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water level will swing between the medium
and high water levels. The maximum high
water level must be 1” below the overflow
drain which occurs after the makeup water
valve shuts off when the water level reaches
the high level probe.
Figure 31 - Water Makeup Valve
Maintain makeup water supply pressure
between 15 and 60 psig for proper operation
of the valve. The makeup water valve
assembly must be inspected monthly and
adjusted as required. Replace the valve seat if
leakage occurs when the valve is in the closed
position.
Water Treatment System
All AAON evaporative condensers come
equipped with a water treatment system that
must be maintained by a local water
treatment professional trained in the water
treatment of evaporative condensers. This
system consists of a controller,
three
chemical pumps and storage tanks, a
conductivity sensor, a motorized ball valve
for water bleed, and a water meter.
One chemical pump and tank is typically
used for a de-scaling chemical to prevent
scale from forming in the condenser. The
other two pumps and tanks are typically used
for two different biocides (to kill any
microorganisms that could grow in the
condenser). Two biocides are used to prevent
organisms from becoming resistant to one
chemical.
The mineral content of the water must be
controlled. All makeup water has minerals in
it. As water is evaporated from the condenser,
these minerals remain. As the mineral content
of the water increases, the conductivity of the
water increases. The water treatment
controller monitors this conductivity. As the
water conductivity rises above set point, the
controller will open a motorized ball valve on
the discharge side of the condenser pump and
dumps water into the condenser drain until
conductivity is lowered. While the motorized
ball valve is opened, the controller will not
disperse chemicals.
The chemicals are dispersed by the water
treatment controller based on the scheduled
input by the water treatment professional.
The water meter measures the quantity of
makeup water used by the condenser.
Any 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 acid (muriatic acid) as it will
corrode stainless steel.
Evaporative Condenser Sequence of
Operation
On a call for cooling, the condenser pump is
activated. A pressure switch in the pump
discharge is bypassed for six seconds by a
time delay relay in order for the pump to
establish recirculating water flow. If flow is
not proven within the six seconds, the
pressure switch opens, breaking the safety
circuit, thereby shutting down the entire
Summary of Contents for RZ Series
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