6
Accessory description and usage (Listed alphabetically) continued
6.
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.
7.
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.
8.
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 Ap-
plication Guideline.
9.
Low-Ambient Pressure Switch
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 (approximately 200 psig to 365 psig). The control will maintain working head pressure at low-ambient temperatures down to 0°F
(–17.8°C) when properly installed.
Usage Guideline:
A Low-Ambient Pressure Switch or MotorMaster ®—Low-Ambient Controller must be used when cooling operation is used at outdoor tem-
peratures below 55°F (12.8°C).
10.
MotorMaster®—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 tem-
perature 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 ± –12°C).
Usage Guideline:
A MotorMaster ®—Low-Ambient Controller or Low-Ambient Pressure Switch must be used when cooling operation is used at outdoor tem-
peratures below 55°F (12.8°C).
Suggested for all commercial applications
11.
Outdoor Air Temperature Sensor
Designed for use with Carrier Thermostats listed in this publication. This device enables the thermostat to display the outdoor temperature. This device also is
required to enable special thermostat features such as auxiliary heat lock out.
Usage Guideline:
Suggested for all Carrier thermostats listed in this publication.
12.
Outdoor Thermostat
An SPDT temperature-actuated switch which turns on supplemental electric heaters when outdoor air temperature drops below a user-selected set point.
Usage Guideline:
Electric supplemental heat applications in non-variable speed indoor units when electric heat staging is desired.
13.
Pressure Guard Kit
A pressure switch kit that cycles the outdoor fan to limit the heating head pressure below a pre-determined pressure setting.
Usage Guideline:
Some local codes may require limiting the heating head pressure in the vapor line in some applications.
14.
Secondary Outdoor Thermostat
An SPDT temperature-actuated switch which turns on third-stage of supplemental electric heaters when outdoor air temperature drops below the second-stage
set point.
Usage Guideline:
Outdoor thermostat applications where electric heater is capable of 3-stage operation.
15.
Snow Stand
Coated wire rack which supports unit 18 in. above mounting pad to allow for drainage from unit base.
Usage Guideline:
Suggested in the following applications:
Heat pump installations in heavy snowfall areas.
Heat pump installations in snowdrift locations.
Heat pump installations in areas of prolonged subfreezing temperatures.
All commercial installations.
16.
Sound Hood
Wraparound sound reducing cover for the compressor. Reduces the sound level by about 2 dBA.
Usage Guideline:
Suggested when unit is installed closer than 15 ft to quiet areas—bedrooms, etc.
Suggested when unit is installed between two houses less than 10 ft apart.
17.
Support Feet
Four stick-on plastic feet which raise the unit 4 in. above the mounting pad. This allows sand, dirt, and other debris to be flushed from the unit base; minimizes
corrosion.
Usage Guideline:
Coastal installations.
Windy areas or where debris is normally circulating.
Rooftop installations.
18.
Thermostatic Expansion Valve (TXV) Bi-Flow
A modulating flow-control valve which meters refrigerant liquid flow rate into the evaporator in response to the superheat of the refrigerant gas leaving the
evaporator.
Usage Guideline:
Required in all heat pump applications designed with Puron refrigerant.
19.
Time-Delay Relay
An SPST delay relay which briefly continues operation of indoor blower motor to provide additional cooling after the compressor cycles off.
Note:
Most indoor unit controls include this feature. For those that do not, use the guideline below.
Usage Guideline:
For improved efficiency ratings for certain combinations of indoor and outdoor units. Refer to ARI Unitary Directory
.
