Installation & Operating Instructions
BAPI-Stat 4 “X-Combo”, Room %RH and Temp. Sensor
BA/BS4XC
Building Automation Products, Inc., 750 North Royal Avenue, Gays Mills, WI 54631 USA
Tel:+1-608-735-4800 • Fax+1-608-735-4804 • E-mail:[email protected] • Web:www.bapihvac.com
7 of 8
rev. 10/28/16
27939_ins_BS4XC
Possible Solutions
- Check for proper wire terminations and determine that the humidity input is set up correctly in the
controller and in the building automation software.
- Check the wiring between the sensor and controller (as described above).
- Check the sensor humidity output against a reference. Measure
the humidity at the sensor’s location using an accurate standard.
Disconnect the humidity channel wires and measure the humidity
signal with a multi-meter and compare to the reference, using the
equations at right for the reference. If the output and reference differ
by more than 5%, call BAPI
technical support.
- Determine if the sensor
is exposed to an external
source different from the room
environment (conduit draft).
Plug the conduit or fill the
handy box as necessary. DO
NOT use silicon caulk.
Voltage Humidity Equation
RH = RH
Low
+ (V-V
Low)
x (RH
Span
)
V
Span
RH
= %RH at sensor
RH
Low
= Low %RH of Span
RH
High
= High %RH of Span
RH
Span
= RH
High
- RH
Low
V
Low
= Low transmitter voltage
usually=(0, 1 or 2v)
V
High
= High transmitter voltage
usually=(5 or 10v)
V
Span
= V
High
- V
Low
V
= Signal reading in volts
4-20mA Humidity Equation
RH = RH
Low
+ (A -4) x (RH
Span
)
16
RH
= %RH at sensor
RH
Low
= Low %RH of Span
RH
High
= High %RH of Span
RH
Span
= RH
High
- RH
Low
A
= Signal reading in mA
Problems:
Humidity
Reading is
Incorrect
Possible Solutions
- Check for proper wire terminations and determine that the temperature input is set up correctly in the
controller and in the building automation software.
- Check the wiring between the sensor and controller. Label the terminals at the sensor end and the
controller end. Disconnect the interconnecting wires from the controller and the sensor. With the
wires disconnected, measure the resistance from wire-to-wire with a multimeter. The meter should
read greater than 10 Meg-ohms, open or OL depending on the meter. Short the interconnecting
wires together at one end. Go to the other end and measure the resistance from wire-to-wire with a
multimeter. The meter should read less than 10 ohms (22 gauge or larger, 250 feet or less). If either
test fails, replace the wire.
- Check the sensor temperature output against a reference. Measure the temperature at the sensor’s
location using an accurate temperature standard. Disconnect the temperature channel wires and
measure the temperature signal with a multi-meter and compare to the reference temperature. For
resistive output units, use the “Sensor Specs” tables in the “Resource Library” section of the BAPI
website (www.bapihvac.com) for the reference. For voltage or current output units, use the equations
below for the reference. If the output and reference differ by more than 5%, call BAPI technical support.
- Make sure that the Test and Balance switch is in the correct position.
- Make sure that the temperature sensor element leads are not touching one another.
- Determine if the sensor is exposed to an external source different from the room environment (conduit
draft). Plug the conduit or fill the handy box as necessary. DO NOT use silicon caulk.
- Make sure that the setpoint output is correct. Remove the
setpoint output wire (Channel 1, 2 or 3. See product label for
configuration.) and check
the output for the correct
resistance, current or
voltage output. Call BAPI
technical support if the
value doesn’t match the
label.
Diagnostics - Temperature Output
Voltage Temperature Equation
T = T
Low
+ (V-V
Low)
x (T
Span
)
V
Span
T
= Temperature at sensor
T
Low
= Low temperature of span
T
High
= High temperature of span
T
Span
= T
High
- T
Low
V
Low
= Low transmitter voltage
usually=(0, 1 or 2v)
V
High
= High transmitter voltage
usually=(5 or 10v)
V
Span
= V
High
- V
Low
V
= Signal reading in volts
4-20mA Temperature Equation
T = T
Low
+ (A -4) x (T
Span
)
16
T
= Temperature at sensor
T
Low
= Low temperature of span
T
High
= High temperature of span
T
Span
= T
High
- T
Low
A
= Signal reading in mA
Problems:
Temperature
Reading is
Incorrect
Setpoint
reading is
incorrect
Diagnostics - Humidity Output
