I just got a brand new 88,000 btu heat/AC unit on my house. My downstairs is very cool but my upstairs (which has a vaulted ceiling) is very hot. I have one floor vent in my bedroom and all the vents in the upstairs are open. I have heard of a fan or blower that you can put into the floor vent that will help draw more cool air into my upstairs. Is this true and if so what are they called and who carries them.
Those are inline duct motors, and they sell those out of the grainger catalog, or any HVAC supply house or a service tech in your area may be able to get them and install them.
Other options would be to balance your system ie; close all downstairs vents 80 % and see if that makes a difference. Also, a fan on that vaulted ceiling may help circulate air.
What about your return air vents? Where are they? Do you have any on the second floor? Are they in the floor or up high?
If you are not drawing return air from the top of your second floor, it is unlikely that you will every be truly happy with the cooling upstairs, regardless of how you supply it (fans, etc)
Heat rises, and without proper returns to pull it down and back into the system, there will always be a large temperature difference between your first and second floors.
The best way to cool your upstairs and save money at the same time is with a whole house attic fan.
These fan can flush out the hot air that concentrates on the upper floors and in the vaulted ceilings.
During the day, if you have a basement, you can open the basement windows to pull in the cool air upstairs. If you don't have a basement, you can water the grass or shrubs outside a window and open that window to pull in cooler air.
At night you can open the upstairs windows and pull in the cooler evening air to displace the very warm air upstairs.
The whole house fan will also blow out the very hot air inside the attic and reduce the heat load onto the rooms below.
Noise concerns: most fans sold in the big box stores are poorly made and are consequently noisy.
Solution: a well engineered whole house fan runs quietly, even after many years.
See atticfan.com.
Insulation concerns: a 6 or 9 square foot of attic area is required for a properly sized fan and the insulation is removed. While a shutter fills this hole, some heat and warm air is lost to the attic in the winter. This is a small price to pay for the added comfort and reduced cooling costs in the summer. A simple piece of foamboard or foamcore, available at hobby and office supply stores can solve this problem. Attach the foam board with velcro to the ceiling shutter and end most of the heat and air loss.
I agree with magicman. The whole house fan is fine for spring or fall but in the heat of the summer doing what atticfanman suggests will only pull more humidity into the house and make your system work 10x more than it has to to remove the humidity from the house, making your problem much worse. You really need to have a good balance of supply and return air for comfort and energy savings, if this means adding to your current duct system, you might spend a little more but it will be worth it come mid July-Aug.
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