Down Draughts; Ventilation And Combustion Air Requirements - EIRECO 740 Designed And Manufactured In Ireland

All register plates, restrictor plates, damper etc., which could obstruct the flue at a future date
should be removed before connecting this appliance.
If connecting to an existing chimney with a flue diameter of more than 250mm or 8 inches it is
essential to line the flue using a suitable stainless steel flue liner.

DOWN DRAUGHTS

However well designed constructed or positioned, the adequate performance of the flue can be
unfavourably affected by down draught caused by nearby obstructions such as hills, tall
buildings or trees. These can deflect wind and blow directly down the flue or create a zone of
low pressure over the terminal. A suitable anti-down draught terminal or cowl will usually
effectively combat direct down draught but no cowl is likely to prevent down draught due to a
low pressure zone.

VENTILATION AND COMBUSTION AIR REQUIREMENTS

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The minimum effective air requirement is 132 cm . When calculating combustion air
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requirements use the following equation: 550mm per each kW of rated output above 5 kW
should be provided; where a flue draught stabiliser is used the total free area shall be increased
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by 300mm for each kW of rated output.
If there is another appliance using air fitted in the same or adjacent room, it will be necessary
to provide an additional air supply.
All materials used in the manufacture of air vents should be such that the vent is dimensionally
stable, corrosion resistant, and no provision for closure.
The effective free area of any vent should be ascertained before installation. The effect of any
grills should be allowed for when determining the effective free area of any vent.
Air vents direct to the outside of the building should be located so that any air current
produced will not pass through normally occupied areas of the room. An air vent outside the
building should not be located less than the dimensions specified within the Building
Regulations and B.S. 8303: Part 1 from any part of any flue terminal. These air vents must also
be satisfactorily fire proofed as per Building Regulations and B.S. 8303: Part 1.
Air vents in internal walls should not communicate with bedrooms, bedsits, toilets, bathrooms
or rooms containing a shower. Air vents traversing cavity walls should include a continuous
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