Manual 2100-737A
Page
13 of 25
OPTIONAL OUTDOOR THERMOSTAT
APPLICATIONS
Since most equipment at the time of manufacture
is not designated for any specific destination of the
country and are installed in areas not approaching the
lower outdoor temperature range, outdoor thermostats
are not factory installed as standard equipment, but
are offered as an option. There are also different
applications for applying outdoor thermostats. The set
point of either type of outdoor thermostat application
is variable with geographic region and sizing of
the heating equipment to the individual structure.
Utilization of the heating Application Data, and the
heat loss calculation of the building are useful in
determining the correct set points.
NOTE:
The additional LAB (low ambient bypass) relay
is required to prevent heater operation during low
temperature cooling operation.
OPTIONAL COMPRESSOR CUTOFF
THERMOSTAT (See Figures 8 & 9)
Heat pump compressor operation at outdoor
temperatures below 0°F are neither desirable nor
advantageous in term of efficiency. An outdoor
thermostat can be applied to take the mechanical
heating (compressor) off line, and send the
(compressor) signal to energize electric heat in its
place (to make electric heat first stage heating). This
can also be applied to bank the quantity of available
electric heat. For example: A heat pump operates
with 10KW second stage heat – once the outdoor
thermostat has switched then operates 15KW without
the compressor as first stage heat.
FIGURE 8
Compressor Cutoff Thermostat Wiring
4 – 10KW 1 PH/6 & 9KW 3 PH
FIGURE 9
Compressor Cutoff Thermostat Wiring
15 – 20KW 1 PH & 3 PH
MIS-409A