AAON RQ NextGen Series, Installation Operation & Maintenance

Page: 37 / 108

37
Variable Speed Compressor Supplement
(V83980).
Table 5 - Single Circuited Variable Speed
Compressor Frequency Range
Model (RQ)
Compressor Range
(rpm)
A, B 900-5000 rpm
Thermostat Control Wiring
If a thermostat is used for unit control, locate
thermostat on an inside wall 1.2-1.5 meters
(4-5 feet) above the floor where it will not be
subjected to drafts, sun exposure, or heat
from electrical fixtures of appliances. Control
wiring must deliver adequate voltage to
components to assure proper operation.
Control voltage returning from controller
circuit must be a minimum of 21 VAC. To
assure proper wiring use the following chart
to determine the allowable wiring distances.
Table 6 - Control Wiring
Wire Size
(Stranded) - Copper
Conductors Only
Total Wire Distance
Allowable
20 AWG 60.96 m 200 ft
18 AWG 106.7 m 350 ft
16 AWG 152.4 m 500 ft
14 AWG 228.6 m 750 ft
12 AWG 381.0 m 1250 ft
Take the total wire distance allowable and
divide by the number of wires to be
connected. This indicates the distance
allowable for that size wire. The wiring to the
unit must not exceed the total wire distance
allowable. If the voltage at the connectors is
less than 21 VAC, isolation relays must be
installed. If under external control 21 VAC
must be field verified.
All external devices must be powered via a
separate external power supply.
Example:
A total of 8 wires must be pulled 75ft to
control the unit. What size wire must be
used?
According to the Table 4, 16 AWG allows for
63ft (500 ft/8 wires) and 14 AWG allows for
94ft (750 ft/8 wires). Thus, 14 AWG must be
used.
Condensate Drain Piping
2-6 ton units are equipped with one
condensate drain pan connection on the left
side of the unit. P-trap must be field provided
and installed.
All drain connections must be used and
individually trapped to ensure a minimum
amount of condensate accumulation in the
drain pans. ABS type cement must be used to
join the drain pipe connections.
Note: The drain pan connections are 2.5 cm
(1”) MPT fitting.
Drainage of condensate directly onto the roof
may be acceptable in certain areas, refer to
local codes. If condensate is to drain directly
onto the roof a small drip pad must be placed
below the drain to protect the roof from
possible damage.
If condensate is piped into the building
drainage system, the drain pipe must
penetrate the roof external to the unit itself.
The drain line must be pitched away from the
unit at least 1/8 inch per foot. On longer runs
an air break must be used to ensure proper
drainage.