AAON M2-036 - Manual (Page 56)

56
An aquastat is included with the field
installed water piping kit and is used to
modulate water flow through the
economizer coil. The controller is mounted
in the controls compartment. Electrical
connections must be field wired. The
temperature bulb requires field mounting.
Care should be taken to firmly mount the
bulb on the supply water piping, but not to
dent the bulb when installing. The aquastat
has a temperature calibration range
adjustment of -10°F to 100°F and must be
field set.
Mineral content of the condenser water must
be controlled. All make-up 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.
Field provided and installed water treatment
program must be compatible with stainless
steel, copper, aluminum, ABS plastic, and
PVC. Batch feed processes should never be
used as concentrated chemicals can cause
corrosion. Never use hydrochloric acid
(muriatic acid) or chlorine as it will corrode
stainless steel.
Hot Water and Steam Coils
Factory installed one or two row hot water
heating coils can be factory mounted. These
coils are supplied from a hot water source
through separate piping from the condenser
water source. All controls for heating
operation are field supplied and field
installed.
Always connect the supply to the top of the
coil and the return to the bottom. Water coils
should not be subjected to entering air
temperatures below 38°F to prevent coil
freeze-up. If air temperature across the coil is going to be below this value, use a glycol
solution to match the coldest air expected.
Water supply lines must be insulated,
properly fastened, drained, and supported
according to local code requirements.
Air handling units with steam heating coils
MUST BE installed high enough to allow
for a minimum of 1 foot condensate drop leg
off of the steam coil, or as recommended by
the steam trap manufacturer. Lines should
be insulated with approved insulation and be
properly fastened, sloped, and supported
according to local code requirements.
Chilled Water Coils
Factory installed four or six row chilled
water cooling coils can be factory mounted.
These coils are supplied from a chilled water
source through separate piping from the
condenser water source. All controls for the
cooling coil are field supplied and field
installed.
Water supply lines must be insulated with
closed cell type pipe insulation or insulation
that includes a vapor barrier. Lines should
be properly fastened, drained and supported
according to local code requirements, and
job specifications.
Electric Heating
Heating is accomplished by passing
electrical current through a specified amount
of resistance heaters which will produce the
Piping shall be in accordance with
national and local codes. Pressure
limiting devices, backflow preventers
and all other safety requirements are
the sole responsibility of the installing
contractor.
WARNING