D–EIMWC00808-16HU - 28/64
Daikin centrifugal units have relief valve settings of 180 psi, 200 psi, and 225 psi, and resultant valve discharge capacities
of 68.5 # air/min, 75.5 # air/min, and 84.4 # air/min respectively.
Using the ASHRAE formula and basing calculations on the 225 psi design yields a conservative pipe size, which is
summarized in Table 9. The table gives the pipe size required
per relief valve
. When valves are piped together, the
common piping must follow the rules set out in the following paragraph on common piping.
Table 9. Relief Valve Piping Sizes
Equivalent length (ft)
2.2
18.5
105.8
296.7
973.6
4117.4
Pipe Size inch (NPT)
1 1/4
1 ½
2
2 1/2
3
4
Moody Factor
0.0209
0.0202
0.0190
0.0182
0.0173
0.0163
NOTE: A 1-inch pipe is too small for the flow from the valves. A pipe increaser must always be installed at the valve outlet.
Common Piping
According to ASHRAE Standard 15, the pipe size cannot be less than the relief valve outlet size. The discharge from
more than one relief valve can be run into a common header, the area of which cannot be less than the sum of the areas
of the connected pipes. For further details, refer to ASHRAE Standard 15. The common header can be calculated by
the formula:
DCommon
D
D
Dn
=
+
1
2
2
2
2
0 5
....
.
The above information is a guide only. Consult local codes and/or latest version of ASHRAE Standard 15 for sizing
data.
Electrical
Wiring, fuse and wire size must be in accordance with the National Electric Code (NEC). Standard NEMA motor
starters require modification to meet Daikin specifications. Refer to Daikin Specification R35999901 or Daikin Product
Manual PM DWSC/DWDC.
Important
: Voltage unbalance not to exceed 2% with a resultant current unbalance of 6 to 10 times the voltage
unbalance per NEMA MG-1, 1998 Standard. This is an important restriction that must be adhered to.
Power Wiring
WARNING
Qualified and licensed electricians must perform wiring. Shock hazard exists.
Power wiring to compressors must be in proper phase sequence. Motor rotation is set up for clockwise rotation facing
the lead end with phase sequence of 1-2-3. Care must be taken that the proper phase sequence is carried through the
starter to compressor. With the phase sequence of 1-2-3 and L1 connected to T1 and T6, L2 connected to T2 and T4,
and L3 connected to T3 and T5, rotation is proper. See diagram in terminal box cover.
The Daikin start-up technician will determine the phase sequence.
CAUTION
Connections to terminals must be made with copper lugs and copper wire.
Care must be taken when attaching leads to compressor terminals.
CAUTION
Before any installation and connection work, the system must be switched off and secured. After
switching off the unit, when an inverter is installed, the intermediate circuit capacitors of the
inverter are still charged with high voltage for a short period of time. The unit can be worked on
again after it has been switched of for 5 minutes.
