Johnson Controls YORK OPTIVIEW YK Series Service Instructions Manual page 308

SECTION 35 - SOFTWARE ENHANCEMENTS
SI0034 - SOFTWARE ENHANCEMENTS EFFECTIVE AUGUST 2002 (CONT'D)
CHILLER MOD –
COMPRESSOR
Mod C, D, E –
G, H, J Compr
Mod E – P Compr
Mod F – G, H
Compr
Mod F – J Compr
Mod F – P, Q
Compr
* Not applicable to Mod C (and earlier) chillers.
FACTORY MOUNTED FLOW SENSORS
Style F (and later) chillers are supplied with factory-
mounted flow sensors on the evaporator and condens-
er. These are electronic thermal-type sensors. The op-
erating principle of the sensor is thermal conductivity.
It uses the cooling effect of a flowing liquid to sense
flow. The temperature of the heated sensor tip is sensed
by a thermistor located in the tip.
A second thermistor, located higher in the tip in a non-
heated area, is only affected by changes in liquid tem-
perature. The temperatures sensed by the thermistors
are compared. Flowing liquid carries heat away from
the heated sensor tip, lowering its temperature. The
lower temperature differential between the two therm-
istors indicates the liquid is flowing. A higher differ-
ential indicates no flow. Each device operates from a
24VAC power source and has a solid state relay output.
On each sensor, one side of the solid state relay output
(pin 2) is connected to the microboard +5VDC and the
other side (pin 4) is connected to a Microboard Analog
Input.
308
OIL
PROXIMITY
HEATER
SENSE
OUTPUT*
Probe TB1-34
Limit Switch TB1-64
Limit Switch TB1-64
Probe TB1-64
Limit Switch TB1-64
LEVEL
CONTROL
FLOW SWITCH
PERIOD
DEFAULT
3.5 sec Paddle Type
10.0 sec Paddle Type
Factory Mounted
3.5 sec
Thermal Type
Factory Mounted
3.5 sec
Thermal Type
Factory mounted
10.0 sec
Thermal Type
When flow is sensed, the solid state relay output is
turned on causing it to conduct current through the
7.5K ohm microboard load resistor to the +5VDC. This
applies more than +4VDC to the microboard input
(evaporator J7-14; condenser J7-16). When no flow
is sensed, the solid state relay output is turned off, re-
sulting in no conduction through the load resistor. This
applies less than 1VDC to the microboard input. To de-
termine the state of the solid state relay, first confirm
that +5VDC is present at pin 2 of the flow sensor. Then
connect a voltmeter from Microboard J7-14 (evapora-
tor) or J7-16 (condenser) to Microboard TP1 (ground).
The power source is connected to the sensor as follows:
From
Sensor pin 1
pin 3
The sensor outputs are connected to the microboard as
follows:
Evaporator:
From
Sensor pin 2
pin 4
Condenser:
From
Sensor pin 2
pin 4
FORM 160.54-M1
OIL-VARIABLE SPEED
PUMP PRESSURE SETPOINT
NOT ACHIEVED
THRESHOLD*
35 PSID
25 PSID
35 PSID
35 PSID
25 PSID
To
TB1-162 (24VAC)
TB6-5 (GND)
To
Microboard J7-1 (+5VDC)
J7-14 (input to Microboard )
To
Microboard J7-15 (+5VDC)
J7-16 (input to Microboard)
JOHNSON CONTROLS