A while back I had a local HVAC tech take a look at my system and was told that my duct work was too small resulting in excessive static pressure. He also stated that my unit may be oversized. His suggestion was to replace the current unit and install a second unit (heatpump) in the attic.After reading this forum for several months in an effort to figure out the best way to solve my issue I have decided that I want to stick with a single unit. In doing so I will have to upgrade my duct work primarily the runs to the 2nd floor. What I have is a trunk in the basement and several vertical ducts going throught the wall to the 2nd floor. It seems that there must be some sort of trunk on the 2nd floor since the vertical ducts in the wall do not run directly to the registers.
Here is an idea I have and I'm wondering if it's a good option. I would like to run flex in my attic and install registers in the ceiling or walls for the 2nd floor only. I could run a single vertical trunk of what ever size is required to connect the 2nd floor to the unit in the basement. I don't mind if I have to give up some closet space or whatever to make the vertical run. I can drywall and build partitions to hide the duct.
Thanks in advance
That is exactly what I have going on in my house, except instead of in the basement, my unit is in the attic of the first floor (basically on the same level as the second floor) I have a trunk that runs into the attic of the second floor and supplies 3 registers.
The main problem with this is the flex is so long it is restricting the flow pretty bad.
So, in a nutshell, yes it can be done, but use rigid duct as far as possible. Also consider using zoning for comfort reasons.
Hope this helps a little.
If there are any "gas or oil open vented appliances; furnace, hot water heater, in the basement," --the design will have to provide a somewhat positive pressure in the basement area so there is "NO pulling" of the combustion air and/or vent gases into the basement and/or the return air system.
I do have a gas furnace in the basement so I guess that needs to be considered. As far as flex from the basement to the attic I was not thinking of doing that. I was proposing a trunk using normal metal duct either round or square for the vertical run connecting to a metal truck in the attic with flex to each room.
I was just asking if in general it's OK to have a duct system in which there is a trunk in the basement for the 1st level then a trunk in the attic for the 2nd floor with a single vertical trunk connecting them. In my case I now have multiple small trunks going from the basement to the attic and it looks as though they are small so as to fit between the studs.
I am proposing to sacrifice a closet or the cornor of two rooms in order to run a single large verticle trunk to connect the basement trunk to the attic trunk.
It will be fine,IF you have a Manual J,S and D performed, by a competent HVAC contractor
M-J to determine the btus and cfms neded for each room
M-S to select the correct size system
M-D to size the duct system to allow the btus/cfms required ,from the properly selected system ,to get to the proper rooms and provide the comfort it should.