System
Load Compliance – Continuous Dehumidification and Temperature Control
The
APR Control converts a direct expansion system into a modulating direct
expansion system. This means that system capacity will vary to match
changing load conditions. System load compliance is achieved. In addition
to capacity modulation, the APR Control maintains the evaporator coil
in a dehumidifying mode, while modulating system capacity. As a result,
the APR Control enhanced system maintains constant temperature with
excellent latent heat removal and lower overall humidity levels.At the
same time, the APR Control maintains the system in a continuous dehumidifying
mode. The air conditioning or heat pump system with the APR Control
drives the system into a constant temperature mode and stabilizes the
humidity level to the ability of the evaporator coil to remove latent
heat. Coil row depth and fins per inch construction determine the bypass
factor, which controls the effectiveness of the dehumidifying mode during
partial load conditions. The APR Control is controlled by the enthalpy
(sensible heat plus latent heat) or the total heat of the air. This
is the reason the APR Control is so effective in the control of the
system’s dehumidification process.
Energy
Savings and Extended Equipment Life
The APR Control
saves energy in three ways.
- First, the APR
Control reduces the KW input power to the compressor, corresponding
to the reduced load.
- Second, the
APR Control saves energy by the reduction of excessive compressor
cycling.
- Third, in systems
where re-heat is used to maintain the dehumidification effect, additional
energy is saved because the APR Control significantly reduces the
required reheat to maintain the system in a dehumidifying mode.
Because the APR
Control reduces compressor cycling, there is considerable less wear
and tear on the compressor over the life span of the system leading
to extended life expectancy and reduced cost of repairs over the life
of the equipment.
Multi-Evaporator
Zoning
By controlling
individual fan coil evaporators with simple thermostatically controlled
solenoid valves, the APR Control makes multi-evaporator zoning possible.
The APR Control
modulates the capacity of the condensing unit to match the demand of
the multi-evaporator zone fan coils. A single loop refrigerant circuit
with branch connections to each evaporator is all that is required.
Local thermostats wired to liquid line solenoid valves at each branch
will provide local control for each zone while the APR Control manages
refrigerant flow.
Multi-evaporator
zoning with the APR Control can significantly reduce equipment and ductwork
needs. The APR Control has been used for 2 zone systems serving a residence
all the way to a 10 zone system serving flexible retail space.
In addition, multi-evaporator
zoning reduces the possibility of cross contamination via interzone
air circulation. The APR Control make area isolation possible in hospitals,
nursing homes, hotels and schools – all from direct expansion air
conditioning system.
In applications
where there are standard roof top units being applied for space cooling,
the APR Control can help eliminate the need for independent fresh air
conditioning. With the addition of a separate coil in a rooftop unit’s
outside air intake, the multi-evaporator zoning application of the APR
Control allows the fresh air coil to precondition the air entering the
RTU. This preconditioning coil will remove humidity and reduce air temperature
of the outside air even when the thermostat in the space is not calling.
Eliminating humidity related problems, such as mold and mildew, when
ventilation standards for occupancy are high is now a simple solution
with the APR Control.
Elimination
of Excessive Compressor Cycling and Coil Freezing
Compressor cycling
is often the result of too much system capacity for changing load conditions.
Excessive compressor cycling is one of the primary causes of system
failure and a major source of repair costs. These costs can be minimized
by the addition of the APR Control to the refrigeration circuit. The
APR Control will rapidly and automatically modulate system capacity
to match load conditions and eliminate excessive compressor cycling.
Reduced air flow
from restricted ductwork or insufficient duct space can result in coil
icing or freezing. Prolonged freezing can cause system breakdowns or
compressor damage. The ability of the APR Control to modulate a systems
capacity will eliminate this problem because the APR Control is set
to never allow the coil temperature to fall below freezing.
