036-21365-003-D-1105
8 Unitary Products Group
SC provides a 90 second bypass of the low pressure
switch LP to prevent nuisance lockouts during unit start-
up.
A malfunction light (24V, 2 A max. resistive load) can be
energized through SC, by connecting the light between
terminals X and B on TB1. Terminal X will energize when
SC locks out.
3. Unit is equipped with an anti-short cycle timer to prevent
two successive compressor starts within 5 minutes. If the
compressor fails to start with a call for cooling and SC is
not locked out, wait at least 6 minutes for the anti-cycle
timer to reset.
NOTE:
To reset the unit after a lockout:
A. Turn the system switch on the thermostat to the
“OFF” position and back to the “COOL” position.
OR
B. Increase the set point of the room thermostat above
the temperature in the conditioned space and return
it to its original setting.
If the unit continues to be shut down by one of its safety con-
trols, service should be called to determine the cause of the
problem. Repeatedly resetting the lockout circuit may dam-
age the unit.
TABLE 7: SUCTION LINE DATA
1
,
2
Model
Designation
Nominal Capacity
(Tons)
Refrigerant
Flow Rate
3
(Lbs./Min.)
Type L
Copper tubing
(Inches O.D.)
Refrigerant Gas
Velocity
(FT./Min.)
Friction
Loss
4
,
5
(PSI/100 Ft.)
HA120 10 30 1-3/8 2280 2.8
1
All horizontal suction lines should be pitched at least 1 inch every 20 feet in the direction of the refrigerant flow to aid the return of oil to the compres-
sor.
2
Every vertical suction riser greater than 25 feet in height should have a “P” trap at the bottom to facilitate the return of oil to the compressor. Use short
radius fittings for these traps.
3
Based on Refrigerant-22 at the nominal capacity of the condensing unit, a suction temperature of 40º F and a liquid temperature of 105º F.
4
Although suction lines should be sized for a friction loss equivalent to a 2º F change in saturation temperature (or approximately 3 psi), sizing the
lines for the proper return of oil is more important.
5
These friction losses do not include any allowances for valves or fittings.
TABLE 8: LIQUID LINE DATA
Model
Nominal
Capacity
Tons
Refrigerant
Flow Rate
1
(Lbs/Min.)
1
Based on Refrigerant-22 at the nominal capacity of the con-
densing unit, a liquid temperature of 105º F and a suction tem-
perature of 40º F.
Type L
Copper Tubing
(Inches O.D.)
Pressure Drop
2
2
These friction losses do not include any allowances for a
strainer, filter-drier, solenoid valve, isolation valve or fittings.
Friction
3
(PSI/100 Ft.)
3
The total pressure drop of the liquid line for both friction and ver-
tical rise must not exceed 40 PSI. if the pressure drop exceeds
40 PSI, the liquid refrigerant could flash before it reaches the
expansion valve. This flashing will not only cause erratic valve
operation and poor system performance, but could also dam-
age the expansion valve.
Vertical Rise
(PSI/Ft.)
HA120 10 30 5/8 5.8 0.5
TABLE 9: REFRIGERANT-22 LINE CHARGE
1
1
Charges are based on 40º F suction temperature and a 105º F
liquid temperature.
Liquid Line
2
Inches, O.D.
2
Type “L” copper tubing.
5/8 0.113 lb./ft.
Suction Line
2
Inches, O.D.
1-3/8 0.013 lb./ft.
NOTE: Add the operating charge of the condensing unit, the evaporator coil
and the refrigerant lines to determine the total refrigerant charge of the
system.
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