EHK Installation Manual
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Specifications are subject to change without notice
3. Heater staging
The units are shipped circuited for single stage operation.
The heat can be staged either through an indoor thermo-
stat or by using an outdoor thermostat.
When two stages
are desired, cut W3 at the W2 wire nut, strip and recon-
nect per wiring staging layout in Installation Instructions
for fan coils.
a. The 5kW, 8kW, and 10kW heaters are single stage only.
b. The 9kW and 15kW heaters are adaptable for two
stage operation.
c. The 18kW, 20kW, 24kW, and 30kW heaters are adapt-
able for three stage operation.
4. Rectifier and Time Delay Boards
Each heater element is controlled by a relay mounted on
the heater panel. The relay has a 24V DC coil. Each relay
has a small rectifier board attached directly to relay coil
terminals. The rectifier board converts incoming 24V AC
control signal to DC. Some heaters may have up to three
relays. The second and/or third relay rectifier board also
has a time delay feature and a small jumper wire built into
it. With the jumper uncut, the time delay allows the second
stage heat to be energized approximately five (5) sec-
onds after the first stage. On 18kW, 24kW, and 30kW
heaters, the third stage relay board jumper is cut at facto-
ry. This provides an eight (8) second delay after first stage
relay closes.
Figure 4 Bezel Installation
A03069
Installation of Window Bezel for Circuit Breaker Model Heater
B. Power Connections
NOTE: Heater supply circuit wire size and overcurrent
protection must comply with National Electrical Code (NEC)
and UL branch circuit requirements. (See Table 3) Wires and
overcurrent protection, integral to the heater, are not required
to meet branch circuit requirements. Internal circuit protec-
tion of 60 amps (maximum) is acceptable.
1. Unprotected heaters: (See Figures 6, 10, and 11)
a. The 5kW through 10kW single phase and 15kW and
18kW three phase heaters can be wired for single supply
circuit only. Supply circuit connects to heater pigtail leads
(terminal block on 18kW heaters).
b. The 5kW through 10kW single phase heaters can use a
separate field−installed, factory−authorized disconnect
kit which installs in fan coil.
NOTE: Refer to wiring label for component locations.
c. The 9kW heater is factory wired for single supply circuit,
single phase. To convert heater to single supply circuit,
three phase:
(1.) Disconnect blue wire from limit switch (LS3). Cut,
strip, and connect to field wire L3.
(2.) Disconnect yellow wire from LS1 and connect to LS3.
(3.) Disconnect blue wire from relay 2, terminal 2 and con-
nect to LS1.
2. Circuit breaker heaters: (See Figures 7 and 9)
a. The 5kW through 10kW heaters can be wired for single−
supply circuit only.
b. The 15kW and 20kW heaters can be wired for dual−
supply circuits only.
3. Fused heaters: (See Figures 8, 12, 13, and 14)
a. The 15kW and 20kW heaters can be wired for single or
dual supply circuits. Single supply circuit wiring requires
a factory authorized, single−point adapter kit.
b. The 24kW and 30kW heaters can be wired for single or
multiple supply circuits. Heaters are factory wired for
single circuit three phase. To convert heaters to single cir-
cuit single phase, disconnect yellow lead from L3 and
connect to L1. Disconnect black lead from L3 and connect
to L2. To convert heaters to multiple supply circuit single
phase, remove and discard leads between single circuit
terminal block and fuse block. Remove and discard single
circuit terminal block. Attach L1 through L6 power leads
as indicated on label next to fuse block.
C. Ground Connections
ELECTRICAL SHOCK.
Failure to follow this warning could result in
property damage and/or death.
According to NEC, ANSI/NFPA 70, and local codes,
cabinet must have an uninterrupted or unbroken
ground to minimize personal injury if an electrical
fault should occur. The ground may consist of
electrical wire or metal conduit when installed in
accordance with existing electrical codes. (See
Ground/Conduit Note below.)
!
WARNING
NOTE: Use UL−listed conduit and conduit connector for con-
necting supply wire(s) to unit to obtain proper grounding. If
conduit connection uses reducing washers, a separate
ground wire must be used. Grounding may also be accom-
plished by using grounding lugs provided in control box.
1. For unprotected or single circuit heaters, 1 equipment
ground connection is provided on fan coil unit. (See Figure
1 or 2)
2. For 15kW and 20kW circuit breaker heaters, an addition-
al ground lug is provided on circuit breaker mounting brack-
et for dual circuit grounding. (See Figure 3)
3. For 15kW and 20kW fused heaters, an additional ground
lug is provided on fuse mounting bracket for dual circuit
grounding. (See Figure 2)
4. For 24kW and 30kW fused heaters, two (2) additional
ground lugs are provided for single phase, multi circuit wir-
ing. (See Figure 1)