5
JOHNSON CONTROLS
FORM 115.20-NOM6 (1106)
INSTALLATION
DUCTWORK
Ductwork recommendations are as follows:
•
Insulate to prevent condensation during
cooling.
•
Size to the unit openings are generally
acceptable but are determined by the engineering
drawings.
•
Be sure units are ducted per local codes or
national codes, as applicable.
WIRING
Units are provided with wiring diagrams and name-
plate data to provide information required for neces-
sary field wiring. All wiring must comply with local
and national code requirements.
Refer to Fig. 3 for access locations.
These units are provided with a class 2 transformer
for 24-volt control circuits. Should any add-on equip-
ment also have a class 2 transformer furnished, care
must be taken to prevent interconnecting outputs of
the two transformers by using a thermostat with isolat-
ing contacts. These units are supplied with a 3-speed
control board.
The YCW units
(2-pipe cooling) are provided as
standard 120 volt power wired to a disconnect/terminal
block and a ground lug. Fan motor hi, med and low
speed leads are wired to the control board. There may
be an unused motor lead from the motor – it needs to
be capped off. The board is also wired to handle either
24v or 120v control wiring. To use 24v, remove jump-
ers on the control board. To use a 24v chilled water
control valve, wire the valve in series with the “Y”
connection from the control box, max of 20va.
For 24v wiring using a T420 manual C/O, T421 auto
C/O or the T200 speed control thermostats, you will
need a 6-wire thermostat cable minimum.
The YCW-HW units
(4-pipe heating/cooling) are
provided as standard 120 volt power wired to a dis-
connect/terminal block and a ground lug. Fan motor
hi, med and low speed leads are wired to the control
board. There may be an unused motor lead from the
motor – its needs to be capped off. The board is also
wired to handle either 24v or 120v control wiring. To
use 24v, remove jumpers on the control board. For
your 24v hot water control valve, wire it in series
with the “W” connection. For your 24v chilled water
control valve, wire it in series with the “Y” connection.
For 24v wiring using a T420 manual C/O, T421 auto
C/O or the T200 speed control thermostats, you will
need a 7-wire thermostat cable minimum.
The YCWE units
(2-pipe cooling w/electric heat)
are provided as standard 208/240 volt power wired
to a disconnect switch with a ground lug. Fan motor
hi, med and low speed leads are wired to the control
board. There may be an unused motor lead from the
motor – its needs to be capped off. The board is also
wired to handle either 24v or 120v control wiring.
To use 24v, remove jumpers on the control board.
The transformer in the control box is 208/240v with
a common terminal, one for 208v and one for 240v.
Transformer is wired 240v from factory; for 208v ap-
plication, move the ORG wire on the transformer to
the 208v terminal. For your 24v chilled water control
valve, wire it in series with the “Y” connection. When
using a T420 manual C/O, T421 auto C/O or the T200
speed control thermostats, you will need a 7-wire
thermostat cable minimum.
See Table 2 for MCA and
MFS for each unit size/electric heat KW size.
Any devices such as fan switches or
thermostats that have been furnished
by the factory for field installation
must be wired in strict accordance with
the wiring diagram that is supplied
with the unit. Failure to do so could
result in damage or injury.
