AAON M2-036 - Manual (Page 44)

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Insulate the entire length of the HGB line
with a minimum 1 inch thick Armaflex
insulation.
Hot Gas Bypass Piping Considerations for
Evaporator below Condensing Unit
The line must slope downward from the
HGB valve toward the evaporator.
Hot Gas Bypass Line Guidelines
Choose a small size line to ensure oil return,
and minimize refrigerant charge.
Maintain velocities below a maximum of
4,000 fpm. A general minimum velocity
guideline to use is approximately 1,000 fpm.
Hot Gas Reheat
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.
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.
Discharge lines should be sized to ensure
adequate velocity of refrigerant to ensure oil
return, avoid excessive noise associated with
velocities that are too high, and to minimize
efficiency losses associated with friction.
Pitch the hot gas line in the direction of flow
for oil return.
When installing hot gas reheat risers, a drip
leg must be provided at the lowest point in
the system. The drip leg must be vertical, its
diameter should be the same as the diameter
of the riser, and it should be 1 foot long. Run
a drip line, using 1/8 inch capillary tube, 10
feet in length, from the drip leg to the
suction line. Connect the drip line a minimum of 1-inch above the bottom of the
drain leg.
Insulate the entire length of the hot gas line
with a minimum 1 inch thick Armaflex
insulation.
Hot Gas Reheat Guidelines
Maintain velocities below a maximum of
3,500 fpm. A general minimum velocity
guideline is 2,000 fpm.
Water-Cooled Condenser
Condenser water pump, condenser water
piping, cooling tower, pressure gauges,
strainers and all components of the
waterside piping must be field installed.
Open Loop Applications
This product contains one or more
refrigerant-to-water heat exchangers made
of 316 Stainless Steel. 316 Stainless Steel is
subject to severe corrosion and failure when
exposed to chlorides.
Do not allow water containing any form of
chlorides to enter this heat exchanger.
Common forms of chlorides include:
1. Sea water mist entering an open cooling
tower system.
2. Contaminated make-up water containing
salt water.
OPEN LOOP APPLICATIONS
Failure of the condenser as a result
of chemical corrosion is excluded
from coverage under AAON Inc.
warranties and the heat exchanger
manufacturer’s warranties.
WARNING