Bosch LM Series, Installation, Operation And Maintenance Manual

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Options | 15 LM Series Heat Pump
8 733 905 315 (2013/9) Revised 09-13
OPTIONS
Number of factory installed options are available
on LM Series of Heat Pumps. The following details
the purpose, function and components of each
option.
Hot Gas Reheat (HGRH)
Hot gas reheat is an active dehumidification option
available on the LM series that cools and
dehumidifies return air, and then reheats it back to
approximately entering dry bulb temperature using
waste compressor heat. In this way, a unit with Hot
Gas Reheat can efficiently remove humidity from
the return air without altering the sensible
temperature of the space.
The reheat option consists of a refrigerant to air
heat exchanger (reheat coil) mounted down
stream of the evaporator coil. When there is a
signal for dehumidification AND the sensible space
temperature is satisfied, the unit will operate in
reheat mode. In reheat mode the heat pump will
operate at full load cooling and will divert
discharge gas from the compressor to the reheat
coil, effectively cooling and dehumidifying the air
and then reheating it back to a temperature close
to the entering dry bulb temperature. If there is a
call for sensible cooling while the unit is operating
in the reheat mode, then the unit will revert to
cooling until the sensible demand is satisfied.
Electric Heat
Internally mounted supplemental electric heat is
available on select models of the LM series.
Electric heating elements can operate along with
reverse cycle heating as auxiliary heat or in lieu of
reverse cycle heating (refrigeration heating) as
emergency backup heat.
Availability matrix, including available nominal kW
capacities is shown below:
Constant Airflow Motor
The Constant Airflow Motor is an Electronic
Commutated Motor (ECM) that provides a
constant air flow over a wide range of external
static pressures, while optimizing the power
consumption of the motor.
This option allows the unit to have different air
flow settings depending on the mode that the unit
is operating; i.e heating, cooling, fan only, hot gas
reheat, etc.
Fan Status Switch
The fan status switch is a Current Transformer
(CT) that monitors the current flow to the supply
fan motor. It’s default is Normally Open (NO)
circuit when the motor is not running, and closes
once it senses current flow.
Pump Status Switch
The pump status switch is a Current Transformer
(CT) that monitors the current flow from the
condenser pump motor. It’s default is Normally
Open (NO) when the motor is not running, and
closes once it senses current flow.
Heat pumps with hot Gas Reheat need to be
connected to a humidistat along with a
traditional thermostat or a combination
thermostat/humidistat.
Internal mounted Electric Heat is only available
on top blow vertical cabinets, end blow
horizontal cabinet .
Internal electric heat cannot be provided with
hot gas reheat. Units with internal electric heat
must have 2 field power supplies.
Heater
Model
KW Stgs Btu/h Product Series Compatibility
208V 230V 208V 230V LM024 LM036 LM048 LM060 LM070
Kw05- 3.6 4.8 1 12300 16300 x x x x x
Kw10- 7.2 9.6 2 24600 32700 x x x x
Kw15 10.8 14.4 2 36900 49100 x x x
Kw20 14.4 19.2 2 49200 63400 x x
x available
Please refer to the ECM Interface Board Section
(Pg. 14) for more information.