Running new ducting

[Zaffer]

I just bought a house built in 1919 and it has central A/C installed, but I need to run new ducting as the current stuff is not insulated and is coming apart. What size, typically, should I run for the main trunk (downstairs, top-bottom feed, and upstairs) and what size should I run to the individual rooms?

Here is the basic layout of the house:
Downstairs:
Front hall - 10x13
Kitchen - 12x13
Living room - 13x14
Dining room - 13x14

Upstairs:
Bathroom - 5x7
Front bedroom - 13x14
Back bedroom - 13x14
Office - 8x11

It is a typical four-square lay out in the house. Total square footage is 1,351 sq. ft. The unit is barely adequate enough for the house, but it works for now. Should I run 6" flex to all of the individual rooms? All of the rooms, except for the bathroom and office, have two registers in them. The downstairs ones are 2x10's and the upstairs ones are 8"(?) circular.

Any advice would be wonderful!

[Mrfixit39]

No Diyers Welcome!

[lolson]

after you calculate the SP, VP, CFM, Area, Throw then you can figure it out.
read the sight rules no DIYers
call a pro

[raidersfan7]

sorry guy u need to call a contractor

[dash]

When you look for a Pro,ask" can and will you do a Manual J,S and D ,to determine the load,select the proper size equipment,and design the duct system"??

Keep dialing ,until you get 3 positive answers,as many can't or won't do these.

[Zaffer]

I am realizing that I need to get a professional in there to do it right. I just want to know what I need so that way I can tell if the A/C guy is full of BS. I am trying to expand my knowledge so I won't be taken advantage of.

Thanks for those who have provided some useful info.

Anything else I should ask of be aware of?

[Zaffer]

I am realizing that I need to get a professional in there to do it right. I just want to know what I need so that way I can tell if the A/C guy is full of BS. I am trying to expand my knowledge so I won't be taken advantage of.

Thanks for those who have provided some useful info.

Anything else I should ask or be aware of?

[beenthere]

If you want to know what size ducts you need.
Buy the manuals Dash listed, and study them, then you will be able to figure out what sizes.




Room size doesn't tell you what CFM a room needs.

[Zaffer]

Okay, thanks!