AAON H3 Series, Установка, эксплуатация и обслуживание

Страница: 40 / 80

40
connector (ASC) to false load the evaporator
when reduced suction pressure is sensed.
Field piping between the condensing unit
and the evaporator is required. Line sizes
must be selected to meet actual installation
conditions, not simply based on the
connection sizes.
Purge Circuit
The purge circuit is required on hot gas reheat
or hot gas bypass lines. The purge circuit
needs to be field furnished and installed at the
lowest point of the line set.
With this installation, oil drains into the drain
leg of the hot gas reheat line. Oil accumulates
until it reaches the level of the 3.2 mm (1/8”)
OD capillary tubing.
The combination of capillary action and the
pressure difference between the hot gas
reheat line (high pressure) and the suction
line (low pressure) causes the oil to travel
through the capillary tube into the suction
line of the first circuit to return the oil to the
compressor. The capillary tube connection to
the suction line of the first circuit must be a
minimum of 1.5 meters (5 feet) from the inlet
to the compressor to allow the oil time to
dissipate into the suction vapor and not slug
the compressor with liquid oil.
Adjusting Refrigerant Charge
Adjusting the charge of a system in the field
must be based on determination of liquid sub-
cooling and evaporator superheat. On a
system with a TXV, liquid sub-cooling is
more representative of the charge than
evaporator superheat but both measurements
must be taken.
Before Charging
Refer to the Unit Nameplate to determine
which refrigerant must be used to charge the
system.
Unit being charged must be at or near full
load conditions before adjusting the charge.
Units equipped with hot gas bypass must
have the hot gas bypass valve closed to get
the proper charge.
Units equipped with hot gas reheat must be
charged with the hot gas reheat valves closed
while the unit is in cooling mode to get the
proper charge. After charging, operate the
unit in reheat (dehumidification) mode to
check for correct operation.
Units equipped with heat pump options must
be charged in cooling mode to get the proper
charge. After charging, operate the unit in
heating mode to check for correct charge.
Charge may need to be adjusted for heating
mode. If adjustments are made in the heating
mode, cooling mode must be rerun to verify
proper operation.
Figure 24 - Hot Gas Purge Circuit
The Clean Air Act of 1990 bans the
intentional venting of refrigerant
(CFC’s and HCFC’s) as of July 1,
1992. Approved methods of recovery,
recycling or reclaiming must be
followed. Fines and/or incarceration
may be levied for non-compliance.
CAUTION