Daikin RXYQ96PYDN Service Manual page 239

Test Operation
<Air tight test>
<Vacuum drying>
NOTE:
If any moisture enters the piping, use the following precautions:
After evacuating the system for 2 hours, pressurize the system to 7.25 psi (vacuum break) with
nitrogen gas and evacuate the system again using the vacuum pump for 1 hour to –14.6 psi or less
(vacuum drying). If the system cannot be evacuated to –14.6 psi within 2 hours, repeat the
operation of vacuum break and vacuum drying.
Then, after leaving the system in vacuum for 1 hour, confirm that the vacuum gauge does not rise.
10.2.4 Pipe Insulation
224
Pressurize the liquid pipe, suction gas pipe, HP/LP gas pipe and equalizer pipe from the service
ports of each shutoff valve to 478 psi (do not pressurize more than 478 psi). If the pressure does
not drop within 24 hours, the system passes the test.
If there is a pressure drop, check for leaks, make repairs and perform the airtight test again.
Evacuate the system from the liquid pipe, suction gas pipe, HP/LP gas pipe and equalizer pipe
shutoff valve service ports by using a vacuum pump for more than 2 hours and bring the system
to –14.6 psi or less. After keeping the system under that condition for more than 1 hour, check if
the vacuum gauge rises or not. If it rises, the system may either contain moisture inside or have
leaks.
If working while it is raining, condensation may form on the inside of the pipes.
Insulation of pipes should be done after performing the steps described in Section 10.2.3 Air
Tight Test And Vacuum Drying.
Always insulate the liquid piping, the HP/LP gas piping, the gas piping, the equalizer pipe
(between the outside units for the outdoor multi system) and these pipe connections.
Failing to insulate the pipes may cause leaking or burns.
IMPORTANT:
BE SURE to insulate the HP/LP gas piping as the suction pipe because the suction gas follows
in the HP/LP gas piping when the system is entirely in cooling mode.
BE SURE to use the insulation that is designed for use with HVAC Systems.
Reinforce the insulation on the refrigerant piping according to the installation environment.
Condensation might form on the surface of the insulation. Refer to the below.
Ambient temperature : 86°F, humidity : 75% to 80% RH : min. thickness : 9/16 inches.
If the ambient temperature exceeds 86°F and the humidity 80% RH, then the minimum
thickness is 3/4 inches.
See the Engineering data book for detail.
If there is a possibility that condensation on the shutoff valve might drip down into the indoor unit
through gaps in the insulation and piping because the outside unit is located higher than the
indoor unit. This must be prevented by caulking the connections. (Refer to figure 26)
The piping lead-out hole lid should be attached after opening a knock hole. (Refer to figure 27)
If small animals or foreign materials enter the unit through the piping lead-out hole, close the
hole with blocking material (procured on site) after completion of 10.2.6 Additional Refrigerant
Charge and Check Operation. (Refer to figure 30)
SiUS34-801A_b
VRVIII R-410A Heat Recovery 60Hz