Sequence of Operation - Electric Heater
1.Electric heaters are divided in to equally sized steps. For example, a 60 kW heater with 3 steps will have 20 kW per step. The thermostat and step controller will control these steps.
2.120 Volt power from the control center (when supplied) or by others with out a control center, is delivered to the electric heater for the step controller. This power must be interlocked with the supply fan, so when the fan is off, the heater control power is off.
3.A step control with the thermostat set to 70ºF the heater will be off with a temperature sensing above 70ºF. As the temperature varies the steps turn on and off to hold the setpoint discharge temperature. The colder the discharge temperature becomes the more steps the controller will energize.
4.With a step controller, in addition to the fan interlock mentioned in Step 2, the heater has an airflow switch to prove that airflow is established before energizing the steps. The heater also has an automatic resetting highlimit switch and manual resetting highlimit switch set above the automatic switch to protect from overheating.
5.For more detailed information on your specific controller, please review the controller spec sheet supplied with the heater.
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Model MSCF Modular Small Cabinet Fan 15