Mitsubishi Electric City Multi PQHY-P-YLM-A1 Manuel D'installation page 9

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[Fig. 9.2.3]
<A> When the piping (from the twinning pipe) exceeds 2 m [6 ft], include 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 damaging the compressor.
(for PQHY-P series)
2 m [6 ft]
<B> Example of piping connection (for PQHY-P series)
E
F
[Fig. 9.2.4]
<A> Install the piping so that oil will not accumulate in the stopped heat source unit. (both the liquid and the gas side for PQHY-P series,
the high-pressure side only for PQRY-P series)
unit 1
1.
C
D
The NG example shows that oil accumulates because the units are installed on a reverse gradient while unit 1 is in operation, and unit 2 is stopped.
unit 1
2.
unit 1
h1
h1 = 0.2 m (7-7/8 in) max
The NG example shows that oil accumulates into unit 1 while unit 2 is in operation, and unit 1 is stopped. Vertical pipe height (h) should be 0.2 m (7-7/8 in) or below.
D
A
E
G
unit 2
A
unit 2
unit 2
9.2
B
C
A : Indoor unit
B : Trap (gas pipe only)
C : Within 2 m [6 ft]
D : Twinning pipe
E : Field-supplied piping
F : Twinning kit
G : Straight pipe length that is 500 mm [19-11/16 in] or more
unit 1
C
D
unit 1
h1
h1 > 0.2 m (7-7/8 in)
D
A
unit 2
B
unit 2
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