Midea V8 Series Manual page 104

V8 Mini R410A VRF 50Hz
 Air conditioner drain piping should be installed separately from waste, rainwater and other drain piping and should not
come into direct contact with the ground.
 Drain piping diameter should be not less than the indoor units' drain piping connection.
 To allow inspection and maintenance, the piping clamps shipped with units should be used to attach drain piping to
indoor units – adhesive should not be used.
 Thermal insulation should be added to drain piping to prevent condensation forming. Thermal insulation should extend
all the way to the connection with the indoor unit.
 Units with drain pumps should have separate drain piping systems from systems that use natural drainage.
5.2 Water Traps
For indoor units with a high negative pressure differential at the outlet of the
drainage pan, a trap should be fitted to the drain piping to prevent poor
drainage and/or water being blown back into the drainage pan. Traps should
be arranged as in Figure 3-5.6. The vertical separation H should be in excess
of 50mm. A plug may be fitted to allow cleaning or inspection.
5.3 Selecting Piping Diameters
Select branch drainage piping (the drain piping connection to each unit) diameters according to indoor unit flow volume
and select main drainage piping diameters according to the combined flow volume of the upstream indoor units. Use a
design assumption of 2 liters of condensate per horsepower per hour. For example, the combined flow volume of three 2HP
units and two 1.5HP units would be calculated as follows:
Combined flow volume
Tables 3-5.1 and 3-5.2 specify the required piping diameters for horizontal and vertical branch piping and for main piping.
Note that main piping should use PVC40 or larger.
Table 3-5.1: Horizontal drain piping diameters
PVC piping
PVC25
PVC32
PVC40
PVC50
PVC63
102
Figure 3-5.5: Drain piping air vents
Vent
= 3 x
+ 2 x
Nominal
diameter (mm)
Slope 1:50
25
32
40
50
63
Figure 3-5.6: Drain piping water traps
2 L/HP/h × 2HP
2 L/HP/h × 1.5HP
Capacity (L/h)
Slope 1:100
39 27
70 50
125 88
247 175 Branch or main piping
473 334
= 18 L/h
Remarks
Branch piping only