Vertiv Liebert PDX - Loop Temperatures and Mechanical Requirements

8
Liebert
®
PDX, EconoPhase Version - UM - 265133 - 29.08.2019
NOTE
At startup and at switchover from compressor operation to pump
operation, more time is allowed to bring the temperature under con-
trol, but the temperature will never be allowed to go outside the
cooling proportional band.
• The pump di󰀨erential pressure is below 34 kPa for 30 minutes.
• The refrigerant temperature leaving the pump is below -1.1°C
for 60 minutes.
• The pump does not establish ow at a pump startup attempt.
• Power is lost at the Liebert
®
EconoPhase unit.
1.8.5 Loop Temperatures
The Liebert
®
EconoPhase page on the Liebert
®
iCOM
®
display
shows Dis Ref Temp (pump outlet temperature) and Suct Ref Temp
(evaporator outlet temperature).
While the outdoor loop temperature could be close to the same
on both circuits, the indoor loop temperatures (in most cases) and
pressures in Circuit 1 will be higher than in Circuit 2 because of
the staged cooling evaporator design in the Liebert
®
DA125. The
Suct Ref Temp will be a function of load, return air temperature and
pump speed.
Table 2 shows some representative loop temperatures for
EconoPhase at the outdoor rating condition, 1.6°C, for several
heat load conditions and two return air conditions. System pressure
drop for a given application will a󰀨ect these temperatures because
of its impact on ow rates for a given pump speed.
NOTE
The data in Table 2 is from a system tested in controlled conditions
and is for reference only.
Tab. 2 - Representative Liebert
®
EconoPhase loop temperatures at 1.6°C outdoor temperature
Load,
%
Outdoor
Temp.
°C
RA
Temp.
°C
Circuit 1 Circuit 2 Circuit 1 Circuit 2 Circuit 1 Circuit 2 Circuit 1 Circuit 2 Circuit 1 Circuit 2
Pump Speed, %
Dis Ref
Temp. °C
Suct Ref
Temp °C
Suction SH
°C
Evap Saturation
Temp °C
100 1.6 29.4 100 60 1.11 4.4 27.7 20 -5.6 -5.2 15.5 7.4
75 1.6 29.4 100 46 1.11 2.7 25.5 20.5 -7.6 -2.2 15.5 4.7
50 1.6 29.4 64 45 7.7 2.7 28.8 23.8 0.4 2 10.7 4.2
25 1.6 29.4 54 O󰀨 5 NA 28.8 NA 3.7 NA 7.5 NA
100 1.6 23.8 100 55 10 2.7 14.4 16.1 -16.4 -7.2 13 5.4
75 1.6 23.8 100 45 10.5 3.3 13.8 17.7 -16.9 -5 13.3 4.7
50 1.6 23.8 69 O󰀨 7.7 NA 22.7 NA -6 NA 11.2 NA
25 1.6 23.8 54 O󰀨 5 NA 23.3 NA -1.5 NA 7.3 NA
1.8.6 Mechanical Considerations
The Liebert
®
EconoPhase pump is located at the condenser
(receiver) outlet and always needs liquid at its inlet for proper
function. The lines between the receiver and the Liebert
®
EconoPhase unit must be sloped down toward the Liebert
®
EconoPhase unit without any traps and with minimal bends. Traps
in those lines will prevent the pump from establishing and from
maintaining ow.
It is equally important to pump operation that the receiver be
su󰀩ciently above the Liebert
®
EconoPhase unit; refer to Figure
13 for the proper height di󰀨erence.
It is also important that the circuits do not get crossed between the
indoor unit, the condenser and the Liebert
®
EconoPhase unit. If
they get crossed, the system will not operate correctly, either in DX
mode or in Liebert
®
EconoPhase operation.