Piping Considerations - Daikin ARQ Installation Manual

Piping Considerations

1. All units should be connected to supply and return piping in a
two-pipe reverse return configuration. A reverse return system is
inherently self-balancing and requires only trim balancing where
multiple quantities of units with different flow and pressure drop
characteristics exist in the same loop. Check for proper water
balance by measuring differential temperature reading across the
water connections. To insure proper water flow, the differential flow
should be 10°F to 14°F (5°C to 8°C) for units in cooling mode.
A direct return system may also work acceptably, but proper water
flow balancing is more difficult to achieve and maintain.
2. The condenser water or loop piping can be steel or copper.
3. Supply and return runouts usually join the unit via short lengths of
high pressure flexible hose which are sound attenuators for both
unit operating noise and hydraulic pumping noise. One end of the
hose should have a swivel fitting to facilitate removal for service.
Hard piping can also be brought directly to the unit. This option is
not recommended since no vibration or noise attenuation can be
accomplished. The hard piping must have unions to facilitate unit
removal.
4. Some flexible hose threaded fittings are supplied with sealant
compound. If not, apply Teflon tape to assure a tight seal.
Note: Do not over-torque fittings. The maximum
torque without damage to fittings is 30 foot pounds.
If a torque wrench is not available, use as a rule of
thumb, finger-tight plus one quarter turn.
5. Supply and return shutoff valves are required at each conditioner.
The return valve is used for balancing and should have a "memory
stop" so that it can always be closed off but can only be reopened
to the proper position for the flow required.
6. No unit should be connected to the supply and return piping until
the water system has been cleaned and flushed completely. After
the cleaning and flushing has taken place, the initial connection
should have all valves wide open in preparation for water system
flushing.
7. Condensate drain piping can be steel, copper or PVC or CPVC.
8. The condensate drain hose must be trapped. The hose must be
pitched away from the unit not less than 1⁄4" per foot. The unit
drain pan has a 7/8 inch O.D. drain connection to accommodate
the condensate drain hose.
Page 20 of 42 Self-Contained WSHP Unit Ventilator Models ARQ, ERQ, GRQ
Figure 36: Condensate Disposal Trapping Detail
Drain Pan (Left End)
A
B
Table 10: Condensate Drain Trap & Static Pressure
Standard Static Pressure
High Static
9. Do not locate any point in the drain system above the drain connection
of any unit.
10. Automatic flow controlled devices must not be installed prior to
system cleaning and flushing.
11. A high point of the piping system must be vented.
12. Check local code for the need for dielectric fittings.
C
7/8" I.D. Clear Plastic
A B
1¼" 5/8" 2¾"
1½" 3/4" 3⅛"
C
IM 1083