Nortek T4QE - Application Notes & Charging Charts

8
Application Notes & Charging Charts
(Cooling Mode Only)
     
refrigerant under high pressure. Always use safe
and environmentally sound methods when handling
refrigerant handling or servicing the unit. Review
the factory literature and safety warnings prior to
servicing.
• Whenrepairingsystemleaks,alwaysuseanitrogen
(inert) gas to protect the refrigerant system and pressure
check the repair before re-charging. Always replace
the filter-dryers when performing any repair to the
refrigeration system with one capable of acid removal.
After completing the repairs, evacuate the system to
350 - 500 microns and weigh in the refrigerant to the
amount specified on the unit rating label.
• Chargingchartsarevalidforavarietyofindoor,return
air conditions and are most influenced by the outdoor
ambient temperature, outdoor fan operation and the
unit operating voltage. Before using these charts, make
sure the unit is in a stable operating mode. As shown in
Figure 3, Figure 4 (page 9), Figure 5 (page 9),
Figure 6 (page 10), and Figure 7 (page 10) the
ideal system sub-cooling can vary over the range of
operation. Reference the charts to determine the ideal
amount of sub-cooling for a given liquid pressure. Units
charged to other values will not perform at the rated unit
efficiency (EER) or rated Coefficient of Performance
(COP) in heating mode.
• Toinspectasystemsoperationusingqualityinstruments,
match the measured liquid temperature to the units
chart. The measured liquid pressure reading should
be within 3% of the charts value for most installations.
• Forsystemsthatareoperatingwithmorethana5%
deviation, inspect the unit for the proper voltage and
phase balance and the refrigeration system for leaks.
• Unitsthatareoperatingatlessthen95%ofthenominal
voltage or with a 2% phase imbalance may see a more
significant deviation than the amount stated above.
• DO NOT use the charts in systems that have a fan cycling
under low-ambient control. Refer to the low-ambient kit
instructions for more information. (If applicable)
Figure 3. Charging Chart for 2 Ton Models

90 95 100 105 110 115 120 125130
Liquid Temperature (° F)
Liquid Pressure (psig)
75
80
85
200
220
240
260
280
300
320
340
360
380
400
420
440
460
480
500
520
540
560
580
600
135
Remove refrigerant if above curve
Add refrigerant if below curve
T4QE-024KA CHARGING CHART - COOLING