Economizer; Led Annunciator; Flow Proving Switch; Ddc Controls - Bosch LV Series Installation And Maintenance Manual

LV Heat Pump Series

Economizer

LV series heat pumps can be provided an optional
water side economizer. The water side
economizer option allows a cooling demand to be
satisfied by circulating cold water through a water-
to-air heat exchanger (economizer coil) mounted
to the return air opening of the heat pump instead
of energizing the compressor. The major
components of the economizer option are the
water-to-air heat exchanger, the three way water
diverting valve, the aquastat and the unit control
circuit.
The economizer option operates in the following
sequence:
• When the unit thermostat calls for cooling
operation AND the economizer aquastat
indicates that the supply water temperature is
below the aquastat set point, then heat pump
switches from compressor cooling to
economizer cooling mode.
• In economizer cooling mode the three way
diverting valve shifts, diverting water through
the economizer coil and then to the condenser
coil. The unit fan operates but the compressor
does not start. This mode effectively cools the
air passing through the heat pump with the
cold water supply instead of compressor
cooling.
• If the call for cooling is satisfied, then the heat
pump fan simply shuts off.
• If, during a call for cooling, the supply water
temperature climbs above the aquastat set
point, then the three way valve will divert water
back to the condenser coil and the heat pump
compressor will start in the cooling mode.
Note that the economizer coil incorporates its
own drain pan to collect condensate from the
coil. This pan MUST be independently trapped
and piped into the drain line for the heat pump.
The LV series economizer option is designed for
free return applications. If the heat pump is to
be connected to return air duct work, the
economizer may need to be slightly modified.
LV Heat Pump Series
The LV series economizer is designed for
cooling only. If heating economizer operation
is desired, consult the factory for applications
and design information.
Refer to the unit wiring diagram for control circuit
details.

LED Annunciator

LV series heat pumps can be equipped with an
optional LED annunciator kit. This LED kit can
provide a quick visual indication of whether or not
a heat pump is energized and if it has locked out on
a fault. The LED kit is mounted to the electrical
corner post of the heat pump and employs high
intensity LED's for better visibility. The LED kit will
exactly mirror the LED blink codes on the UPM
board (refer to the blink code table in the UPM
sequence of operation).

Flow Proving Switch

LV series heat pumps can be equipped with an
optional flow proving switch. This device senses a
pressure drop across the water side of the
condenser coil indicating water flow. When the
pressure drop rises to a pre-set value, the flow
proving switch will enable the compressor. If the
pressure drop across the condenser does not
reach the required value, then the unit compressor
is disabled.

DDC Controls

Factory mounted DDC controls are available as an
option on LV series heat pumps. Please refer to
the DDC control manuals and literature for details
on this option.
Options | 19
8 733 905 683 (2013/04)