Where is the right place to fit a room vent?

Remember that an appliance will always draw air from the easiest source, i.e. the vent. If it is fitted on the other side of the room from the appliance, the resulting air flow could cause discomfort - which will inevitably lead to the occupant blocking the vent.

Always position the vent as near as possible to the appliance (either at high or low level).

Rectangular vent employed with circular duct.

A mistake commonly made by some manufacturers is mismatching vents and ducts at the expense of free area. For example a 9" x 3" louvered vent employed with a 3" duct or a 9" x 6" louvered vent employed with a 5" duct may result in a free area loss of up to 50% depending upon the distance between the louvre and the duct and the restriction imposed.

Keep all ventilation components in proportion and keep changes in section to a minimum i.e. 6" sq. louvre employed with a 5" duct and ensure the duct neither butts nor terminates so close to the louvre that the effective free area is reduced to just that of the centre portion of the louvre.

The occupants say they feel snug and warm when the appliance is on - and they often nod off.

The appliance is doing its correct job by keeping them warm. But watch out, there could be insufficient fresh air supply if they are falling asleep. Remember a side effect of Carbon Monoxide poisoning is drowsiness.

Check that the vent is the right size for the appliance, is it being restricted in any way? Look for kitchen film or flyscreen on the vent, builder's rubble inside the cavity or debris such as leaves, cobwebs or even a vermin nest that could restrict the free area. If you then feel excessive cold air, use our retrofit cowl or redirect the internal louvres.

Why ventilate an appliance compartment?

Air must be provided to the appliance for combustion, flue operation and cooling. Insufficient air supply could result in the flue working incorrectly with the possible result of harmful gases seeping into the living space. Ventilation must be provided at high and low levels to create good circulation. The free area of the vents will be determined by: 1) Input of the appliance; 2) Balanced or open flue; 3) External or internal venting.

Airflow's technical help-line is always available to offer further assistance. Airflow's free area calculator is available on request.

Can appliance compartment vents and through wall vents be used together?
Compartments must be vented from the same source, both high and low vents must communicate either with the same room, which may also require ventilation, or with outside air at the same wall. These measures will ensure that flue spillage does not occur and that vitiation does not result at the top of the compartment.
When should I use a floor vent?
Floor vents are a discreet means of supplying air directly to the appliance reducing the possibility of draughts. However, the following points should be considered to ensure that the air supply is constant.
1. The vent is not sited in a position likely to be walked over which may close the louvres on some metal vents on the market, reducing the free area.

2. The air path below the floorboards is not blocked by insulation or rubble.

3. Sufficient air supply is provided to the underfloor space. Airbricks must conform to BS493 (1995) and BS5440 Pt2. Clay airbricks with apertures of less than 5mm and airbricks with flyscreens are not permitted as they may become easily blocked by debris.

If in doubt, replace with Airflow's AIR920 airbrick, details of which are to be found in our Rectangular Through Wall Catalogue.

Draught free ventilators

No such thing - unless the occupant blocks it up! An appliance will naturally pull outside air into a room - that's the whole purpose of a ventilator - and the cooler air will be felt by the occupant. Airflow products reduce these effects as much as possible without compromising safety by having cowls, integral baffles and internal directional louvres.

See product specifications detailed in the Draught Buster pages.

An Airbrick is an airbrick
Rubbish! Airbricks vary greatly in free air and more importantly their ability to comply with BS493 and BS5440 Pt.2. The Airflow airbrick has one of the highest free areas available on the market and complies fully to the regulations.
British Gas approve products
No they don't. In fact no ventilation product has been approved by British Gas within the last 25 years - they specify the use of products. As they do with ours.