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Optional Accessories
Preheaters: Preheaters are standard as two-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 and the wheel
pressure drop sensor is triggered, 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.
See also Subassemblies/Electric Heaters
Post-heaters: Post-heaters are standard as
SCR control; see unit specific wiring diagram. 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.
Post-Heater Control Panel: The post-heater is
not single point wired to the RT control center.
Separate power must be supplied to the post-
heater disconnect (located in unit control center).
See Access Door Descriptions and Locations for
access to post-heater control panel. For Model RT,
the exhaust filters must be removed from the unit to
access.
Electric Heater Application/Operation
Factory installed electric heaters may be optionally
supplied for energy wheel preheating. The optional
electric preheater is positioned upstream of the air
intake filters and its primary function is to prevent
frost accumulation on the energy wheel. Electric
heaters are available in 208, 230, or 460 VAC (refer
to heater nameplate for voltage). An optional
tempering electric heater may be installed as a
supplementary heat source and is located as shown
in Subassemblies/Optional Electric Heat.
Service Outlet
120 VAC GFCI service outlet ships
loose for field installation. Requires
separate power source so power is
available when unit main disconnect is
turned off for servicing.
Vapor Tight Lights
Vapor tight lights provide light to each of the
compartments in the energy
recovery unit. The lights are wired
to a junction box mounted on the
outside of the unit. The switch to
turn the lights on is located in the
unit control center. The switch
requires a separate power source
to allow for power to the lights
when the unit main disconnect is
off for servicing.
Model RT Energy Recovery Unit
19
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