Greenheck Fan 90 optional accessories, Electric Heater Application/Operation, Electric Preheater

optional accessories

Electric Heater Application/Operation

Factory installed electric heaters can be provided for preheat and/or post-heat.. An electric preheater warms the outdoor air prior to the energy recovery wheel to prevent frosting on the wheel.. An electric post-heater warms the air leaving the energy recovery wheel to a user specified discharge temperature.. Electric heaters are available in 208, 230, or 460 Vac (refer to heater nameplate for voltage)..

Preheaters: Preheaters are standard as 2-stage, step control.. Step control heaters are designed with multiple stages made up of equal increments of heating capability.. For example, a 10 kW heater with two stages will be composed of two 5-kW stages.. Preheaters are single point wired at the factory.. A temperature sensor (with field adjustable set point) is mounted in the outdoor airstream after the preheater to turn the preheater on.. See Frost Control Application /Operation for typical set points.. If the temperature falls below the set point, the first stage of the preheater will turn on.. If the first stage does not satisfy the set point, the second stage will also turn on..

Post-heaters:Post-heaters are standard as SCR control.. Post-heaters are not single point wired (see Electrical Connections).. A temperature sensor (with field adjustable set point) is mounted in the outdoor airstream after the post-heater to turn the post-heater on.. A SCR heater provides an infinitely modulating control of the heat to provide an accurate discharge temperature.. A call for heat is required..

Electric Preheater

The preheater is single point wired to the HRE control center.. Access to the preheater control panel is through the supply filter door..

Post-Heater Control Panel

The post-heater is not single point wired to the HRE control center.. Separate power must be supplied to the post-heater disconnect (located in unit control center)..

Access to the post-heater control panel is through the exhaust filter door.. The indirect evaporative cooling media must be removed from the unit along with the exhaust filters to access..

Electric Post-Heater

17