Quantech QCC2015CEE, Installation, Operation And Maintenance Manual, Page: 138 / 172

QUANTECH
138
Form QCC2-NM1
Issue Date: 5/20/2021
SECTION 8 – UNIT OPERATION
Condenser fan control - QCC2015C – QCC2070C
Table 20 - QCC2015C – QCC2070C Low Ambient Condenser Fan Control –
Discharge Pressure Control
FAN
STAGE
ON OFF
CONTACTOR
I/O BOARD
OUTPUT
FAN #
SYS 1 SYS 2 SYS 1 SYS 2 SYS 1 SYS 2
1
1 FAN
REV
DP > Fan Ctrl On
Press
DP < Fan Ctrl On Press
– Diff. Press.
7M 10M TB7-8 TB10-8 1 REV 2 REV
2
1 FAN
FWD
DP > Fan Ctrl On
Press
+ 20 psig
(1.38 Bars)
DP < Fan Ctrl On Press.) –
[Diff Press. + 20 psig
(1.38 Bars)]
8M 11M TB7-9 TB10-9
3
FWD
4
FWD
3
2 FANS
FWD
DP > Fan Ctrl On
Press
+ 40 psig
(2.76 Bars)
DP < Fan Ctrl On Press.) –
[Diff Press. + 40 psig
(2.76 Bars)]
8M & 9M 11M &
12M
TB7-9
&
TB7-10
TB10-9
& TB10-10
1 & 3
FWD
2 & 4
FWD
Table 21 - QCC2015C – QCC2030C Low Ambient Condenser Fan Control –
Discharge Pressure Control
FAN STAGE ON OFF CONTACTOR
I/O BOARD
OUTPUT
FAN #
Stage 1
"OAT > 25° F or
DP > ctrl_press"
"OAT < 20° F and
DP < ctrl_press - diff_press"
7M TB7-8 1 REV
Stage 2
"OAT > 45° F or
DP > ctrl 20
psig"
"OAT < 40° F and
DP < ctrl_press - diff 20
psig"
8M TB7-9 3 FWD
When Low Ambient Control of the fans is
selected, fan control will be by discharge
pressure only.