3. Heater staging
The units are shipped circuited for single-stage operation. Use outdoor thermostat kit Part No. KHAOT0301FST for 2-stage operation. Use
both kit Part No. KHAOT0201SEC and KHAOT0301FST for 3-stage operation. When 2-stages are desired, cut W3 at the W2 wire nut,
strip and reconnect per wiring staging layout in Installation Instructions for fan coils.
a. The 3-, 5-, 8-, and 10-kw heaters are single stage only.
b. The 9- and 15-kw heaters are adaptable for 2-stage operation.
c. The 18-, 20-, 24-, and 30-kw heaters are adaptable for 3-stage operation.
4. Intelligent Heat Staging
40FK, FK4, and FV4 Fan Coils are capable of Intelligent Heat Staging when installed with capable electric heaters (See Table 1) and a
corporate 2-speed programmable thermostat (TSTATXXP2S01-B), Thermidistat™ Control (TSTATXXPRH01-B), or Comfort Zone
II/Zone Perfect Plus. Consult the fan coil Installation and Set-up Instructions for wiring details. Do not install with outdoor thermostats when
installing for Intelligent Heat Staging.
5. 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 5 sec after the first stage. On 18, 24, and 30kw
heaters, the third stage relay board jumper is cut at factory. This provides an 8 sec delay after first stage relay closes.
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, 4, and 5.) Wires and overcurrent protection, integral to the heater, are not required to meet branch circuit requirements.
Internal circuit protection of 60 amps (maximum) is acceptable.
1. Unprotected heaters: (See Fig. 6, 10, and 11.)
a. The 5- through 10-kw single-phase and 15- and 18-kw 3-phase heaters can be wired for single-supply circuit only. Supply circuit
connects to heater pigtail leads (terminal block on 18-kw heaters).
b. The 3- through 10-kw 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 9-kw heater is factory wired for single supply circuit, single phase. To convert heater to single supply circuit, 3 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 connect to LS1.
2. Circuit breaker heaters: (See Fig. 7 and 9.)
a. The 3- through 10-kw heaters can be wired for single-supply circuit only.
b. The 15- and 20-kw heaters can be wired for dual-supply circuits only.
Fig. 5—Connection of Transformer
A94067
230
C
208
BRN
RED
YEL
BLK
SECONDARY
PRIMARY
—6—
