Looking at houses and offices in the UK, you might notice vents on certain walls. Depending on the duct system the vents are hooked up to, they will either supply air from or return air to the furnace. The wall vents are the decorative part of the heating and air conditioning system, much like outlet covers are to electrical sockets. To install wall vents, you must be comfortable working around a few hand and power tools.
Measure the opening in the wall that the wall vent will cover. Measure the width and the height. When sizing wall vents, the width is the first number mentioned. If you measured an opening 30 cm (12 inches) wide by 15 cm (6 inches) high, look for a vent labelled as a "12-by-6" model.
Determine if the vent will cover a supply air or return air duct opening. Turn the furnace on. If air blows out of the opening, it's a supply air duct opening. If air is sucked in, it's a return air duct opening.
Purchase the correct size and type of vent from your local home improvement store.
Look over your vent. You'll notice that the back side has a rectangular frame that will slide into the wall opening.
Slide the rectangular frame into the wall opening until the vent is flush with the wall. Screw one side into the wall. Position a level on top of the vent and adjust until it is level. Screw the other side into the wall. Use the screws that came with the vent.
Wear gloves when handling your wall vent. The metal edges are very sharp and can cause severe cuts.