Cooling, Optional Equipment, Furnace Control Fuse

58HDV

For two-stagethermostat installations, the R, W1 and W2 wires from the thermostat connect to the R, W1 and W2 connections on the furnace control board. Set TT SW1 DIP switch #3 to ON position. During operation, the furnace will shift from Low Heat to High Heat as requested by the thermostat. (See Fig. 40 and wiring diagram)

Heat anticipator setting will need to be measured if 24VAC humidifier is installed. Measure current in series from R to W1 at the thermostat. Be sure 24VAC humidifier is operating during this check. Allow furnace to operate for 2 minutes before recording the AC amperage reading. Set anticipator on thermostat to recorded value.

Thermostat location has an important effect on the operation of the furnace. Follow instructions included with thermostat for correct mounting and wiring.

Low voltage connections to furnace must be made on terminal board to furnace control board. (See Fig. 41)

Cooling

If single-speed cooling is used, the Y and G from the thermostat must be connected to the control board Y/Y2 and G to energize cooling blower speed.

If two-stage cooling is used, the Y1, Y2, G of the thermostat must be connected to Y1 of tap select interface board for low cooling, Y/Y2 of the furnace control board for high cooling and G of the furnace control board for continuous fan speed.

Optional Equipment

All wiring from furnace to optional equipment MUST conform to local codes or, in the absence of local codes with the latest edition of The National Electric Code, ANSI NFPA 70 and/or The Canadian Electric Code CSA C22.1. Install wiring in accordance with manufacturer’s instructions. The wiring MUST have a minimum temperature rating of 105° C.

Humidifier/Electronic Air Cleaner

The furnace is wired for humidifier and/or electronic air cleaner connection.

HUMIDIFIER - The HUM (24V) terminal is energized when the low pressure switch closes on a call for heat. The HUM (115V) is energized when the inducer is energized.

ELECTRONIC AIR CLEANER - EAC terminal is energized when there is a blower speed call, except it is NOT energized when blower operates in the hard-wired continuous fan mode.

!CAUTION

REDUCED FURNACE LIFE HAZARD

Failure to follow this caution may result in reduced furnace life.

Do NOT exceed 115V/1.0 amp. maximum current load for both the EAC terminal and the HUM terminal combined.

Furnace Control Board

The furnace control board has a fixed blower ON delay of 30 seconds for High Heat calls and 45 seconds for Low Heat calls. The blower OFF timing is factory preset at 140 seconds. If desired, the fan OFF delay can be reset to obtain the longest delay times while still maintaining comfort levels. See “Furnace Wiring Diagram”.

Dehumidification

The furnace control board has a dehumidification feature which reduces cooling airflow by 20% when the DEHUM terminal (1/4” male quick connect) is energized by 24VAC and there is a cooling call. DEHUM may be operated by a thermostat dehumidify (24VAC for dehumidify) command or a dehumidistat (switch closes on call for dehumidification) with one terminal connected to (Y1 for two-stage cooling or Y/Y2 for single-speed cooling applications) and the other terminal connected to DEHUM.

Furnace Control Fuse

The 24V circuit contains a 5-amp, automotive-type fuse located on furnace control board. (See Fig. 41) Any electrical shorts of 24V wiring during installation, service, or maintenance may cause fuse to blow. If fuse replacement is required, use only a fuse of identical size (5 amp.)

	115V. 60 Hz.
HOT	NEUT.	W
		W
		BK
		G
		Connection
		Box
Ground
			R
LowVoltage			C
TerminalBoard			C
TerminalBoard			W2
			W2
			W1
			Y/Y2
			G
W
R	G	SingleStage
		Thermostat
LowVoltage			R
LowVoltage			C
TerminalBoard			C
TerminalBoard
			W2
			W1
			Y/Y2
			G
W2		TwoStage
R W1		TwoStage
R W1		Thermostat
G

NOTE:115VAC/60Hz/single----phase

Operatingvoltagerange*:127VACmax,104VACmin.

* Permissible limits of voltage at which unit will operate satisfactorily

A07779

Fig. 40 - Electrical Connections

Tap Select Interface Board

The Tap Select Interface Board is used with the Variable Speed motor. There are DIP switches (SW2) for continuous blower adjust, heating blower adjust, cooling blower adjust and cooling on/off delay profiles. There is a jumper (J1) for slight blower adjustment, increase (+)/no change (NOM)/decrease (-). There is a jumper (J2) for airflow selection of Heat Pump EFFICIENCY or COMFORT. (EFFICIENCY provides no airflow reduction in airflow whether O is energized or not. COMFORT provides a 10% reduction in airflow when O is not energized with a cooling call).

The O terminal is available for use for Heat Pump applications, if desired.

The Y1 terminal (if a two-stage Air Conditioner or two-stage Heat Pump is used) will provide low cooling blower speed when energized. (Only Y/Y2 on the furnace control board is used if a single-stage Air Conditioner or Heat Pump is installed)