Bacnet/Ip Module; Bacnet Ms/Tp Module; Lonmark Module; Troubleshooting Static Pressure Transducers - McQuay MicroTech II Installation And Maintenance Manual

Table 25: MicroTech II temperature sensor—
temperature vs. resistance chart
Temperature °F (°C)
-40 (-40)
-31 (-35)
-22 (-30)
-13 (-25)
-4 (-20)
5 (-15)
14 (-10)
23 (-5)
32 (0)
41 (5)
50 (10)
59 (15)
68 (20)
77 (25)
86 (30)
95 (35)
104 (40)
113 (45)
122 (50)
131(55)
140 (60)
149 (65)
158 (70)
167 (75)
176 (80)
185 (85)
194 (90)
203 (95)
212 (100)
221(105)
230(110)
239 (115)
248 (120)

BACnet/IP Module

For a detailed description and troubleshooting information
regarding the BACnet/IP communications module, refer to
installation and maintenance bulletin IM 703, MicroTech II
BACnet/IP Communications Module. For details regarding
BACnet protocol data, refer to engineering data document,
ED 15 061, MicroTech II Protocol Information Data for
Vertical Self-Contained Units.
42
Resistance in Ohms
613
640
668
697
727
758
789
822
855
889
924
960
997
1035
1074
1113
1153
1195
1237
1279
1323
1368
1413
1459
1506
1554
1602
1652
1702
1753
1804
1856
1908

BACnet MS/TP Module

For a detailed description and troubleshooting information
regarding the BACnet MS/TP communications module,
refer to installation and maintenance bulletin IM 704,
MicroTech II BACnet MS/TP Communications Module. For
details regarding BACnet protocol data, refer to engineering
data document, ED 15 061, MicroTech II Protocol
Information Data for Vertical Self-Contained Units.
L M Module
ON ARK
For a detailed description and troubleshooting information
regarding the LonMark communications module, refer to
installation and maintenance bulletin IM 702, MicroTech II
L W Communications Module. For details regarding
ON ORKS
L M protocol date, refer to engineering data
ON ARK
document, ED 14 061 MicroTech II Protocol Information
Data for Vertical Self-Contained Units.
Troubleshooting Static Pressure
Transducers
To troubleshoot a suspect sensor, use the procedure below:
1. If the duct static pressure always reads 0" WC on the
unit keypad/display and the discharge inlet vane
position of AFD speed is continuously ramping to
100%, check the following:
a. If the unit has two duct static pressure sensors
(SPS1 and SPS2), verify that they both function
properly following steps 2 through 5 below. Also
check for faulty wiring connections at analog inputs
MCB-AI13 and MCB-AI14. The controller
displays and controls to the lower of the two
readings. If one is defective and inputs 0 volts to the
controller, the static pressure reading on the
keypad/display reads 0 and the controller attempts
to increase the 0 value to setpoint by ramping up the
discharge inlet vanes or AFD.
b. If a second sensor (SPS2) is not installed or the
pressure tubing to it is not connected, make sure the
2nd P Sensor= parameter in the Unit Configuration
menu of the keypad/display is set to "None" so that
the controller ignores the second static pressure
analog input MCB-AI14.
c. If a second sensor (SPS2) is installed, but it is a
building space rather than a duct static pressure
sensor, make sure the 2nd P Sensor= parameter in
the Unit Configuration menu of the keypad/display
is set to "Bldg."
2. Verify the 24 VAC power supply to the sensor.
a. If the sensor is SPS1 or SPS2 (duct static), verify
that there is 24 VAC between the suspect transducer
"+" and "-" terminals.
b. If the sensor is SPS2 (building static) verify that
there is 24 VAC between the "IN" and "CM2"
terminals on the SPS2 terminal block.
c. If 24 VAC supply reads low and/or the MCB is
malfunctioning, the sensor may be drawing too
McQuay IM 710-1