Bosch LM Split CS Series Installation, Operation And Maintenance Manual page 22

22 | Sequence of Operation
Some accessories have a built-in delay, and
hence, compressor operation is not
immediate. See "Field-Installed
Accessories" section on page #23 for more
detail.
When the thermostat calls for second-stage
cooling (Y2) the second stage (or full-compressor
capacity) is initiated. The fan ramps up to full
cooling airflow.
Once the thermostat is satisfied, the compressor
shuts down and the fan ramps down to either
fan-only mode or off over a span of 30 seconds.
A fault condition initiating a lockout will
de-energize the compressor irrespective of
which stage is engaged.
Heating Mode
The first two stages of heating (Y1 & Y2) operate in
the same manner as cooling, but with the reversing
valve de-energized. On a call for auxiliary heat
(W1), the fan ramps up to auxiliary heat airflow
immediately and the electric heater package is
energized along with the compressor. As the
thermostat is satisfied, the heaters will shut off as
soon as W1 is de-energized, and the compressors
will remain on until the thermostat stages are
satisfied.
If the unit compressor locks out for any
reason at this time, the electric heaters will
continue to function normally.
Once the thermostat is satisfied, the compressor
shuts down and the fan ramps down to either
fan-only mode or off over a span of 30 seconds. If
thermostat has two different output points, one
for Auxiliary heat and a different one for
Emergency heat, the two outputs must be
terminated on W1 units equipped with one stage
of Electric heat.
When using a 2-cool, 3-heat thermostat
both the W1 & W2 on the Heat Pump and
W2 & EM on the thermostat must be
connected together via a jumper.
8733827906 (2021/11)
Subject to change without prior notice
LM Split CS Series Heat Pump
LM Split CS Series Heat Pump