Air Vent Leading to Attic

I have a huge AC bill over the summer - large house and I live in Orlando, FL. I have been looking at various tips here on this site and trying to get the bill down and this has prompted a question about my setup.

I have a large open space from the first floor to the second where my stairs are. At the top of this space is a vent in the ceiling. It leads straight up into the attic and is fully open to the attic. It does not have a lever on it to shut and open the vent. So, it looks to me that it simply allows air to move up into the attic from the ceiling area.

I would think that this would be a way to lose a lot of cold air and allow hot attic air into the house. SO.... I pulled it down, covered it with aluminum tape, and replaced it so that it is now closed off. Was this a mistake?? Is it common to have this soft of open air vent leading into the attic?

Any input would be greatly appreciated.

 

Hi ted and welcome to the forum.
I agree with you, it sounds strange. One of the objectives for improving the energy efficiency is to eliminate all air leaks from the house into the attic.

Was there a prior use for that opening, like a whole house fan? In some cases they install a large attic fan blowing air out of the attic and then install a powered louver between the house and the attic. Do you have an exhaust fan in the attic?

Does your ac unit, I assume it is in the attic, have a return duct that is pulling air from inside the house. The supply side delivers the cold air, but that volume needs to be matched by a return duct with the same amount of air.

Is the attic ventilated to the outside, soffit, ridge, gable or other vents?

Bud

 

I don't believe there was a prior use for that vent. We are the 2nd owner of this home and I don't think that the 1st owner cared much about such things, and I certainly couldn't see him installing or uninstalling anything.

The AC unit is inside the house, in a closet just to the right of this space I am describing. There are air returns in a number of rooms including a large vent just under the AC unit itself.

There is not an exhaust fan in the attic. The attic is ventilated to the outside via the soffits only. I have put a thermometer up in the attic and monitored the temperature. I don't recall off hand what it was, but I remember looking it up at the time and I was well within the range that was suggested - not too hot. I have sprayed thermal barrier on the underside of the roof plywood (I doubt that does much good, frankly).

This same house design appears down the street from me. I am going to go down to ask the home owner if I can see if they have the same vent. It just doesn't seem like it should be open.

THANKS!

 

What is that "thermal barrier", insulation or a radiant paint?
The attic may not be getting excessively hot because you are sharing your ac with it.

For your to-do list, consider gable vents or a ridge vent, a high vent location that is approved in FL.

As long as that opening was/is not part of the ac system, like a jump from one room to another or from one return duct to another, then closing it off, air sealing around it, and covering it with lots of insulation is correct.

With that opening now closed off, test all of your supply and return vents to be sure they are all moving air.

Bud

 

I am on it and will check back.

It was radiant paint. And it was horrible to spray up there. I did spend a fair amount of time in the attic and I don't think the system is venting into the attic.