Carrier 25HCD3, Product Data

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ACCESSORY USAGE GUIDELINE
Accessory
REQUIRED FOR LOW---AMBIENT
COOLING APPLICATIONS
(Below 55

F / 12.8

C)
REQUIRED FOR
LONG LINE APPLICATIONS*
REQUIRED FOR
SEA COAST APPLICATIONS
(Within 2 miles / 3.22 km)
Accumulator Standard Standard Standard
Ball Bearing Fan Motor Yes
{
No No
Compressor Start Assist Capacitor and
Relay
Yes Yes No
Crankcase Heater
Yes
Yes
No
Evaporator Freeze Thermostat Yes No No
Hard Shutoff TXV Yes Yes Yes
Isolation Relay Yes No No
Liquid Line Solenoid Valve No See Long---Line Application Guideline No
Motor Master

Control or
Low Ambient Switch
Yes No No
Support Feet Recommended No Recommended
* For tubing line sets between 80 and 200 ft. (24.38 and 60.96 m) and/or 20 ft. (6.09 m) vertical differential, refer to Residential Split---System Longline
Application Guideline.
{
Additional requirement for Low---Ambient Controller (full modulation feature) MotorMaster
r
Control.
Accessory Description and Usage (Listed Alphabetically)
1. Ball--Bearing Fan Motor
A fan motor with ball bearings which permits speed reduction
while maintaining bearing lubrication.
Usage Guideline:
Required on all units when using MotorMaster
r
2. Compressor Start Assist -- Capacitor and Relay
Start capacitor and relay gives a ”hard” boost to compressor motor
at each start up.
Usage Guideline:
Required for reciprocating compressors in the following
applications:
Long line
Low ambient cooling
Hard shut off expansion valve on indoor coil
Liquid line solenoid on indoor coil
Required for single--phase scroll compressors in the
following applications:
Long line
Low ambient cooling
Suggested for all compressors in areas with a history of
low voltage problems.
3. Compressor Start Assist — PTC Type
Solid state electrical device which gives a ”soft” boost to the
compressor at each start--up.
Usage Guideline:
Suggested in installations with marginal power supply.
4. Crankcase Heater
An electric resistance heater which mounts to the base of the
compressor to keep the lubricant warm during off cycles. Improves
compressor lubrication on restart and minimizes the chance of
liquid slugging.
Usage Guideline:
Required in low ambient cooling applications.
Required in long line applications.
Suggested in all commercial applications.
5. Evaporator Freeze Thermostat
An SPST temperature--actuated switch that stops unit operation
when evaporator reaches freeze--up conditions.
Usage Guideline:
Required when low ambient kit has been added.
6. Isolation Relay
An SPDT relay which switches the low--ambient controller out of
the outdoor fan motor circuit when the heat pump switches to
heating mode.
Usage Guideline:
Required in all heat pumps where low ambient kit has
been added.
7. Liquid--Line Solenoid Valve (LLS)
An electrically operated shutoff valve which stops and starts
refrigerant liquid flow in response to compressor operation. It is to
be installed at the outdoor unit to control refrigerant off cycle
migration in the heating mode.
Usage Guideline:
An LLS is required in all long line heat pump
applications to control refrigerant off cycle migration in
the heating mode. See Long Line Guideline.
8. Low--Ambient Pressure Switch Kit
A long life pressure switch which is mounted to outdoor unit
service valve. It is designed to cycle the outdoor fan motor in order
to maintain head pressure within normal operating limits. The
control will maintain working head pressure at low--ambient
temperatures down to 0
_
F (--18
_
C) when properly installed.
Usage Guideline:
A Low--Ambient Pressure Switch or MotorMaster
r
Low--Ambient Controller must be used when cooling
operation is used at outdoor temperatures below 55
_
F
(12.8
_
C).
9. MotorMaster
r
Low--Ambient Controller
A fan--speed control device activated by a temperature sensor,
designed to control condenser fan motor speed in response to the
saturated, condensing temperature during operation in cooling
mode only. For outdoor temperatures down to --20
_
F (--28.9
_
C), it
maintains condensing temperature at 100
_
F

10
_
F (37.8
_
C

6.5
_
C).
Usage Guideline:
A MotorMaster
r
Low Ambient Controller or
Low--Ambient Pressure Switch must be used when
cooling operation is used at outdoor temperatures
below 55
_
F (12.8
_
C).
Suggested for all commercial applications.
25H
C
D
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