COMBAT CTU-90 - SECTION 9: Optional Heater Configurations; Distribution Duct Work for CTUB, CTUC and CTUD Heaters; Figure 9: Ducting

SECTION 9: OPTIONAL HEATER CONFIGURATIONS
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SECTION 9: OPTIONAL HEATER CONFIGURATIONS
9.1.1 CTUD Heaters
For CTUD heaters, it is essential that the airflow in
the duct system is at least that specified in the Data
Sheet on Page 9, Section 5.2 and in the correct
direction across the heat exchanger as indicated by
t
he arrow on the heater. Higher air flows are
permitted, but will cause a lower exiting air
temperature. It is recommended that the fan is
positioned to blow the air through the heat
exchanger.
The duct
must be designed as described on Page
17, Section 9.1 and Figure 9 to ensur
e that there is a
homogenous a
ir flow across the whole of the heat
exchanger.
Failure
to provide a suitable air flow properly
distributed across the heat exchanger will reduce the
life of the heat exchanger.
The fan motor, or its control, mus
t contain a method
of overload protection. When installed remote from
the heater, the fan must be supplied via a local
electrical isolator positioned and properly labeled to
prevent inadvertent operation.
9.1 Distribution Duct Work for CTUB, CTUC and
CTUD Heaters
CTUC heaters have the fans enclosed so that the
heater may be connected to inlet ducting.
CTUD heaters are supplied with inlet and outlet duct
spigots for mounting the heater into a customer
designed duct system for use with an external fan
system.
It is recommended that flexible duct connectors are
used to reduce duct born noises.
When installing CTUD heaters onto ducting force
the fan to run.
Do not rely on the fan thermostat to turn it on.
Any such device must be in parallel with the fan
thermostat so that the fan run-on operation will still
operate.
Contact Combat HVAC Ltd. Design Department
for recommendations regarding duct resistance
and design. Tel: +44 (0) 121 506 7700
Figure 9: Ducting
Ducting
Dimension
X
Minimum-
Twice
Dimension
X
Minimum-
Twice
Dimension
X
Airflow Indicator
Flexible Flange
Ducting
NOTE: Duct size will be full size of inlet and outlet.
All joints between the heater and duct work should be
made as air tight as possible.