47
Evaporator Coils
The air handling unit coils are pressurized.
The copper caps must be punctured to
permit a gradual escape of the pressure prior
to un-sweating those caps. Immediately
couple the tubing to the indoor unit to avoid
exposing the coils to moisture. A properly
sized filter drier is furnished in the
condenser.
When
making
solder
connections, make sure dry nitrogen flows
through the lines, when heating the copper,
to prevent oxidization inside of the copper.
Field piping between the condensing unit
and the air handler is required.
Thermal expansion valve bulbs should be
mounted with good thermal contact on a
horizontal section of the suction line close to
the evaporator, but outside the cabinet, and
well insulated. On suction lines less than or
equal to 7/8” OD, mount in the 12 o’clock
position. On suction lines greater than 7/8”
OD, mount in either the 4 o’clock or 8
o’clock position.
Figure 20 - TXV Bulb Position
Hot Gas Reheat
Hot Gas Reheat (HGRH) is available for use
with DX systems that need humidity control.
The AAON modulating hot gas reheat
system diverts hot discharge gas from the
condenser to the air handling unit through
the hot gas line.
Field piping between the
condensing unit and the air handler is
required.
Connect the hot gas line from the
outdoor
unit
to
the
upper
stub-out
connection of the reheat coil in the air
handling unit.
The line delivers the hot discharge gas to the
reheat coil and/or the hot gas bypass valve,
so it is sized as a discharge line.
Hot Gas Bypass
Hot Gas Bypass (HGB) is available for use
with DX systems that may experience low
suction pressure during the operating cycle.
This may be due to varying load conditions
associated with VAV applications or units
supplying a large percentage of outside air.
Hot Gas Bypass is not necessary in units
with variable capacity compressors. The
system is designed to divert refrigerant from
the compressor discharge to the low pressure
side of the system in order to keep the
evaporator from freezing and to maintain
adequate refrigerant velocity for oil return at
minimum load.
Hot discharge gas is redirected to the
evaporator inlet via an auxiliary side
connector (ASC) to false load the evaporator
when reduced suction pressure is sensed.
Field piping between the condensing unit
and the evaporator is required.
Refrigerant-to-Water Heat Exchanger
Condenser water pump, condenser water
piping, cooling tower, pressure gauges,
strainers and all components of the
waterside piping must be field installed.
WATER-SOURCE HEAT PUMP
APPLICATIONS
Water-source heat pump units using
100% outside air must have electric
preheat if the application has a
potential for heat pump heating
operation with air entering the indoor
coil below 43°F with an entering
water loop temperature of 70°F.
CAUTION
Summary of Contents for M2 Series
Page 2: ......
Page 5: ...5 Split System Piping Diagrams 98 M2 Series Startup Form 115 Maintenance Log 121 ...
Page 35: ...35 Table 1 Electric and Gas Heating Capacities ...
Page 38: ...38 Figure 5 M2 Series Unit Four Point Lifting ...
Page 39: ...39 Figure 6 M2 Series Unit Eight Point Lifting ...
Page 58: ...58 Figure 32 Supply Fan Banding ...
Page 95: ...95 Figure 52 Filter Layout Viewed from the Upstream Side of the Cooling Coil ...
Page 98: ...98 Split System Piping Diagrams Figure 53 A C Split System Piping Suction Down ...
Page 99: ...99 Figure 54 A C Split System Piping Suction Up ...
Page 100: ...100 Figure 55 A C with LAC Split System Piping Suction Up ...
Page 101: ...101 Figure 56 A C with Modulating Hot Gas Reheat Split System Piping Suction Down ...
Page 102: ...102 Figure 57 A C with Modulating Hot Gas Reheat Split System Piping Suction Up ...
Page 103: ...103 Figure 58 A C with Hot Gas Bypass Split System Piping Suction Down ...
Page 104: ...104 Figure 59 A C with Hot Gas Bypass Split System Piping Suction Up ...
Page 107: ...107 Figure 62 Heat Pump Split System Piping Suction Down ...
Page 108: ...108 Figure 63 Heat Pump Split System Piping Suction Up ...
Page 109: ...109 Figure 64 Heat Pump with Modulating Hot Gas Reheat Split System Piping Suction Down ...
Page 110: ...110 Figure 65 Heat Pump with Modulating Hot Gas Reheat Split System Piping Suction Up ...
Page 111: ...111 Figure 66 Heat Pump with Hot Gas Bypass Split System Piping Suction Down ...
Page 112: ...112 Figure 67 Heat Pump with Hot Gas Bypass Split System Piping Suction Up ...