Thermolec Open coil heaters - Manual (Page 2)

1.2.12 Important Notes
• Do not install a duct heater in a vertical duct directly above a ceiling diffuser or an opening in the ceiling.
• Do not install standard heaters outdoors. Order a heater with weatherproof control box instead.
• Do not install spray humidifiers upstream of duct. Install it downstream instead.
• Do not cover the control box with thermal insulating materials.
• Use special air intake louvers of weatherproof construction for preheat duct heaters to avoid intake of water or snow
particles. Make sure that motorized damper blades are not blocked with snow or dirt. Inspect the dampers regularly to
ensure a suitable airflow.
2- Electrical Installation of THERMOLEC heaters.
2.1 Disconnect all power sources before opening the control box and working within.
2.2 Read the nameplate carefully and consult wiring diagram before starting to wire.
2.3 Supply wires:
Use only wires suitable for 75°C. Wires shall be sized according to the Canadian Electrical Code requirements.
All wires must be brought in through knock-outs.
2.4 Disconnecting means:
Install a disconnect switch close to the heater according to the code unless a disconnect switch is already built into
the heater.
2.5 Control circuit wiring: Use class 2 wiring for control circuit connections to the duct heater.
2.6 Magnetic contactors:
If magnetic contactors are mounted outside of the duct heater, use only contactors approved for:
• 250,000 operations when controlled by auto-reset thermal cut-out (A) and by other switching devices in series with
this cut-out (thermostat, step controller, air flow switch, etc.).
• 100,000 operations when controlled by auto-reset thermal cut-out (A) alone.
• 100,000 operations when controlled by auto-reset thermal cut-out (A) plus manual reset cut-out in series.(A&M).
• 6,000 operations when controlled by manual reset cut-out (M) alone.
2.7 External Controls ratings:
Rating of external control devices shall be suitable for handling the VA ratings as marked on the nameplate,
otherwise, a back-up relay must be used.
2.8 Air Flow Interlock:
Heaters are generally supplied with one extra terminal marked ( I) for fan interlock or air sensing device connection.
Remove jumper between terminals I and C before connecting the fan interlock, Select a suitable air flow sensing
device of the differential pressure sensing type, with snap acting contacts. A slow make, slow brake device may
cause undue cycling and in some instances chattering of the contactors. When fresh air dampers are used, make
sure the heater is properly interlocked to prevent it from being energized before the damper is fully open.
3- Operating THERMOLEC Heaters.
3.1 Minimum air flow.
Ensure that sufficient air flow as marked on the nameplate is passing through the heater. Air flow should be evenly
distributed across the entire face of the heater. Use air turning vane at duct elbows and splitter damper at duct
branch-offs to streamline the air flow in the heater. Use suitable air flow sensing device or interlock the heater with
fan. An insufficient air flow will lead to the opening of the auto-reset thermal cut-out or damage to the heating
elements.
3.2 Warning.
The air flowing through the duct where the heater is installed shall not contain any combustible particles, nor any
flammable vapor or gas.
3.3 Air Temperature.
The air temperature should not exceed 27°C (81°F) at the heater inlet and 66°C (151°F) at the outlet.