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8.5
4 COMPRESSOR
CONDENSER FAN CONTROL
The chiller is equipped with 14 or 18 condenser fans,
with 3, 4 or 5 fans per system as given below. Fan con-
trol is via Outside Ambient Temperature (OAT) and Dis-
charge Pressure (DP). There are six stages of fan con-
trol utilizing 3 outputs per system. The fan stages will
work according to Table 2 or Table 3 depending on the
number of fans/system. There will be a minimum 5 sec-
ond delay between all fan stages.
Condenser fan ON conditions are governed solely by
the Discharge Pressure (DP). When the DP rises above
220 PSIG, fan stage 1 is activated. From here, subse-
quent fan stages are activated as the DP rises in incre-
ments of 15 PSIG, except stage 6, which is activated
when the DP rises over 290 PSIG. The system will re-
FIG. 76 – CONDENSER FAN CONTROL LAYOUT FOR DXST COMPRESSORS UNITS
TABLE 6 – CONDENSER FAN CONTROL AND FAN CONTACTOR DATA FOR DXST UNITS
WITH 4 FANS/SYSTEM
Fan
Fans
Stage
1
1
S
2
3
Y
3
5, 7
S
4
1, 5, 7
5
3, 5, 7
1
6
1, 3, 5, 7
1
2
S
2
4
Y
3
6, 8
S
4
2, 6, 8
5
4, 6, 8
2
6
2, 4, 6, 8
Fan
Fans
Stage
1
13
S
2
15
Y
3
17, 19
S
4
13, 17, 19
5
15, 17, 19
3
6
13, 15, 17, 19
1
14
S
2
16
Y
3
18, 20
S
4
14, 18, 20
5
16, 18, 20
4
6
14, 16, 18, 20
* Newer versions of EPROMs will have ON and OFF pressures 15 PSIG below the published values shown above.
YORK INTERNATIONAL
ON *
OFF *
Conditions
Conditions
DP
DP & OAT
>220 PSIG
<150 PSIG & <60°F
>235 PSIG
<165 PSIG & <65°F
>250 PSIG
<180 PSIG & <70°F
>265 PSIG
<195 PSIG & <75°F
>280 PSIG
<210 PSIG & <80°F
>290 PSIG
<220 PSIG & <85°F
>220 PSIG
<150 PSIG & <60°F
>235 PSIG
<165 PSIG & <65°F
>250 PSIG
<180 PSIG & <70°F
>265 PSIG
<195 PSIG & <75°F
>280 PSIG
<210 PSIG & <80°F
>290 PSIG
<220 PSIG & <85°F
ON *
OFF *
Conditions
Conditions
DP
DP & OAT
>220 PSIG
<150 PSIG & <60°F
>235 PSIG
<165 PSIG & <65°F
>250 PSIG
<180 PSIG & <70°F
>265 PSIG
<195 PSIG & <75°F
>280 PSIG
<210 PSIG & <80°F
>290 PSIG
<220 PSIG & <85°F
>220 PSIG
<150 PSIG & <60°F
>235 PSIG
<165 PSIG & <65°F
>250 PSIG
<180 PSIG & <70°F
>265 PSIG
<195 PSIG & <75°F
>280 PSIG
<210 PSIG & <80°F
>290 PSIG
<220 PSIG & <85°F
main at the highest fan stage reached unless the OFF
conditions given in the next paragraph are satisfied.
Condenser fan OFF conditions are governed by both
the DP and OAT. Fan staging will be decreased from
the highest stage reached if both the DP and OAT re-
quirements are met. For example, if a system is at a fan
stage of 4, and the DP falls under 195 PSIG and the
OAT drops below 75°F, the fan stage will be reduced to
3. The ON/OFF conditions are provided in the next two
tables.
The tables below also indicate fan contactors, wire num-
bers, and Relay Output Board or I/O Expansion Board
Output numbers relating to fans energized. SYS 1 fan
contactors are controlled by Relay Output Board # 1.
SYS 2 by Relay Output Board # 2. SYS 3 and 4 are
controlled by I/O Expansion Board #2.
Fan
Contactor
9M
10M
11M, 12M
9M, 11M, 12M
10M, 11M, 12M
9M, 10M, 11M, 12M
15M
16M
17M, 18M
15M, 17M, 18M
16M, 17M, 18M
15M, 16M, 17M, 18M
Fan
Contactor
21M
22M
23M, 24M
21M, 23M, 24M
22M, 23M, 24M
21M, 22M, 23M, 24M
27M
28M
29M, 30M
27M, 29M, 30M
28M, 29M, 30M
27M, 28M, 29M, 30M
FORM 201.18-NM3
LD05023
Relay
Wire
Board
Number
Output
130
15
131
14
132
10
130, 132
10, 15
131, 132
10, 14
130, 131, 132
10, 14, 15
230
15
231
14
232
10
230, 232
10, 15
231, 232
10, 14
230, 231, 232
10, 14, 15
I/O Expansion Board
Wire
Output
Number
(TB3 SYS) (TB4 SYS)
330
8
331
9
332
10
330, 332
8, 10
331, 332
9, 10
330, 331, 332
8, 9, 10
430
8
431
9
432
10
430, 432
8, 10
431, 432
9, 10
430, 431, 432
8, 9, 10
183
8
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