AAON RQ-006 - Manual (Page 47)

47
Glycol solution should be used if ambient
temperatures are expected to fall below
freezing or if the loop entering water
temperature to the unit is below 50°F while
operating in the heating mode (heat pump
units only).
Adding glycol to condenser water
causes an increase in pressure drop and also
results in a decrease in unit performance.
A
minimum concentration of 20% glycol
solution is recommended.
Table 9 - Glycol Freezing Points
% Glycol Ethylene
Glycol
Propylene
Glycol
20 18°F 19°F
30 7°F 9°F
40 -7°F -6°F
50 -28°F -27°F
Water loop piping that runs through
unheated areas or outside the building
should be insulated.
Water Piping
Installing
contractor must ensure a
differential pressure switch or water flow
switch is installed between the condenser
water supply and return connections. This
sensor provides a signal to the unit
controller that water flow is present in the
refrigerant-to-water heat exchanger and the
unit can operate without damaging unit
components.
Table 10 - Condenser Water Connections
Model (RQ-)
Supply and Return
Connection Size
002 3/4” Sweat
003, 004, 005, 006
1” Sweat
Only use approved water pipe material.
Avoid using galvanized material for water
lines/fittings as the material is corrosive and
may cause fouling of the water system.
WATER PRESSURE
Prior to connection of condensing
water supply, verify water pressure is
less than maximum pressure shown
on unit nameplate. To prevent injury
or death due to instantaneous
release of high pressure water, relief
valves should be field supplied on
water
piping. Supply water
connection may require a backflow
preventer to prevent supply makeup
water from backing up into the public
water system.
WARNING
WATER FREEZING
Failure of the condenser due to
freezing will allow water to enter the
refrigerant circuit and will cause
extensive damage to the refrigerant
circuit components. Any damage to
the equipment as a result of water
freezing in the condenser is excluded
from
coverage under AAON
warranties and the heat exchanger
manufacturer warranties.
WARNING
PVC (Polyvinyl Chloride) and CPVC
(Chlorinated Polyvinyl Chloride) are
vulnerable to attack by certain
chemicals. Polyolester (POE) oils
used
with R-410A and other
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