Thermolec Application &Technical Notes - Manual (Page 65)

Specifications and Safety Features
Heating capacity of 1 to 8 KW.
Standard voltages 120, 208, 240, 277 and 347.
Standard round collar dimension 6" and 8" for easy installation between the floor joists
(or basement false ceiling). Other dimensions up to 12" diam. and 24"x18" duct also available.
Please contact factory.
The unit operates at low temperature (60ºC / 140ºF max.) and has three levels of protection:
• one automatic reset cut-out calibrated at (51.6ºC / 125ºF),
• one manual reset cut-out calibrated at (93ºC / 200ºF) and
• one airflow sensor that protects the unit against air failure.
This proportional sensor reduces the heating capacity if the air flow is not sufficient, so that
the discharge air temperature never exceeds 60ºC / 140ºF, and stops heating completely if
the airflow stops.
A THERMO-AIR or a THERMO-ZONE unit can modulate it’s heating capacity between 0 and
100 % according to the thermostat demand and/or the air flow going through the heater,
which makes this heater self regulating.
What is proportional control?
The word proportional refers to the portion of a time period in which a heating element is
turned ON and OFF (e.g. 10 % ON and 90 % OFF meaning 10 % of the heating capacity).
According to the thermostat demand, the heater is pulsed in different proportions of ON time
and OFF time to match the heating demand. The longer the element is turned ON, the more
it is generating heat and vice versa. The heat produced during the ON period continues to
dissipate during the OFF period, thus creating an average temperature output matching the
thermostat set-point.
For a graphic description of the proportional control, please see next page.
THERMO-AIR & THERMO-ZONE