COMBAT® CTCU UNIT HEATERS INSTALLATION OPERATION AND SERVICE MANUAL
SECTION 8: AIR SUPPLY
8.1 Room Sealed Installation
When installed as a room sealed heater, the air for combustion is drawn in from outside the building. It is important to ensure that there is adequate ventilation to provide air for the distribution fan/s.
8.2 Open Flued Installation
It is important to ensure that there is adequate air supply at all times for both combustion and heating requirements in accordance with local and national codes. When installed in this mode, the air supply to the heater must also be fitted with a low resistance terminal to prevent the ingress of debris. See Page 14, Figure 8.
8.2.1 Heaters Installed Within the Heated Space
Where the volume of the heated space is greater than 4.7 m3 per kilowatt of total rated heat input and the air change rate is at least 0.5/h, additional high and low level ventilation will not be required.
For a building having an air change rate less than 0.5/h, ventilation will be necessary in accordance with local and national codes. Ventilation direct to outside must be provided as follows:
•Heaters up to 70 kW heat input: 5.0 cm2 per kW of rated heat input
8.3 Building Ventilation
Where ventilation is required, air must be taken from an outside point where it is not likely to be contaminated or obstructed.
Where natural ventilation is used, suitable ventilation with outside air at low level must be provided in accordance with Section 8.2.1 and local and national codes.
Where mechanical ventilation is used, extract rate must be 5% - 10% less than the inlet rate. The mechanical ventilation must be interlocked with the burner on the heater.
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