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LV Heat Pump Series
At water temperatures of 85° F, the reheat coil can
recover 95% to 100% of the sensible capacity of the
evaporator. At water temperatures below 60°F, the
reheat coil can only recover 5% to 25% of the sensible
capacity of the evaporator.
Refer to the unit wiring diagram for control circuit
details.
Hot Gas Bypass
(Available on size 024 and larger)
The hot gas bypass option can be used to reduce cooling
capacity in low air temperature applications such as
applications with a large percentage of outside air.
As the air temperature entering the unit drops, the
suction pressure and evaporating temperature start to
drop as well.
At an evaporating temperature of 40°F the hot gas
bypass valve will start to divert a portion of the hot
compressor discharge gas to the low temperature liquid
entering the evaporator coil. This hot gas serves to warm
the evaporator coil and reduces the cooling capacity of
the heat pump.
Note that the hot gas bypass valve is inoperative in
the heating mode.
Internal 2-Way Water Valve
In many applications, including variable pumping and
well water installations, a motorized water valve is
required on the heat pump water circuit. On the LV
series this water valve can be factory mounted and wired
internally to the unit.
The LV series internal water valve option features a
24VAC motorized water valve rated to 450 psig working
pressure. This valve is wired to open on a thermostat call
for compressor operation (heating or cooling) and will
remain open as long as the thermostat calls. The valve
can remain seated with up to 20 psi of back pressure on
all sizes.
The valve consists of two main parts: the valve body and
the actuator. The valve body is brazed into the leaving
water line of the heat pump and is a permanent part of
the unit. The valve actuator can be easily removed from
the valve body for service.
Refer to the water side pressure drop table in the
troubleshooting section of this manual to determine the
appropriate pressure drop across the heat pump with
and without the water valve option.
Note that the 2-Way Water Valve option will add
additional pressure drop between the water in and
water out connections of the heat pump.
Note that this water valve cannot be used as an
isolation valve.
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.
The LV series economizer is designed for cooling
only. If heating economizer operation is desired,
consult the factory for applications and design
information.
Note: See Page #9 Figure #7 for Condensate Drain
Options | 25
8 733 905 683 (2016/09)
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