COMBAT CUHA - Building Ventilation; Distribution Ductwork CUHC and CUHD Heaters

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UNIT HEATER
For buildings with a design air change rate 0.5/h or greater and where the volume of the heated space
is greater than 4.7 m
3
per kilowatt of total rated heat input, as appropriate, additional high and low level
ventilation will not be required.
Where natural ventilation is used for compartment/plant rooms, suitable permanent openings at low
and high level, communicating directly with the outside air, must be provided.
Where mechanical ventilation is used, it must be by mechanical inlet and with either natural or
mechanical extraction. Systems of ventilation employing mechanical extraction and natural air inlet
must not be used.
Automatic means, such as interlocks, must be provided for installations where equipment failures can
lead to hazardous situations developing.
3.6 Building Ventilation
Air must be taken from an outside point where it is not likely to be contaminated, for example with
smells, road vehicle exhausts, dry cleaners exhausts, solvents etc.
The minimum quantity of outside air required for ventilation must be at least that required for personnel
within the building.
Where the heaters are located in the heated space the air supply requirement is not necessarily the sum
of the individual requirements for combustion, ventilation and dilution air, and fresh air, but the greater
individual requirement.
Where there are any open flued appliances in the room and where outside air is supplied mechanically
and there is mechanical extraction, the design extract rate must be 5% to 10% less than the design inlet
rate so that the room will be at a higher pressure than outside air.
3.7 Distribution Ductwork CUHC and CUHD Heaters
CUHD range heaters are supplied with inlet and outlet duct spigots for mounting the heater into a
customer designed duct system .
CUHB range heaters may be supplied to special request with the outlet flanged for connecting to
customer designed duct systems.
CUHC range heaters are as CUHB range but with the fans enclosed so that the heater may be connected
to inlet ducting.
It is important when ducted systems are required that only the flanges made and fitted at the factory are
used at the heater to ensure that the integrity of combustion zone and draught diverter is not impaired.
Also it isimportant that the lower front and rear panels remain accessible for burner routine maintenance
and repairs. The burner may only be removed from the front lower panel and the rear lower panel
needs to be removed to do this.
Provision should be made so that the complete heater may be removed from the duct system.