York YCAV0569, Installation Operation & Maintenance

Page: 157 / 278

157
JOHNSON CONTROLS
FORM 201.21-NM2 (616)
CONDENSOR FAN CONTROL
FAN
12
SYS
#2
SYS
#1
FAN
10
FAN
8
FAN
6
FAN
4
FAN
2
FAN
11
FAN
9
FAN
7
FAN
5
FAN
3
FAN
1
VSD/
CONTROL
PANEL
11 FAN UNITS - OMIT FAN 12
10 FAN UNITS - OMIT FANS 11 & 12
9 FAN UNITS - OMIT FANS 10,11 & 12
8 FAN UNITS - OMIT FANS 9,10,11 & 12
FAN LOCATIONS
FAN BAFFLES FAN BAFFLES FAN BAFFLES
LD10632
Condenser Fan control on each system is based on dis-
charge pressure. There are up to five possible stages of
fan control utilizing 3 outputs per system. Depending
upon the chiller model, there will be 4,5, or 6 fans per
system. The fan nearest the discharge liquid header
will always be the first fan on a system to start. As fan
stages increment or decrement, a single fan or pair of
fans contained within a pair of fan baffles will be turned
on or off. The diagram above shows the location of
the fan baffles. These baffles will not change location
regardless of the number of fans on a chiller.
The fan control algorithm in the Chiller Control Board
software will not skip steps as fan stages are staged up
and down. The delay between turning on or off fan
stages as discharge pressure rises and falls is 5 seconds.
The controller increments or decrements the fan stage
by one stage based on discharge pressure and fan delay
time.
TABLE 11 shows the fan staging and the outputs for each
fan stage on 4, 5, and 6 fan systems. The microproces-
sor fan outputs and the fan contactors will be the same
regardless of the number of fans. The fan wiring will
change to permit operation of 4,5, or 6 fans.
TABLE 11 - FAN STAGES AND CORRESPONDING OUTPUTS
4 FANS 5 FANS 6 FANS OUTPUT CONTACTORS
Stage 1
(1 Fan ON)
Sys 1 Fan 1
Sys 2 Fan 2
Stage 1
(1 Fan ON)
Sys 1 Fan 1
Sys 2 Fan 2
Stage 2
(2 Fans ON)
Sys 1 Fans 1 & 11
Sys 2 Fans 2 & 12)
1 Sys 1: 4CR
Sys 2: 7CR
Stage 2
(2 Fans ON)
Sys 1 Fans 3 & 5
Sys 2 Fans 4 & 6
Stage 2
(2 Fans ON)
Sys 1 Fans 3 & 5
Sys 2 Fans 4 & 6
-
2 Sys 1: 5CR
Sys 2: 8CR
Stage 3
(3 Fans ON)
Sys 1 Fans 1, 3, & 5
Sys 2 Fans 2, 4 & 6
Stage 3
(3 Fans ON)
Sys 1 Fans 1, 3, & 5
Sys 2 Fans 2, 4, & 6
Stage 4
(4 Fans ON)
Sys 1 Fans 1, 3, 5, & 11
Sys 2 Fans 2, 4, 6, & 12
1 and 2 Sys 1: 4CR & 5CR
Sys 2: 7CR & 8CR
-
Stage 4
(4 Fans ON)
Sys 1 Fans 3, 5, 7, & 9
Sys 2 Fans 4, 6, 8, & 10
-
2 and 3 Sys 1: 5CR & 6CR
Sys 2: 8CR & 9CR
Stage 4
(4 Fans ON)
Sys 1 Fans 1, 3, 5, & 7
Sys 2 Fans 2, 4, 6, & 8
Stage 5
(5 Fans ON)
Sys 1 Fans 1, 3, 5, 7, & 9
Sys 2 Fans 2, 4, 6, 8, & 10
Stage 6
(6 Fans ON)
Sys 1 Fans 1, 3, 5, 7, 9, & 11
Sys 2 Fans 2, 4, 6, 8, 10, & 12
1, 2, and 3 Sys 1: 4CR, 5CR, & 6CR
Sys 2: 7CR, 8CR, & 9CR
7