Carrier 50HQ User Manual download pdf (Page 6)

2. Splice yellow and black power leads from control

box to yellow and red motor leads. (Yellow-to-

yellow and black-to-red.)

CONNECT CONTROL POWER WIRING (24-v)

— Power leads are brought thru 1 / 2-in. hole pro

vided in unit, Fig. 1 and 2. Extend leads to control

wiring terminal board located on top of control box,

Fig. 7. Connect leads to terminal board as shown

in Fig. 6.

Use Carrier-specified room thermostat and sub

base for proper unit operation. Be sure that field-

installed jumper wire is connected between subbase

terminals W and Y. Set thermostat heat anticipator

at 0.45 amp for 1-phase units and 0.50 amp for

3-phase units.

FAN SPEED

SELECTOR BL(

(MOLEX PLUG

COMPRESSOR

Fig. 7 — Typical Component Arrangement

(50HQ014-042 Shown)

_R_y e l -

-^YEL-

1-PHASE

CONN. TO

DISCON NECT-

PER NEC

GROUND

LEAD

—^b lk —

___

.GROUND

—[a] LUG

3-PHASE

CONN. TO

DISCONNECT-

PER NEC

— — —

—^YEL —

—^^YEL —

GROUND

LEAD

^GROUND

—C^LUG

50HQ.VQ

HEAT PUMP

CONTROL BOX

50HQ.V0

HEAT PUMP

CONTROL BOX

3-PHASE

Fig. 6 — Line Power Connections

START-UP

Water Flow and Temperature Data

1. Consider design water flow rates for efficient

operation. See Table 4 for permissible water flow

range.

2. Ensure that water temperature entering unit is

between 60 F minimum and 90 F maximum. If

water temperature below 60 F must'be used,

insulate supply line and install a secondary drain

pan under the unit to remove condensate from

heat exchanger and internal plumbing.

CAUTION: Water temperature outside

specified temperature range may cause

damage to unit. Do not jumper low tempera

ture switch in order to use ethylene ^ycol

3. Ensure that supply water is clean and air is

purged from system. Air in supply water causes

scaling in heat exchanger. Foreign material in

water and/or excessive velocity of water can

cause damage to tubing.

To Start Unit — Ensure that air filter is in place on

unit filter flanges provided. Do not operate unit

without filter in place. Adjust the thermostat as

follows:

1. Set selector switch at OFF.

2. Turn on main disconnect switch to unit.

3. Set fan switch as desired (ON or AUTO.).

4. Set thermostat dial at desired temperature.

5. Set selector switch at HEAT or COOL.

Check system refrigerant charge. See SERVICE,

Refrigerant Charging on page 8.

Unit Single-Phase Compressors that are

equipped with a compressor start thermistor (PTC

device) — When supply voltage is within limits

indicated on nameplate and compressor will not

start, check the thermistor with an ohmmeter.

If the PTC is good, and the compressor does not

start, disconnect the PTC from the starting circuit

and give unit a temporary capacitance boost. Refer

to Carrier Standard Service Techniques Manual,

Chapter 2, for details on capacitance boost pro

cedure. If unit does not start with capacitance boost,

compressor may be defective. If unit does not start,

check starting capability with PTC assistance. If

questionable, remove PTC, add start capaeitor and

start relay per start kit installation instructions.

W.A.RNING: Capacitance boost or installation

of start capacitor and start relay should be per

formed by trained personnel., improper pro

cedure could cause personal injury or equipment

damage.

Unit Controls and Safety Devices

HIGH-PRESSURE RELIEF VALVES (except

50HQ,VQ014) is located in compressor. Relief valve

opens at a pressure differential of approximately

550 psi between suction (low side) and discharge

(high side) to allow pressure equalization.

CURRENT AND TEMPERATURE SENSITIVE

OVERLOAD (linebreak) internal on all compres

sors except on 50HQ,VQ014 which has external

shell mounted overload. Overload resets auto

matically when internal compressor motor tempera

ture drops to a safe level (overloads may require up

to 45 minutes to reset). When an internal overload is

suspeeted of being open, check by using an ohm-

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Carrier 50HQ User Manual Page 6

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