Refrigerant Piping Connections - York MKC 12S Technical Manual

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7 - Refrigerant piping connections

Make piping runs as short as possible and avoid all
unnecessary changes in direction or elevation.
To prevent heat loss, the two lines must be insulated
s e p a r a t e l y.
Use an appropriate bending tool to form curves and avoid
flattening the refrigerant tubes.
Fix piping with pipe clamps and make sure that any eventual
pipe vibrations cannot be transmitted to the building structure.
Use refrigeration quality piping only with an operating pres-
sure rating of at least 30 bars. N e v e r use ordinary «plum-
bing» quality piping : you MUST use special de-oxidised,
dehydrated, refrigerant quality copper piping.
Pipe lengths
• Maximum piping lengths
Unit size 12
D (m) 15
L (m) 18
H (m) 12
Note: Where the difference in elevation between the indoor
unit and the outdoor unit is greater than 5 metres, install
an oil trap every 5 metres.
The suction line must have a 2% gradient up to the compressor
on horizontal sections.
Where piping lengths are unusually long and include a large
number of oil traps, it may be necessary to adjust the compres-
sor oil charge.
• Refrigerant charge to be added per extra metre of
piping length when more than 7.5 m.
Unit size 12
g/m 15
Refrigerant piping connections (FLARE connections)
To avoid alteration of unit capacities, make sure that piping
lengths and changes in elevation are kept to a strict minimum.
Before connecting the refrigerant lines, follow the procedures
below (if pre-charged connection lines are not supplied) :
- Select copper pipe diameters according to the size of unit to
be installed.
- Install the refrigeration lines, making sure that no foreign
bodies get inside the piping.
- Install the flare connectors and flare the ends of the pipes.
- Evacuate the piping. This operation, which should last at
least 15 minutes or even longer if there are large piping
lengths and changes in elevation, should be followed by a
leak test. To this effect, when the piping has been evacua-
ted, close the pressure guage tap, note the value on the
guage, then wait for 15 minutes. If the needle moves, there
is a leak in the system. Make the necessary adjustments or
repairs and repeat this procedure until the needle no longer
m o v e s .
- Open the service valves and top up the refrigerant charge if
n e c e s s a r y.
18 25
15 22
18 25
12 20
18 25
40 40
Insulation
Minimum thickness 6 mm
Heat pump
(discharge)
Heat pump
Liquid
D
Cooling
L
Low pressure
High pressure
Manifold
Pressure
tap
Outdoor unit
Gas line
Liquid line
R22
L
Gas
Cooling
(suction)
Heat pump
(discharge)
Heat pump
Liquid
Gas
Cooling
Cooling
(suction)
Gas valve
Liquid valve
Indoor unit
7