Lennox LCH036 Installation Instructions Manual page 117

C-R410A Refrigerant
Units charged with R410A refrigerant operate at much
higher pressures than R22. The expansion valve and
liquid line drier provided with the unit are approved for use
with R410A. Do not replace them with components
designed for use with R22.
R410A refrigerant is stored in a pink cylinder.
IMPORTANT
Mineral oils are not compatible with R410A. If oil
must be added, it must be a polyol ester oil.
Manifold gauge sets used with systems charged with
R410A refrigerant must be capable of handling the higher
system operating pressures. The gauges should be rated
for use with pressures of 0-800 on the high side and a low
side of 30" vacuum to 250 psi with dampened speed to
500 psi. Gauge hoses must be rated for use at up to 800
psi of pressure with a 4000 psi burst rating.
D-Refrigerant Charge and Check
WARNING-Do not exceed nameplate charge under
any condition.
This unit is factory charged and should require no further
adjustment. If the system requires additional refrigerant,
reclaim the charge, evacuate the system, and add
required nameplate charge.
NOTE - System charging is not recommended below
60_F (15_C). In temperatures below 60_F (15_C), the
charge must be weighed into the system.
If weighing facilities are not available, or to check the
charge, use the following procedure:
IMPORTANT - Charge unit in standard cooling mode.
1- Make sure outdoor coil is clean. Attach gauge
manifolds and operate unit at full CFM in cooling
mode with economizer disabled until system
stabilizes (approximately five minutes). Make sure all
outdoor air dampers are closed.
2- Check each system separately with all stages
operating. Compare the normal operating pressures
(see tables 5 - 9) to the pressures obtained from the
gauges. Check unit components if there are
significant differences.
3- Measure the outdoor ambient temperature and the
suction pressure. Refer to the appropriate circuit
charging curve to determine a target liquid
temperature.
Note - Pressures are listed for sea level applications.
4- Use the same thermometer to accurately measure the
liquid temperature (near the liquid service tap).
D If measured liquid temperature is higher than
the target liquid temperature, add refrigerant to
the system.
D If measured liquid temperature is lower than
the target liquid temperature, recover some
refrigerant from the system.
5- Add or remove charge in increments. Allow the
system to stabilize each time refrigerant is added or
removed.
6- Continue the
temperature
temperature. Do not go below the target liquid
temperature when adjusting charge. Note that
suction pressure can change as charge is adjusted.
7- Example LGH/LCH242H Circuit 1: At 95°F outdoor
ambient and a measured suction pressure of
130psig, the target liquid temperature is 98°F. For a
measured liquid temperature of 106°F, add charge in
increments until measured liquid temperature agrees
with the target liquid temperature.
Page 17
process until measured
agrees with the target
liquid
liquid