McQuay MDB075B Manual page 93

Field Piping
To ensure satisfactory operation and performance, the following points should be noted for the field piping
arrangements of the complete refrigerant cycle.
a) Liquid loops or oil traps must be provided according to the position of the outdoor and the indoor units
(depending on whether the indoor unit is above or below the outdoor unit).
b) Field supplied filter dryer should be provided as close to the expansion valve(s) of the indoor unit
(evaporator) as possible.
c) Field supplied sight glass must be assembled and mounted next to filter dryer.
Maximum Pipe Length And Maximum Number Of Bends
When the pipe is too long, the required refrigerant quantity increases. Both the capacity and reliability drops
as a result. As the number of bends increases, system piping resistance to the refrigerant flow increases,
thus lowering the cooling capacity and the compressor may become defective. If the height difference
between the evaporator and the condenser is excessive, the cooling capacity drops, the lubricating oil return
is retarded, affecting the compressor efficiency adversely.
Always choose the shortest piping path and follow the recommendations as shown below :
Model
MMC 075B
MMC 100B/BR
MMC 125B/BR
MMC 075C/CR
MMC 100C
MMC 150C
CAUTION:
1) Our guarantee on the performance of our air-conditioners is strictly revoked if the height, length
and/or the number of bends of the refrigerant piping system installed is beyond the limit above.
2) Bendings must be carefully made so as not to crush the pipe. Use a pipe bender to bend a pipe
as far as possible.
Max. Elevation,
m (ft.)
25(82.0)
25(82.0)
25(82.0)
25(82.0)
25(82.0)
25(82.0)
Maximum Allowable Piping Length & Elevation Difference
Max. Length, Max. Total Length,
m (ft)
20 (65.6)
20 (65.6)
20 (65.6)
20 (65.6)
20 (65.6)
20 (65.6)
92
Max. of
m (ft.) Bends
45(147.6)
45(147.6)
45(147.6)
45(147.6)
45(147.6)
45(147.6)
8
8
8
8
8
8