Winter HVAC Hack

Block winter drafts from home air conditioning vents: fast and low-cost.

For years I've been trying different schemes to block the cold drafts from my home's  Air Conditioning vents. They are essentially holes right into the unheated attic immediately above since this is a 1950s ranch-style house.

Because the vents are aluminum I can not use a standard magnetic cover.

The vent screws just go into drywall, so loosening or removing them every Winter will not work. The drywall ceiling just gets messed up.

This year I made covers from white two-ply corrugated plastic. I used Coroplast from old election signs and commercial road spam advertising signs.

Careful now, Mr. Potato Head - don't trespass, or take down signs before an election. In my area, commercial advertising signs on state roads are illegal and so are fair game.

You can also visit a sign shop and ask for rejected signs. Believe me, they have them and will give them away free of charge.

Rubber foam weatherstripping or Mortite caulking cord and a velcro strap save the day. My only innovation is making the cover by plastic welding two-ply Coroplast.

Here's the snug and warm finished vent cover.

Totally good to go with the whole Wife Acceptance Factor thing too, amazing, isn't it?

Held on with a 4 inches velcro strap and insulated with low-cost foam weatherstripping.

Read on to see how easy it is to do this...

Loop your double sided velcro strap through the vent louver.

Pass the free end through the hole in the end of the strap.

Tighten it up and turn the strap so it is close to the center of the vent.

Now you are ready to prepare your cover.

Measure the vent to the nearest half inch (centimeter).

In my house, the vents are 13 inches by 13 inches, and 9 inches by 9 inches.

Cut two corrugated plastic squares for each vent. Use a craft knife, tin snips, shears, or even scissors.

If your vents are rectangular, be sure that one piece of corroplast has its ridges running at right angles to the first. This gives extra strength, like plywood.

Using a hot soldering iron or soldering gun, poke through the top three layers to weld the two pieces of corrugated plastic together. Make sure the plastic ridges run at right angles to each other for strength.

Do this outside, or in a well-ventilated area. i use a fan and an open basement window because the smoke is pretty foul and is likely to contain all kinds of nasty stuff.

Wear appropriate safety gear - no fooling, a gob of hot plastic in the eye is just not a good thing. When working with a hot iron, i usually have a small tub of ice handy to instantly cool any finger burns.

I like to use my cheap hollow punch set to make a nice round half inch ( 1 cm )  near the center of the plastic cover.

You can also melt a hole with the soldering iron, or cut a hole with a craft knife.

I usually put the hole about half an inch off center towards the middle of one side to allow for adjustments.

This is because the velcro strap is never exactly centered on the vent.

I like soft squishy rubber weatherstripping foam.

You might also be able to use Mortite caulking cord, or recycled foam rubber.

Attach the adhesive-backed weatherstrip around the edge of the cover.

Now you see why the center cover hole is so large.

I use needle nose pliers to pull the strap through the cover hole.

You might be able to use wire or string and have a smaller hole, but this is easiest for me.

Attach self-adhesive Velcro fuzzy loop squares to the surface of the vent cover.

This will be where the Velcro Strap attaches to the cover.

Use a wadded up piece of foam to plug the hole in the cover.

Be sure it will be under the Velcro strap when it is pulled tight and stuck to the cover.

You have stopped the draft.

You might be tempted to use white vinyl tape or duct tape to seal off the corrugated openings in the sides of the covers. But in my experience this really does not make any difference

Not only can I set my thermostat lower, but the furnace seems to run a lot less now that these major draft sources are sealed.