
23
Checking Liquid Sub-cooling
1.
Measure the temperature of the
liquid
line
as it leaves the condenser coil.
2.
Read the gauge pressure reading of the
liquid line
close to the point where the
temperature was taken. You must use liquid
line pressure, as it will vary from discharge
pressure due to condenser coil pressure
drop.
3.
Convert the pressure obtained in Step 2 to
a
saturated
temperature
using
the
appropriate refrigerant temperature-pressure
chart.
4.
Subtract the measured liquid line
temperature in Step 1 from the saturated
temperature in Step 3 to determine the liquid
sub-cooling.
5.
Compare calculated sub-cooling to
TABLE 7 for the appropriate unit type and
options.
Checking Evaporator Superheat
1.
Measure the temperature of the
suction
line
close to the compressor.
2.
Read gauge pressure at the
suction line
close to the compressor.
3.
Convert the pressure obtained in Step 2 to
a
saturated
temperature
using
the
appropriate refrigerant temperature-pressure
chart.
4.
Subtract the saturated temperature in Step
3
from
the
measured
suction
line
temperature in Step 1 to determine the
evaporator superheat.
5.
Compare calculated superheat to TABLE
7 for the appropriate unit type and options.
Adjusting Sub-cooling and Superheat
Temperatures
The system is
overcharged
if:
1.
the sub-cooling temperature is too high
and
2.
the evaporator is fully loaded (low loads
on the evaporator result in increased sub-
cooling)
and
3.
the evaporator superheat is within the
temperature range as shown in Table 7 (high
superheat results in increased sub-cooling)
Table 7 - Acceptable Refrigeration Circuit
Values
Air-Cooled Cond./Air-Source Heat Pump
Sub-Cooling**
8-15°F / 2-4°F (HP)*
Sub-Cooling with
Hot Gas Reheat**
8-15°F / 2-6°F (HP)*
Superheat***
8-15°F
*In cooling mode operation
**Sub-cooling must be increased by 2°F per
20 feet of vertical liquid line rise for R-410A
***Superheat will increase with long
suction line runs.
Correct an overcharged system by reducing
the amount of refrigerant in the system to
lower the sub-cooling.
The system is
undercharged
if:
1.
The superheat is too high
and
2.
The sub-cooling is too low.
DO NOT OVERCHARGE!
Refrigerant overcharging leads to
excess refrigerant in the condenser
coils resulting in elevated compressor
discharge pressure.
CAUTION
Содержание F1-060
Страница 31: ...31 ...
Страница 33: ...33 Figure 5 Modulating Hot Gas Reheat Piping Diagram with Air Handling Unit below Condensing Unit ...
Страница 36: ...36 Figure 8 Heat Pump Piping Diagram with Indoor Unit above Outdoor Unit ...
Страница 37: ...37 Figure 9 Heat Pump Piping Diagram with Outdoor Unit above Indoor Unit ...
Страница 38: ...38 Figure 10 Heat Pump Piping Diagram with Modulating Hot Gas Reheat and Indoor Unit above Outdoor Unit ...
Страница 39: ...39 Figure 11 Heat Pump Piping with Modulating Hot Gas Reheat and Outdoor Unit above Indoor Unit ...
Страница 40: ...40 Thermostat Installation and Wiring Figure 12 2 Stage Cooling with Electric Heat ...
Страница 41: ...41 Figure 13 2 Stage Cooling with Heat Pump and Electric Heat ...
Страница 42: ...42 Figure 14 2 Stage Cooling and Electric Heat with Hot Gas Reheat and Humidistat ...
Страница 43: ...43 Figure 15 Main Control Board for Units Equipped with Modulating Hot Gas Reheat ...
Страница 45: ...45 Figure 17 5kW Electric Heat ...
Страница 46: ...46 Figure 18 10 kW Electric Heat ...
Страница 47: ...47 Figure 19 15 kW Electric Heat ...
Страница 48: ...48 Figure 20 20 kW Electric Heat ...
Страница 49: ...49 Figure 21 25 kW Electric Heat ...
Страница 55: ...55 ...