The automatic reset thermal cut-out is a fixed temperature disc type safety device that opens the control circuit when it’s set point is reached. It automatically resets and returns the heater to operating conditions when the overheating conditions have disappeared.

It offers additional protection against overheating. It is standard on heaters of 30 KW and less and not in excess of 300 volts, and optional on all others. This switch must be manually reset to make the heater operational.

A built-in control transformer is required on most heaters to supply 24 volts to the control circuits. A Class II transformer has built-in safety protection and does not require primary fusing. Primary and secondary fuses can be supplied upon request.

Magnetic contactors are used for stage switching and/or back-up for safety devices. Approved for 250,000 cycles. Magnetic contactors are cost effective and safe.

Used to protect the total load or individual stages. High Rupture Capacity type (HRC Form 1).

A built-in disconnect switch allows heaters to disconnect individually in order to perform maintenance tasks. It is a positive and inexpensive way to meet the safety rules. It also reduces the electrical installation costs because the disconnect switch is factory installed. Thermolec strongly recommends that a built-in disconnect switch be specified at all times.

Safety feature, monitors the quantity of air flowing through the heater, adjusts the heater’s capacity to match the air flow available and shuts the heater down in case of a total loss of air. This feature is available only on heaters equipped with full SCR.

A pressure differential switch is used to prevent a heater from operating if there is no airflow across the heating elements. The switch is provided with a pitot tube to be installed into the duct, which makes it sensitive to velocity pressure as well as to static pressure. In applications where there is not enough pressure to activate a differential pressure switch, an electronic air flow sensor ...

Mercury contactors are used for stage switching. Advantages: silent operation. Exceptionally reliable. Long life expectancy (Tested for 1,000,000 cycles) Note: Mercury contactors are position sensitive, hence it is important to specify in which position the heater is to be installed.

Pilot lights are mounted on the control box to indicate that either a function of the heater is operating or a failure condition is present. The most commonly specified pilot lights functions are: power on, heating on, no airflow, overheating, stages on. The pilot lights' functions must be specified when ordering.

Solid State Relays are designed for controlling, silently and proportionally, a large amount of power in response to a pulsed signal (suitable for DDC, Direct Digital Control). They incorporate a dual SCR (Silicon Controlled Rectifier) to provide full-wave capability and Zero Crossing Drive Circuitry. The opto-coupler provides the interface to the logic level input signal and electrical input-to-o...

The D21-P electronic controller has been designed to take full advantage of our patented Air-Flow Sensor which modulates the heater’s capacity according to the quantity of air flowing through the heater by responding to the radiant heat of the elements even at very low CFMs. With normal airflow the controller will operate at full power. When the airflow drops below the minimum airflow, the control...

The D22-P electronic controller has been designed to take full advantage of our patented Air-Flow Sensor which modulates the heater’s capacity according to the quantity of air flowing through the heater by responding to the radiant heat of the elements even at very low CFMs. With normal airflow the controller will operate at full power. When the airflow drops below the minimum airflow, the control...

The D21-PS electronic controller has been designed to take full advantage of our patented Air-Flow Sensor which modulates the heater’s capacity according to the quantity of air flowing through the heater by responding to the radiant heat of the elements even at very low CFMs. With normal airflow the controller will operate at full power. When the airflow drops below the minimum airflow, the contro...

The D21-PSSR electronic controller has been designed to be a compact solution to take full advantage of our patented Air-Flow Sensor which modulates the heater’s capacity according to the quantity of air flowing through the heater by responding to the radiant heat of the elements even at very low CFMs. With normal airflow the controller will operate at full power. When the airflow drops below the ...

The D21-T electronic controller has been designed to take full advantage of our patented Air-Flow Sensor which modulates the heater’s capacity according to the quantity of air flowing through the heater by responding to the radiant heat of the elements even at very low CFMs. With normal airflow the controller will operate at full power. When the airflow drops below the minimum airflow, the control...

The D22-T electronic controller has been designed to take full advantage of our patented Air-Flow Sensor which modulates the heater’s capacity according to the quantity of air flowing through the heater by responding to the radiant heat of the elements even at very low CFMs. With normal airflow the controller will operate at full power. When the airflow drops below the minimum airflow, the control...

The D21-TS electronic controller has been designed to take full advantage of our patented Air-Flow Sensor which modulates the heater’s capacity according to the quantity of air flowing through the heater by responding to the radiant heat of the elements even at very low CFMs. With normal airflow the controller will operate at full power. When the airflow drops below the minimum airflow, the contro...

The D21-TSSR electronic controller has been designed to be a compact solution that takes full advantage of our patented Air-Flow Sensor which modulates the heater’s capacity according to the quantity of air flowing through the heater by responding to the radiant heat of the elements even at very low CFMs. With normal airflow the controller will operate at full power. When the airflow drops below t...

The D35 pre-calibrated electronic controller is Thermolec’s most flexible controller with four different input options on a single board. Jumper configurations are clearly indicated on the label and may be changed at any time. Control signals supported are Thermistor for Thermolec’s RT, DT or RADS, 0-135 Ohms, 4-20 mA and 0 - 10 VDC. Since the D35 is not compatible with our Air Flow Sensor it is r...

Hybrid sequential Step Controller The D46 hybrid sequential step controller is designed to be used where fine control accuracy is required and the heater capacity is too high to be handled economically by "FULL SCR". With a combination of a smaller SCR and a step controller, both being controlled by the same input signal the SCR stage automatically fills the gaps between the step controlled stage...

Pneumatic-electronic transducer. The P37 is a Pneumatic-electronic transducer that converts a 2-13 psi input into a proportional Pulse or 0-10VDC output and therefore replaces both the P35 and P36. For ease of use the board is programmed for 3-8 psi Pulse output selectable from the MODE DIP SWITCHES in Direct or Reverse Acting mode. Custom pressure ranges can be adjusted in the field with qualifi...

Electronic Sequencer The TH34 electronic sequencer has been designed as a compact solution to replace bimetallic mechanical sequencers to split loads into smaller delayed sequences. When the thermostat contact closes, Q1 is instantly activated and then Q2 to Q4 after approximately 20 seconds per sequence (timing may change without notice). This controller is ideal for residential installations to...

0-10 VDC Thermostat This thermostat can be used as a room stat or a duct stat with the optional DS600 sensor.

This thermostat can be used as a 1 or 2-stage duct stat with the DS600 sensor.

Duct sensor The DS-600 is a thermistor based duct sensor designed to work with Thermolec’s thermostats and electronic controllers to modulate the heater’s capacity according to the heat required. In most cases the DS-600 is used with Thermolec’s 0-10 VDC Room Thermostat to allow it to function as a duct stat. It can also be used as a remote duct sensor with our ‘T’ versions of controllers such as...

AcuSteam High Limit cutoff Thermolec’s exclusive ACE SENSOR monitors the conditions in the duct to prevent excessive buildup of humidity. It is included with every AcuSteam Pro and may be used with the residential AcuSteam as an option. The high limit cutoff is adjustable from 80 to 90% RH.