AAON RN Series Installation Operation & Maintenance page 79

Before connection to the unit the condenser
water system must be flushed to remove
foreign material that could cause condenser
fouling. A screen strainer with a minimum of
20 Mesh is provided ahead of the condenser
inlet to prevent condenser fouling and
internal tube damage.
Mineral content of the condenser water must
be controlled. All makeup water has minerals
in it and as the water is evaporated in the
cooling tower, these minerals remain. As the
mineral content of the water increases, the
conductivity of the water increases.
CAUTION
WATER PIPING
Follow national and local codes when
installing water piping. Connections to
the unit must incorporate vibration
eliminators to reduce noise and
vibration and shutoff
facilitate servicing. Supply and return
water piping must be at least as large
as the unit connections and larger
depending on length of runs, rise and
bends.
Field provided and installed water treatment
program must be compatible with stainless
steel, copper, aluminum, ABS plastic, and
PVC. Batch feed processes must never be
used as concentrated chemicals can cause
corrosion. Never use hydrochloric
(muriatic acid) or chlorine as it will corrode
stainless steel.
valves to
NOTE: Ball valves must be installed in the
condenser water supply and return lines for
unit isolation and water flow balancing. All
manual flow valves must be of the ball valve
design. Globe or gate valves must not be used
due to high pressure drops and poor throttling
characteristics.
Pressure
acid
recommended in condenser water supply and
return lines for system balancing. These
openings must be 5 to 10 pipe diameters from
the unit water connections. To allow for
mixing and temperature stabilization, wells
in the water piping must extend at least ½
pipe diameter into the pipe.
CAUTION
PVC (Polyvinyl Chloride) and CPVC
(Chlorinated Polyvinyl Chloride) are
vulnerable to attack
chemicals. Polyolester
used with R-410A
refrigerants, even in trace amounts, in
a PVC or CPVC piping system will
result in stress cracking of the piping
and fittings and complete piping
system failure.
CAUTION
Each heat exchanger
equipped with a refrigerant pressure
relief device to relieve
should excessive
pressures (>675 psig) occur. Codes
may require installing contractor to
connect and route
outdoors. The relief valve has a 5/8"
male flare outlet connection.
and temperature
by certain
(POE) oils
and other
may be
pressure
condensing
relief piping
ports are
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