Supply line register in vented attic
I recently moved to Georgia and had new HVAC systems installed in my 15 year old house. The main floor and basement have a zoned system that works great. The 2nd floor has an attic unit but has a hard time keeping the rooms cool when it get’s into the 90s outside. I have a vented attic that gets extremely hot. I had a thought on a possible solution but wanted to get some input…
One of the attic ducts feeds a chase that brings cold air to a register in the 1st floor living room. This doesn’t make sense to me because there is no issue with keeping the 1st floor cool. Instead of feeding cool air downstairs, if I redirected this duct to a register in the attic would that help create a positive pressure to push the hot air out the ridge vents and to help keep the 2nd floor cooler?
Thanks,
Dan
GBA Detail Library
A collection of one thousand construction details organized by climate and house part
Replies
You’d also be depressurizing your house and probably not really accomplishing anything. Everyone here is going to tell you that the best solution is to not have mechanicals in the attic, but you’re probably stuck with that one. The best option is to convert the attic to conditioned space, or at least the portion of the attic that houses the HVAC unit and most of the ductwork. That’s really your best option.
Band aids would be making sure all the attic ductwork is properly sealed and insulated, and making sure you have sufficient intake (usually soffit) vents. You generally want slightly more total intake vent area compared to exhaust (ridge) vent area for optimal attic venting. If you have too little of either intake or exhaust venting, you can have moisture problems as well as an excessively hot attic.
Bill
Dan,
Bill is right. Start with applying mastic to all of the duct joints you can access in the attic. Then insulate them to R13 minimum, or fully condition and insulate the attic itself.
Your suggested solution involves air conditioning the whole neighborhood via your soffit vents..
https://www.buildingscience.com/documents/building-science-insights-newsletters/bsi-094-no-sweat