Carrier 25HBC3 Series Product Data page 7

Accessory Description and Usage (Listed Alphabetically) - - CONTINUED
10. 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.
11. Outdoor Thermostat
An SPDT temperature- -actuated
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.
12. 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.
13. Snow Stand Rack
Coated wire rack which supports unit 18 in. (457.2 mm) 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 snow drift locations.
Heat pump installations in areas of prolonged
subfreezing temperatures.
All commercial installations.
switch which turns on
14. 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.
(4.577 m) to quiet areas, bedrooms, etc.
Suggested when unit is installed between two houses less
than 10 ft. (3.05 m) apart.
15. 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:
Accessory required to meet AHRI rating and system
reliability, where indoor not equipped.
Required in all heat pump applications designed with
Puron refrigerant.
16. 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:
Accessory required to meet AHRI rating, where indoor
not equipped.
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