York YCAS0295EB, Installation Operation & Maintenance

Page: 171 / 194

171 YORK INTERNATIONAL
FORM 201.19-NM7 (804)
8
The chiller is equipped with 8 or 10 condenser fans, with
4 or 5 fans per system as given below. Fan control is
via Outside Ambient Temperature (OAT) and Discharge
Pressure (DP). There are 4 or 5 stages of fan control,
utilizing 3 outputs per system. The fan stages will work
according to Table 3 and 4 depending on the number of
fans per system. There will be a variable delay between
all fan stages. The delay between turning on fan stages
is based on the ambient temperature. The time is ramped
from 30 seconds at 10ºF (-12.2ºC) to 5 seconds at 60ºF
(15.6ºC) (time delay = (35 - (oat/2)).
Condenser fan ON conditions are governed solely by the
Discharge Pressure (DP). When the DP rises above 230
PSIG, fan stage 1 is activated. From here, subsequent
fan stages are activated as the DP rises in increments of
10 - 20 PSIG. The system will remain at the highest fan
stage reached unless the OFF conditions are satisfi ed.
Condenser fan OFF conditions are governed by both
the DP and OAT. Fan staging will be decreased from
the highest fan stage reached if both the DP and OAT
requirements are met. For example, if a system is at
a fan stage of 4, and the DP falls under 205 PSIG and
the OAT drops below 75ºF (24ºC), the fan stage will be
reduced to 3.
FIG. 54 –
CONDENSER FAN LAYOUT FOR DXST 2
COMPRESSOR UNITS
LD03676
Tables 3 and 4 describe fan operation and contactor data
for the fans involved in each fan stage. SYS 1 uses relay
board #1. SYS 2 uses relay board #2.
YCAS0295 - YCAS0575 models have 4 condenser
fans/system:
8.8 CONDENSER FAN CONTROL
0605EB