Thermon HELLFIRE 400, Installation, Operation & Maintenance Instructions Manual

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E.20 Terminal Blocks
1. The controller interconnects with the control panel
by means of 2 board level headers, TB-1 and TB-2,
which accept wire harness plug connectors.
2. The controller and EMS module connect via a ribbon
cable that plugs into the 10-pin header found on each.
The ambient temperature sensor connects via the
RJ11 header.
Table 1 – Terminal Blocks
Name Description
TB-1 Precipitation detector 24Vac power supply
TB-2 Precipitation detector
JP1 Ambient air temperature sensor RJ11 header
10-Pin
header*
EMS power and signal connection
* Located in the upper left corner.
E.21 Inputs and Outputs
1. PRECIPITATION DETECTOR: As its name implies, it
senses precipitation that can be in the form of rain
or snow.
Snow landing on the detector’s heated sensing head
melts to form water drops. The 360° sensing surfaces
detect blowing snow detect blowing snow as well as
falling snow.
See the installation section for mounting instructions.
There are no adjustments on the detector itself.
Sensitivity adjustments are made on the controller.
2. AMBIENT TEMPERATURE SENSOR : The ambient
temperature sensor is mounted beneath the air
intake hood. The controller compares the measured
temperature to the SNOW-RAIN and the LOW TEMP
set point.
3. RAIL THERMOSTAT : The rail thermostat optimizes
fuel consumption and performance while the heater
is requested. It functions independently of the
EMS module, cycling the heater off when the rail
temperatures rises above 9°C (49°F) then back on
again once the temperature drops below 3°C (37°F).