Thermostat User Manual
2-4 l Description
How it Works
The HTC process air heater works a lot like the thermostat and heater in your
house. The RTD probe measures the temperature of the air entering the hopper.
If this air is not warm enough to properly dry the material in the hopper, the
RTD sends a message to the temperature controller which tells the heater to
begin heating. The heating elements inside the heater enclosure heat until the
RTD probe senses that the air entering the hopper is at the setpoint entered by
the user.
The HTC has a process protection RTD (over-temperature safety). The temper-
ature controller shuts off power to the heating elements if they get too hot and
an alarm is generated.
An air flow differential pressure switch detects air flow by sensing the natural
drop of pressure due to flow through the heater. This prevents damage to the
heater elements or material in the hopper on loss of air flow.
The temperature controller alarms if the heating elements are heating too hot. It
also alarms if the heating elements are not heating enough.
How the HTC Works
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H
eaters
S
tartup /
Shutdown
For Startup:
1. With heaters in
Standby, turn on
blower or dryer.
2. Enable heaters.
For Shutdown:
1
. Switch heaters to
Standby.
2
. Wait 60 seconds
before turning off
blower or dryer.
Enable
Standby
Temperature Controller
Control Center
Hopper Inlet
Heater Box
Heating Element
Process Temperature RTD
Process Protection RTD