Low Ambient Cooling Enhancement - Daikin VRV IV REYQ72TATJA Design Manual

REYQ-TATJA / TAYDA

19. Low Ambient Cooling Enhancement

REYQ72-456TATJA / TAYDA
„ REYQ-T series include a feature for Low Ambient Cooling.
„
„ The function enhances REYQ-T series as follows:
„
• Allows operation to −4ºFDB (−20ºCDB) ambient temperature in cooling mode. (Normal limit is 23ºFDB (−5ºCDB).)
• Operation below 23ºFDB (−5ºCDB) requires the addition of wind covers onto the outdoor unit.*
Application Rules:
• Total connection index of each system is limited to 50-130% when height difference is 0-194 ft. (0-50 m), 80-130% when 194-295 ft. (50-90 m).
• All units on the system must be connected to a Branch Selector Box, Low ambient cooling is only available on indoor unit connected to a single
branch selector box. Single and Multi-port Branch Selector Boxes may be combined on one system but all indoor units connected to a multi branch
selector box will operate as standard without the low ambient cooling function.
• F unction is engaged by a field setting on the outdoor unit (to enable Low Ambient Cooling) and a dip switch setting is necessary on the Single
Branch Selector Boxes BSQ-T series serving the indoor units NOT subject to Low Ambient Cooling requirements.
• During operation below 23ºFDB (−5ºCDB), the available cooling capacity decreases as follows:
14ºFDB (−10ºCDB) - Reduces to 80% of nominal.
5ºFDB (−15ºCDB) - Reduces to 65% of nominal.
–4ºFDB (−20ºCDB) - Reduces to 60% of nominal. (Only applicable to Single-port Branch Selector Boxes)
• The operating sound level of the Single Branch Selector Boxes BSQ-T series could increase 3 dB(A) higher than maximum while the systems is
operating in the Low Ambient Cooling mode. It is recommended to locate units away from zones sensitive to sound levels.
• Allowable height difference between outdoor and indoor units (when outdoor unit is below) is limited to 130 ft. (40 m).
(Normal limit is 195 ft. (60 m).)
* Contact your local Daikin representative for wind cover specification requirements and part numbers.
COOLING
110
100
90
80
70
60
50
40
30
20
10
0
-10
60 70 80
Indoor temperature (˚FWB)
66
EDUS371704C-D