Charge Verification - Approach Method - Ahri Testing (Fin/Tube Coil); Compressor Controls - Lennox LGH180H Installation Instructions Manual

F-Charge Verification - Approach Method - AHRI Testing
(Fin/Tube Coil)
1- Using the same thermometer, compare liquid
temperature to outdoor ambient temperature.
Approach Temperature = Liquid temperature (at
condenser outlet) minus ambient temperature.
2- Approach temperature should match values in table
21. An approach temperature greater than value
shown indicates an undercharge. An approach
temperature less than value shown indicates an
overcharge.
3- The approach method is not valid for grossly over or
undercharged systems.
guide for typical operating pressures.
TABLE 21
APPROACH TEMPERATURES - FIN/TUBE COIL
Liquid Temp. Minus Ambient Temp.
L Series
Unit
1st Stage 2nd Stage
9°F + 1 9°F + 1
156H Std.
(5.0°C +0.5) (5.0°C +0.5)
156H 6°F+1 6°F+1
Reheat (3.3°C+0.5) (3.3°C+0.5)
6°F + 1 6°F + 1
180H Std.
(3.3°C +0.5) (3.3°C +0.5)
180H 4°F + 1 4°F + 1
Reheat (2.2°C +0.5) (2.2°C +0.5)
5°F + 1 6.5°F + 1
180U
(2.8°C +0.5) (3.6°C +0.5)
6°F + 1 6°F + 1
210H Std.
(3.3°C +0.5) (3.3°C +0.5)
210H 4°F + 1 4°F + 1
Reheat (2.2°C +0.5) (2.2°C +0.5)
6°F + 1 6°F + 1
240H Std.
(3.3°C +0.5) (3.3°C +0.5)
240H 4°F + 1 4°F + 1
Reheat (2.2°C +0.5) (2.2°C+0.5)
4°F + 1 6.5°F + 1
240U
(2.2°C +0.5) (3.6°C +0.5)
5°F+1 5°F+1
300S Std.
(2.8°C+0.5) (2.8°C+0.5)
300S 3°F+1 3°F+1
Reheat (1.7°C+0.5) (1.7°C+0.5)
LGH/LCH156, 180, 210, 240, 300S
9 through 20
Use tables as a
3rd Stage 4th Stage
11°F + 1
NA
(6.1°C +0.5)
11°F+1
NA
(6.1°C+0.5)
6°F + 1
NA
(3.3°C +0.5)
6°F + 1
NA
(3.3°C +0.5)
NA NA
7°F + 1
NA
(3.9°C +0.5)
7°F + 1
NA
(3.9°C +0.5)
7°F + 1 7°F + 1
(3.9°C +0.5) (3.9°C +0.5)
8°F + 1 8°F + 1
(4.4°C +0.5) (4.4°C +0.5)
NA NA
8°F+1 8°F+1
(4.4°C+0.5) (4.4°C+0.5)
8°F+1 8°F+1
(4.4°C+0.5) (4.4°C+0.5)
G-Compressor Controls
See unit wiring diagram to determine which controls are
used on each unit.
1- High Pressure Switch (S4, S7, S28, S96)
The compressor circuit is protected by a high
pressure switch which opens at 640 psig + 10 psig
(4413 kPa + 70 kPa) and automatically resets at 475
psig + 20 psig (3275kPa + 138 kPa).
2- Low Pressure Switch (S87, S88, S97, S98)
The compressor circuit is protected by a low
pressure switch. Switch opens at 40 psig + 5 psig
(276 + 34 kPa) and automatically resets at 90 psig
+ 5 psig (621 kPa + 34 kPa).
3- Crankcase Heater (HR1, HR2, HR5, HR11)
Units have compressors which contain a belly band
compressor oil heater which must be on 24 hours before
running compressors. Energize by setting thermostat so
that there is no cooling demand, to prevent compressor
from cycling, and apply power to unit.
4- Low Ambient Pr. Sw. (S11, S84, S85, S94)
Switch maintains adequate discharge pressure by
de-energizing condenser fan when liquid pressure
falls below 240 psig +10 (1655 kPa+69). Switch
closes to energize condenser fan when pressure
rises to 450 psig +10 (3103kPa + 69).
All three condenser fans are energized on a Y1
cooling demand and continue to operate when Y2
demand is initiated. See figure 22.
Condenser fans 2 and 3 are de-energized when
outdoor temperature drops below 55°F (13°C). S11,
S84 and S85 pressure switches (in refrigerant circuits
1, 2 and 3 respectively) are wired to the Unit
Controller.
Condenser fan 1 is cycled by S11, S84 and S85
pressure switches when outdoor temperature drops
below 55°F (13°C).
156 CONDENSER FANS
Page 38
156
COND.
FAN 1
COND.
FAN 2
COND.
FAN 3
FIGURE 22