works...

10 SEER is a low end , where highest you can get is 19 SEER.

For the Midwest area, 13 is about ideal to have since cooling season is short.

As for duct work, I'd call another company and get a bid on the job.

Did your coil freeze up on you with the small ducts?

[Ed Imeduc]

Think about it. If you want to do it you should use Duct board for the trunk line down each way and come off it with 6": round flex insulated to each register now the tools run about $300 for that . Or you can do a spider there thats like two 6" out of an 8" two 8" out of a 10" Two 10" out of a 14" you still have to make boxs for this out of duct board. then all the pipe that is left over . Yes you can do it for sure but will you be better off getting 3 bids for the job. You could take out all the old stuff up there cut new registers holes in All of that helps .You dont say what tons AC you have there. But a good job works out to 60sq" to 80sq" per ton in the duct work.

ED ;)