Central A/C Vents and Cold Air Return Covers
jimmiem
| Posted in General Discussion on
I have central a/c in my 2 story house with ceiling vents and cold air return. I am going to build some covers to block the winter drafts. I’ll construct the frames from wood or PVC. I was going to make the frame inserts from plexiglass but I came across large sheets of corrugated plastic at HD and Lowes. Anybody ever use these for anything like this? Much cheaper than plexiglass. The vents are 14″ X 14″ and the cold air return is 26″ X 38″. The cold air return is flat so that will be easy. The vents are 2″ or 3″ thick so will require so angle cuts due to their design.
Replies
How are you planning to secure these covers to the ceiling?
And what do you mean by "corrugated plastic"? I'm thinking the plastic sign board that you would cut with a knife and join with tape.
The ceiling vents and cold air return are not metal so magnets won't work. The cold air return is flat and has some pedrilled holes around the rim so I'll probably use sheet metal screws. The vents aren't flat...I had seen some commercially available covers which are held in place by a cord that is attached to the center of the vent and runs through a hole in the center of the cover and has a spring clip to hold it tight......I may borrow that design.
The corrugated plastic is with the plexiglass in HD and Lowes. It has 2 thin white plastic faces and a corrugated center....advertised for packaging and sign making. I had never seen the stuff until today....it is very light and not too expensive ($15.00 for a 36" X 72" sheet).
Have you thought about just unscrewing the covers, covering in oversized plastic, screw them back in place and then trim the plastic back with a utility knife??? (gently so as not to cut the drywall)
No muss No fuss little to no cost and virtually invisible and nothing to build.....and you could clean the vents while they are off which your wife would likely appreciate and paint them if need be.
The way these are constructed it would not be easy to do that. The frame is screwed in and the grates are accordioned....best way I can describe it and are held in with springs that are compressed and pushed into the hold holes. Lousy explanation but I don't think they would stand up to being taken off/on. I juist tried to remove one and a tack weld holding a bracket came apart.
Maybe you should simply replace the vent covers with ones that have an on/off control.
They do have a lever that I can just about reach with my finger that opens and closes the louvers. I open and close them, depending on the season, but they are not air tight. The louvers are metal. Maybe I'll look into changing them out. Hopefully they'll be a standard size but knowing the guy who did the original install I'm doubting it. The cold air return filter is an odd size and I've had to pack foam around the edges to hold it in place.....finally bought the filter that you cut to size.
BTW, this is how my whole house fan is sealed each year...take the frame down, clean the frame, drape plastic over it when you put it back up and cut the plastic back to the frame....and I tell the wife
"Don't say I never clean anything"
Reminds me that I need to put the cover back on our ceiling fan. There is a box around the fan made from old corrugated plastic lawn signs, and a cover for the top of the box made from the same stuff. In the spring we just let the fan blow the cover off, so I only need to go up each fall and slide it back into place.
I don't understand. Where is the cold air comming from? If the a/c is not on, how is cold air comming out of the registers? Is the duct work connect to or open to the outside?
The theory is that warm household air rises up into the vents and cold air return, then it cools down and comes back into the house. I close off the vent grates but they are not air tight.
A non-operating duct system will definitely set up its own convective air flow especially if it is a high register - low register set up or if it is a multistory set up....now the air cirulating through the system SHOULD all be room temp indoor air that is only cooling to the extent the duct work cools it down....the problem is that ducts often leak and cold air ducts often are built on boxed in stud bays and/or boxed in joist runs....the cold air returns in those cases can often find outside air and draw it into the loop....
My cold air return in a 1996 house has a cold air return that uses the stud bay between the first and second floors and a galvanized covered joist bay as well....well stud walls also have electrical and plumbing running through them often horizontally.
In my case my cold air return found a path through the stud bay across a wall to the exterior wall such that every time the furnace ran it was sucking in outside air so much so that it froze water pipes in the middle of my basement.
So yes, in theory you aren't really feeling cold air just moving air but it does create a current of air in the house and it COULD be outside air that is significantly colder than the indoor air.
I found a 4 mil roll of poly so before spending a lot of time building frames and attaching corrugated plastic I'll use the poly. The cold air return 'door' opens on a hinge....I'll just open it, lay the poly on it, and close it to hold the poly in place. I'll just tape the poly over the a/c vents....won't be pretty and if my wife doesn't complain I'm done with it....if she does complain I'll make the 'pretty' frames.