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.
