Air Evacuation & Adding Refrigerant
Page 45 mrcool.com
10. Watch the pressure gauge for 1 minute to ensure
that there are no changes in pressure. The
pressure gauge should read slightly higher
atmospheric pressure.
11. If the pressure gauge reads slightly higher than
atmospheric pressure, then remove the charge
hose from the service port.
12. Remove all of the remaining valve caps. Then,
using an Allen/hexagonal wrench, fully open the
valves. If installing a 3, 4, or, 5 zone multi-zone
condenser, open the air handler connection
point valves first. Then open the high
pressure and low pressure main valves.
13. Reinstall and tighten all of the valve caps by hand.
You may tighten them further if necessary using a
torque wrench.
Open all of the valves gently. When opening
the valve stems, turn the Allen/hexagonal
wrench until it hits against the stopper.
DO NOT try to force the valve to open
beyond the stopper, as this could damage
the valve and/or cause it to leak.
IMPORTANT
Note on Adding Additional Refrigerant
Some systems require additional refrigerant to be
charged into the system depending upon the length
of the refrigerant piping. Standard pipe length varies
depending upon the local regulations of the
country/region the unit is being installed. For
example, in North America, the standard pipe length
is 25 ft (7.5 m). In other areas, the standard pipe
length is 16 ft (5 m). Any additional refrigerant should
be charged into the system from the service port on
the outdoor unit’s low pressure valve. The additional
refrigerant to be charged can be calculated using the
information and formula found in the table below.
For R290 refrigerant unit, the total amount of refrigerant to be charged is no more than:
387g (<=9000 Btu/h), 447g (>9000 Btu/h and <=12000 Btu/h), 547g (>12000 Btu/h and <=18000 Btu/h),
632g (>18000 Btu/h and <=24000 Btu/h).
ADDITIONAL REFRIGERANT PER PIPE LENGTH
Connective
Pipe
Length (m)
Air
Purging
Method
Additional Refrigerant
≤ Standard
pipe length
Vacuum
Pump
N/A
> Standard
pipe length
Vacuum
Pump
Liquid Side: Ø 0.25 in (ø 6.35 mm)
R32:
(Pipe length – standard length) x 12 g/m
(Pipe length – standard length) x 0.13 oZ/ft
R290: R290:
(Pipe length – standard length) x 10 g/m
(Pipe length – standard length) x 0.10 oZ/ft
Liquid Side: Ø 0.375 in (ø 9.52 mm)
R32:
(Pipe length – standard length) x 24 g/m
(Pipe length – standard length) x 0.26 oZ/ft
(Pipe length – standard length) x 18 g/m
(Pipe length – standard length) x 0.19 oZ/ft
R410A: R410A:
(Pipe length – standard length) x 15 g/m
(Pipe length – standard length) x 0.16 oZ/ft
(Pipe length – standard length) x 30 g/m
(Pipe length – standard length) x 0.32 oZ/ft
R22:
(Pipe length – standard length) x 20 g/m
(Pipe length – standard length) x 0.21 oZ/ft
R22:
(Pipe length – standard length) x 40 g/m
(Pipe length – standard length) x 0.42 oZ/ft
DO NOT under any circumstances mix
refrigerant types.
CAUTION
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