Factory-Installed Options
14 Factory-Installed Options
A number of options are available on EC Series of Heat Pumps.
The following details the purpose, function, and components of
each option.
14.1 Flow Proving Switch (DPS)
The function of the Flow Proving Switch is to prevent or stop
compressor operation if the water supply fails. This prevents the
unit from locking out on a safety requiring a manual reset to
restart. The switch is installed in line between the water entering
and leaving connections. If the pressure drop falls below the set
value, the switch opens and de-energizes the DPS relay, thereby
stopping the compressor. The blower operation is not be
affected by this option.
14.2 Boilerless Control
The Boilerless Control option allows the water source heat pump
to be operated in heating mode safely when installed in a system
that has no means of heating the water loop. This option consists
of an adjustable aquastat and relay. During the thermostat call for
heating, if the aquastat detects a drop in water temperature
below a preset limit, the relay disengages the compressor
contactor and provides a dry-contact closure to divert unit
operation from compressor heating to an alternate heat source
(generally field-provided electric heat).
14.3 Variable Frequency Drive (VFD)
The VFD option for fan motors is available as a means to adjusting
the airflow to any CFM value for ideal space conditioning.
14.4 Phase Monitor
This option offers protection against phase loss/reversal and
imbalance. Upon application of power with the safety switches
closed, the load energizes. If any of the safety switches open for
longer than 600 ms, the fault light comes ON and the load will
stay de-energized regardless of the state of the safety switches.
Power must then be removed for 100 ms and safety switches
must be closed in order to re-energize the load, upon which the
fault light turns OFF.
14.5 Hot Gas Reheat (HGRH)
HGRH is an active dehumidification option available on the EC
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 HGRH can efficiently
remove humidity from the return air without altering the sensible
temperature of the space.
There are several ways to control the heat pumps with hot gas
reheat. Y
ou should choose the means that best suits your specific
application. The Typical Wiring Diagram illustrates one possible
control sequence. Most heat pump compatible thermostats in
conjunction with a humidistat are acceptable for use.
Heat pumps with HGRH need to be connected to a humidistat
along with a traditional thermostat or a combination
thermostat/humidistat.
The thermostat connection “O” output for reversing valve
energized in cooling mode is required.
14.5.1 Hot Gas Reheat Sequence of Operation—ON/OFF
Control
The sequence of operation in the cooling and heating modes is
the same a
s a regular heat pump. In reheat mode, the Reheat
Relay Coil is energized through the “H” circuit when a call is sent
from the humidistat. The Cooling Relay remains de-energized
enabling the Reheat Solenoid. The Blower Relay, Reversing
Valve, and Compressor Contactor are all energized through
contacts on the Reheat Relay.
NOTICE
Reheat always operates in cooling mode.
Should the temperature in the space increase above the set
point, the compressor terminal Y is energized, which
de-energizes the Reheat Valve putting the unit into straight
cooling
mode. A call for cooling or heating will always take
precedence over Hot Gas Reheat.
14.6 Modulating Hot Gas Reheat (MHGRH)
The purpose of MHGRH is to deliver air at or close to neutral
conditions. A typical application for this would be in treating
100% outside air. This air would be ducted directly into the space
relieving the unit handling the zone of any outside air load. This
can result in a smaller zone unit, less air flow, and a savings in
both the initial and operating costs. Control of the hot gas
modulation is by the wall-mounted thermostat or the unit
mounted DDC. A separate controller is used to control the unit
itself.
32 |
EC Series Heat Pumps — 8733841499 (2024/05)
To Next Page
Loading...
