HVAC Ductwork Question

They make all sort of adapters to go from round duct to whatever size opening you want. They also have oval duct to fit in 2X4 contructed walls.

Did anyone do a Manual D and a Manual J calculation to determine if your existing equipment has the capacity and to determine the size ducts you will need?

That's a fairly specialized gazoonie. Might not find it at Home Cheepo. Just envision a venous cutdown, and you'll be OK. Just like on the medical shows.

Can the ducts handle the extra air flow?

No...Don't know what that is. I have pulled permits on the entire job...building, plumbing, electrical and mechanical. Would this be a code thing that the inspector might help with? I was hoping not to hire a contractor.

The Manuals compute the what ducts are needed, the A/C capacity needed and the heating capacity needed for your specific home based on many factors. If this is not done, any conclusions are just guesses. Proper sizing had a great deal to do with how well and efficiently a system will work.

Adding new ducts and loads to an existing system can screw it up.

Any good professional will go to the trouble of doing these calculations before doing such a job. Anyone that does not is just a hack and you may end up redoing the job or suffering poor performance.

I dug out anf finished a 600 sq ft basement and found out in summer all I needed was a return, But my AC cooled the basement to 65 from uninsulated ducts, making it cold. So I insulated the ducts now it is warmer in summer but colder in winter so I added supplys, for winter. Do it right the first time I learned the hard way. I had excess capacity from my hvac, that should be your first question.

Thanks everyone for your input. I went to Home Depot and found that I just needed to cut holes in the round ducts and put on "saddles" . However, I am going to have a pro come and check out the system to see if it will hancdle the capacity. Not sure what I will do if it won't though.

calculations