HVAC Repipe - DIY Chatroom

cottagecraft · 09-04-2007, 08:43 PM

I am doing an addition on an older home and it will be easier to bring supply air from the basement HVAC unit up through an access into the attic and then supply each room with conditioned air using insulated flex duct. I plan to use spiral pipe to get to the attic and then convert to flex. Can anyone help me with guidelines for sizing the new ducting? Thanks

Big Bob · 09-04-2007, 08:49 PM

Folks will need to have some idea of # of rooms and size of conditioned space.

cottagecraft · 09-05-2007, 10:47 AM

Thanks for your response. We are looking at 1120 SF with nine rooms including two bedrooms, two baths, entry, living, dining, kitchen, closet. All on one floor with 8' ceilings. My plan is to mount the registers in the ceiling.

Big Bob · 09-05-2007, 11:09 AM

Good info also need size of your HVAC unit and type. You mentioned addition:
how many SF did or are you adding. Was this the existing HVAC unit?
If plant is in basement do you have Return air duct in place?

cottagecraft · 09-05-2007, 11:30 AM

It is an upflow 44,000 BTU -- already installed -- return air not an issue. Two bumpout additions, a bedroom adding 200 sf and a kitchen adding 80 SF. New total is 1120 sf.