The DR21 Anti-Draught Air Vent uses a 4”, 100mm hole which does not have to be drilled straight through a wall. A pilot hole can be drilled and then drill from each side. This has the advantages that a 100mm hole takes far less time to drill than a 127mm hole and puts less stain on the drill itself. It also means that if the wall is damp and the core drill is snagging, it can be drilled half way through from each side, which also means that you avoid the risk of flaking off the surface of the bricks if you drill inside out, and the plaster if you drill outside in.
- The vent has the same fixing holes as a standard louvred vent, so retro fitting one takes minutes, and it accepts all the standard tubes, ducting etc.
- It has a free air equivalent of 3400 sq mm, OK for a stove up to just under 12kw (if you include leakage 12 kw is fine) which covers most stoves fitted.
- It has been independently tested by Bre, and is approved by HETAS.
- It is patent protected and produced to ISA 9000:2015 standards entirely in the UK.
- It can be fitted over an existing 100mm hole, a 127mm hole or a 9” air brick.
- It cannot be used on a kitchen extractor fan and the fat in the air will rapidly clog the interior.
- It can be used for stoves up to 12kw, one could use two for larger stoves.
- It can replace the rattling bathroom vents, passive air vents and underfloor air bricks.
People use two for gas, they really should use three but as the old vent was almost certainly blocked with duct tape any ventilation is better than none.
A gas fire, or an open fire, is said to need 10,000 sq mm, and, although a 127mm hole is 10,000 sq mm in area, but the time you fit the baffle device it comes down to 7800 sq mm Free Air. Stadiums Black Hole Vent with the zig zag baffles within the 127mm diameter hole through the wall has a Free Air Equivalent of 2200 sq mm.