Carrier Base 25HBR Installation And Start-Up Instructions Manual page 6

(See Thermostat Installation Instructions for wiring specific unit combinations.)
Use No. 18 AWG color coded, insulated (35°C minimum) wire. If
thermostat is located more than 100 ft from unit, as measured
along the control voltage wires, use No. 16 AWG color coded wire
to avoid excessive voltage drop.
All wiring must be NEC Class 1 and must be separated from
incoming power leads.
Use furnace transformer, fan coil transformer, or accessory trans-
former for control power, 24v/40va minimum.
NOTE: Use of available 24v accessories may exceed the mini-
mum 40va power requirement. Determine total transformer load-
ing and increase the transformer capacity or split the load with an
accessory transformer as required.
IMPORTANT: Check factory wiring and wire connections to
ensure terminations are secured properly. Check wire routing to
ensure wires are not in contact with tubing, sheet metal, and so
forth.
Step 9—Compressor Crankcase Heater
When equipped with a crankcase heater, furnish power to heater a
minimum of 24 hr before starting unit. To furnish power to heater
only, set thermostat to OFF and close electrical disconnect to
outdoor unit. A crankcase heater is required if refrigerant tubing is
longer than 80 ft.
TYPICAL
HP THERMOSTAT FAN COIL
24 VAC HOT R
C
24 VAC COM
HEAT STAGE 2 W2
COOL/HEAT
Y
STAGE 1
G
INDOOR FAN
RVS COOLING O
EMERGENCY
E
*
IF AVAILABLE
HEAT
LEGEND
24-V FACTORY WIRING
24-V FIELD WIRING
FIELD SPLICE CONNECTION
ODT
OUTDOOR THERMOSTAT
EMERGENCY HEAT RELAY
EHR
SUPPLEMENTAL HEAT RELAY
SHR
Fig. 9—Generic Wiring Diagram
6
HEAT
PUMP
R
R
C
C
*
W2
W2
*
E
Y
*
W3
G
O
Step 10—Install Electrical Accessories
Refer to the individual instructions packaged with kits or acces-
sories when installing.
Step 11—Start-Up
UNIT OPERATION AND SAFETY HAZARD
Failure to follow this caution may result in minor personal
injury, equipment damage, or improper operation.
To prevent compressor damage or personal injury, observe
the following:
•Do not overcharge system with refrigerant.
•Do not operate unit in a vacuum or at negative pressure.
•Do not disable low pressure switch.
In scroll compressor applications:
•Dome temperatures may be hot.
A02325