13
Twinning on the outdoor unit side
Twinning pipe
±
15
°
The tilt angle of the twinning pipe should
be within
±
15
°
with the horizontal plane.
Note: See the following drawing for the fitting
position of the twinning pipe.
The tilt angle of the twinning pipe
The tilt angle of the twinning pipe must be within ±15° with the horizontal plane.
Tilting the twinning pipe more than specified will cause damage to the unit.
The length of the straight part of the pipe before the branching
For the twinning kit, always use the accessory piping parts.
The length of the straight part of pipe connected in front of the
twinning pipe must be 500 mm [19-11/16 in.] or longer.
(Connect the field piping so that the length of the straight part
of pipe connected in front of the twinning pipe can be 500 mm
[19-11/16 in.] or longer.)
If the length is less than 500 mm [19-11/16 in.], it will cause damage
to the unit.
To Indoor unit
Less than 2 m [6 ft.]
To Indoor unit
2m [6 ft.]
200 mm [7-7/8 in.]
or over
Trap
(gas pipe only)
Precautions for outdoor unit combinations
<2 m [6 ft.] or less>
<More than 2 m [6 ft.]>
Caution:
Do not install traps other than the ones between outdoor units described on a separate sheet to prevent oil backflow and compre
ssor start-up failure.
Do not install solenoid valves to prevent oil backflow and compressor start-up failure.
Do not install a sight glass because it may show improper refrigerant flow.
If a sight glass is installed, inexperienced technicians that use the glass may overcharge the refrigerant.
•
•
•
<A> Install the piping so that oil will not accumulate in the stopped outdoor unit.
1.
unit 1
unit 2
unit 3
unit 1
unit 2
unit 3
unit 1
unit 2
unit 3
The NG example shows that oil accumulates because the units are installed on a reverse gradient while unit 1 is in operation, and unit 3 is stopped.
2.
unit 1
unit 2
unit 3
unit 1
unit 2
unit 3
h1
h1 = 0.2 m (7-7/8 in) max
h1
h1 > 0.2 m (7-7/8 in)
The NG example shows that oil accumulates into units 1 and 2 while unit 3 is in operation, and units 1 and 2 are stopped.
Vertical pipe height (h) should be 0.2 m (7-7/8 in) or below.
3.
unit 1
unit 2
unit 3
unit 3
h2
h2 = 0.1 m (3-15/16 in) max
unit 1
unit 2
unit 3
h2
h2 > 0.1 m (3-15/16 in)
The NG example shows that oil accumulates into unit 1 while unit 3 is in operation, and unit 1 is stopped. Vertical pipe height (h) should be 0.2 m (7-7/8 in) or below.
4.
unit 1
unit 2
h2 = 0.1 m (3-15/16 in) max
h2
h2 > 0.1 m (3-15/16 in)
The NG example shows that oil accumulates into unit 3 while unit 1 is in operation, and unit 3 is stopped. Vertical pipe height (h) should be 0.2 m (7-7/8 in) or below.
<B> When the piping on the outdoor unit side (from the twinning pipe) exceeds 2 m [6 ft], ensure a trap (
gas pipe only
) within 2 m [6 ft].
Make sure the height of the trap is 200 mm [7-7/8 in] or more.
If there is no trap, oil can accumulate inside the pipe, causing a shortage of oil and possible damage to the compressor.
To Indoor unit
To Indoor unit
Twinning pipe
Twinning pipe
Twinning pipe
Twinning pipe
Downward slope
Upward slope
unit 3
unit 1
unit 2
h2
Summary of Contents for BDT CITY MULTI
Page 41: ...41 S SERIES OUTDOOR UNIT WIRING INPUTS AND OUTPUTS CITY MULTI ONLY ...
Page 42: ...42 INDOOR UNIT WIRING INPUTS AND OUTPUTS CITY MULTI ONLY INPUTS AND OUTPUTS Continued ...
Page 44: ...44 RECOMMENDED M NET WIRING PROCEDURE CABLE LIMITATIONS AND SYSTEM EXAMPLES ...
Page 47: ...47 ...
Page 48: ...48 BASIC SYSTEM M NET WIRING AND ADDRESSING EXAMPLE M NET ADDRESSING Continued ...
Page 63: ...63 DIP SWITCHES INDOOR UNITS ...
