Filter
Top Products
4-10T-268-07
4.4.5 Heating (See Figure 4-4.)
The unit will heat only when the controller set point is
above --10_C(+14_F), or --5_C(+23_F) optiona lly, as
relay TH is electronically locked out to prevent heating
when the controller set point is below -- 1 0 _ C(+14_F),
or --5_C(+23_F) optiona lly.
If the air temperature decreases 0.5_C (0.9_F) below
controller set point, TH closes and the system enters the
heatingmodewhichis designedtoraisethecontainerair
temperature. When TH closes, power flows through TH
contacts and the heat termination thermostat to energize
the heat contactor (HR). This in turn energizes the
heaters and heat light. The evaporator fans continue to
run to circulate air throughout the container.
As the supply air decreases to the in-range tolerance
below set point, relay TI and the in-range light
de-energize (after a 15 minute time delay) and will
remain de-energized until the supply air increases to a
tolerance below set point. (Refer to section 3.1.4, Code
30.)
When the temperature rises to 0.2_C (0.4_F) below set
point, TH opens (heating off) and the system again
enters the holding zone. The compressor and condenser
fan motor are not running as contactors CH and CF
remain de-energized. The evaporator fans continue to
run to circulate air throughout the container.
A safety heater termination thermostat (HTT) attached
to an evaporator coil support, set to open at 54.5_C
(130_F), will open the heating circuit if overheating
occurs.