Hubbard Air Transfer Unit

Ducting

The standard mounting arrangement is to an outside facing wall but if this is not available the unit can be ducted to an external air inlet using the bottom entry spigot. Good quality 150 mm circular rigid steel ducting and fittings should be used. All joints must be sealed.The increase pressure resistance on the fan should not exceed 130 pascals. This would nosily allow up to 10 m of straight ducting plus 4 x 90 degree bends. (150 mm circular duct resistance 7 pascals per metre, 90 degree bend 15 pascals, 45 degree bend 7.5 pascals.) Air flow of the unit will be reduced by 5 – 16% dependent on the total equivalent length of ducting used.