H7625B; H7635B,C; H7655B
Duct-Mount and Outdoor-Mount
Humidity/Temperature Sensors
INSTALLATION INSTRUCTIONS
APPLICATION
The H7625B, H7635B, H7655B Duct-Mount and H7635C
Outdoor-Mount Humidity/Temperature Sensors are
universal Relative Humidity transmitters that can be
powered with either a +18 to 36 Vdc or 24 Vac supply.
The sensors use a half-wave bridge rectifier to convert
AC power to a usable DC voltage. The device also
includes a 20K ohm temperature sensor for optional use.
The humidity sensors are designed with a fieldselectable 4to20 mA, 0to5Vdc, or 0to10Vdc output
signal equivalent to 0 to 100% RH. All units are shipped
from the factory with a default setting to accept AC power
with three-wire, 0 to 10 Vdc loop-powered output.
INSTALLATION
When Installing this Product...
1. Read these instructions carefully. Failure to follow
them could damage the product or cause a
hazardous condition.
2. Check ratings given in instructions and on the
product to ensure the product is suitable for your
application.
3. Installer must be a trained, experienced service
technician.
4. After installation is complete, check out product
operation as provided in these instructions.
CAUTION
Electrical Shock or Equipment Damage
Hazard.
Can shock individuals or short equipment
circuitry.
Disconnect power supply before installation.
Mounting
The method of mounting depends on the particular
sensor application. The following procedures include
outdoor and duct applications. Also refer to the
instructions for the electronic control.
Duct Mounting
The H7625B, H7635B and H7655B can be mounted in a
duct to sense humidity and temperature.
IMPORTANT
Select a location to expose sensor to average
duct humidity and temperature. Avoid locations
where stratification can cause sensing errors.
NOTES:
— H7635C is weatherproof for outdoor use.
Knockouts allow 1/2 in. conduit connection.
— To avoid damaging board during installation,
the cover can be detached completely:
1.Carefully remove wire plug from board.
1. Cut a hole in the duct just large enough to accept
2. Open case by rotating the cover counterclockwise.
3. Mount standard 1/2 in. conduit to the case.
4. Use case to mark mounting screw pilot hole
5. Drill the pilot holes and fasten the sensor to the
6. Wire the sensor. See Wiring section.
7. Reattach the wire plug and cover being careful not
2.Set the cover aside.
the sensing element.
locations.
duct.
NOTE: The two free wires are thermistor wiring
connections. When connecting these, use
two wire nuts.
to pinch wires between the cover and case.
CAUTION
Equipment Damage Hazard.
Improper wiring can damage the sensor
beyond repair.
Follow the wiring instructions carefully.
63-2579—3
H7625B; H7635B,C; H7655B DUCT-MOUNT AND OUTDOOR-MOUNT HUMIDITY/TEMPERATURE SENSORS
Outdoor Mounting
The H7635C senses outdoor air humidity and
temperature. Mount this control where it can sense
average outdoor air humidity and temperature. Normally,
the north side of a building provides a suitable location.
NOTES:
— H7635C is weatherproof for outdoor use.
Knockouts allow 1/2 in. conduit connection.
— To avoid damaging board during installation,
the cover can be detached completely:
1.Carefully remove wire plug from board.
2.Set the cover aside.
1. Open case by rotating the cover counterclockwise.
NOTE: Orient case so the element points down.
2. Mount standard 1/2 in. conduit to the case.
3. Use case to mark mounting screw pilot hole
locations.
4. Drill pilot holes.
5. Fasten the case to the wall.
6. Wire the sensor. See Wiring section.
NOTE: The two free wires are thermistor wiring
connections. When connecting these, use
two wire nuts.
7. Reattach the wire plug and cover being careful not
to pinch wires between the cover and case.
Output Settings (Table 1)
The board has three switch blocks:
— A six DIP switch block.
— A four DIP switch block.
— A white gang switch on a blue block.
1. Adjust the 4-switch block according to Table 1.
NOTE: The 6-switch block normally requires no
adjustment. (See the Appendix.)
2. Set the gang switch (white switch in blue block) to
correspond with the output (mA or Vdc).
NOTE: See Fig. 1 for DIP switch locations.
Table 1. Controller Compatibility
and Output Settings.
Required
4-Switch Block
Controller
W7750, W7760,
W7761
W7750B,C
W7760C,
W7753, W7760
T7350, XL50,
XL100,
XL500 XF
Modules, XFL
Sensor
Output
Setting
4-20 mA — On — — 4-20 mA C7600C
0-10 Vdc
(default)
0-10 Vdc
(default)
Settings
On — — On Vout H7621/31
On — — On Vout n/a
Non-Honeywell 0-5 Vdc On — On — Vout n/a
Blue and
White
Output
Switch
ONSPEC™
L
Setting4321
NORMAL OPERATION
OFF
ON
Fig. 1. DIP switch locations and settings.
63-2579—3 2
OFF
ON
OFF
ON
OFF
ON
0-10 VDC
4-20 MA
0-5 VDC
M22705
H7625B; H7635B,C; H7655B DUCT-MOUNT AND OUTDOOR-MOUNT HUMIDITY/TEMPERATURE SENSORS
WIRING
For voltage output, shielded cable (16-22 AWG) should
be used.
For current output, either shielded cable or twisted pair
(16-22 AWG) can be used.
NOTE: When using shielded cable, ground the shield
only at the controller end (see Fig. 2). Grounding
both ends can cause a ground loop.
The 20K ohm NTC temperature output is accessed
through the separate blue and green wires (located inside
the enclosure).
OUTDOOR
5
Gnd Vin
(Vac)
AIR
SENSOR
123456789
T3
OSOS ASAS
M
MHC HP
MOTION
SENSOR
T7770 REMOTE SENSOR
T7350
SUBBASE
T5 T6 T7 T4
HS
Vo
(0-10 Vdc)
HUMIDITY SENSOR
L2
2
1
L1
(HOT)
POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED.
1
ENSURE TRANSFORMER IS SIZED TO HANDLE THE LOAD.
2
3
HEAT/COOL SYSTEMS WITH ONE TRANSFORMER REQUIRE THE FACTORY-INSTALLED JUMPER.
4
USE ECONOMIZER INSTRUCTIONS FOR INSTALLATION DIRECTIONS.
5
HC AND HP PROVIDE 24 VAC TO THE HUMIDITY SENSOR.
Fig. 3. Humidity sensor (0-10 Vdc output) wiring with T7350
(use with RH/Temperature combination T7350 units only).
mA OUTPUT
TRANSDUCER
ONLY
18 TO 36 Vdc
POWER SUPPLY
Vin +
Io –
CONTROLLER, METER
OR RECORDER
INPUT SIGNAL
+
COMMON
–
GROUND
Fig. 2. Typical wiring diagram for transducer with two-
wire mA output and external DC power supply.
HEAT
RELAY 2
DISCHARGE
AIR
SENSOR
COMPRESSOR
CONTACTOR 4
W3/Y4 Y3 W2
RCX
AUXRH
3
4
ECONOMIZER
W1 G
HEAT
RELAY 1
COMPRESSOR
CONTACTOR 1
COMPRESSOR
CONTACTOR 2
Y2
Y1
FAN
RELAY
COMPRESSOR
CONTACTOR 3
M22529
M22528
3 63-2579—3
H7625B; H7635B,C; H7655B DUCT-MOUNT AND OUTDOOR-MOUNT HUMIDITY/TEMPERATURE SENSORS
P7640
PWR
+
COM
–
O
OUT
W7760A
OUT1OUT2OUT3OUT4OUT5OUT6OUT7OUT8DI1DI2DI3DI4GND GND
P7640
PWR
+
COM
–
O
OUT
12345 6789101112 14 1615
E
GND
AI1AI
AI3AI
AI
2
GND
17 18 19 20 21 22 23 24 25 26 27 28 29
(HOT)
1
POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED.
1
TEMPERATURE SIGNAL CONNECTIONS ARE NOT POLARITY SENSITIVE.
2
Fig. 4. Typical wiring diagram for 5-wire temperature/humidity sensor with Vdc output
(used with the XL15A controller).
Vin (Vac)
+
Gnd
–
Vo (0-10 Vdc)
O
4
GND
L1
L2
AI
H76XX
+
2
–
13
AI5AI6AI7AI
AI
GND
24
24
24
VAC
VAC
VAC24VAC24VAC24VAC24VAC
COM
COM
ANALOG
AI
OUT
8
GND
AO1AO
31 32 33 34 35 36 37 38 39 40 41 42 43
OUT
COM
AO
GND
2
21
VDC
OUT
GND E-BUS E-BUS
44
M18302B
63-2579—3 4
H7625B; H7635B,C; H7655B DUCT-MOUNT AND OUTDOOR-MOUNT HUMIDITY/TEMPERATURE SENSORS
CHECKOUT
CAUTION
Converting Output Signal to Percent RH
Equipment Damage Hazard.
Can short electric circuitry.
• Never connect 120 Vac to the transducer.
• Connect only DC voltage to a transducer
intended for DC supply.
NOTE: Use laboratory quality meters and gauges for
applications requiring a high degree of accuracy.
1. Verify the transducer is mounted in the correct position.
2. Verify appropriate input signal and voltage supply.
3. Verify appropriate configuration range.
Table 2. Troubleshooting.
Problem Items to Check
No reading • Verify correct supply voltage at the power terminal blocks.
Erratic readings • Verify all wires are terminated properly.
• Verify correct wiring configuration and DIP switch settings.
• Verify that terminal screws are connected tightly with all wires firmly in place.
• Ensure that there is no condensation on the board.
• Verify clean input power. In areas of high RF interference or noise, shielded cable can be
necessary to stabilize signal.
4 to 20mA Signal
signal [in mA] 4–〈〉
------------------------------------------------- p er ce n t R H=
0.16
Example: 12 mA output signal
(12 - 4)/ 0.16 = 50% RH
0 to 10 Vdc Signal
Example: 8 VDC transmitter signal output
8 Vdc/0.10 = 80% RH
5 63-2579—3
H7625B; H7635B,C; H7655B DUCT-MOUNT AND OUTDOOR-MOUNT HUMIDITY/TEMPERATURE SENSORS
APPENDIX
RH Test and Configuration DIP Switch Settings (Table 3)
IMPORTANT
• Only adjust these switches for troubleshooting or
recalibrating the sensor. (Adjustment is not
normally necessary.)
• For normal operation, always keep DIP switch 3
in the ON position. When DIP switch 3 is off, the
RH transmitter cannot read the sensor. This
inability-to-read forces the output to never
change.
Table 3. Test/Calibration Settings (Six-Switch Block).
Setting 654321
Normal Operation (Default) — — — On — —
0% RH Output On—————
50% RH Output —On————
100% RH Output — — On — — —
Increment RH Output — — — — On —
Decrement RH Output —————On
Reset to Original Calibration — — — — On On
0% RH Output (for Testing Only)
Transmitter always outputs a signal of 4 mA or 0 Vdc. The
sensor does not affect the transmitter output.
50% RH Output (for Testing Only)
Transmitter always outputs a signal of 12 mA, 2.5 VDC, or
5 VDC. The sensor does not affect transmitter output.
100% RH Output
Transmitter always outputs a signal of 20 mA, 5 VDC, or
10 VDC. The sensor does not affect the transmitter
output. Sensor doesn’t affect the transmitter output.
Normal Operating Condition
DIP switch 3 must be set in the On position for normal
operation. All other DIP switches must be set Off.
63-2579—3 6
H7625B; H7635B,C; H7655B DUCT-MOUNT AND OUTDOOR-MOUNT HUMIDITY/TEMPERATURE SENSORS
CALIBRATION
All transducers are factory calibrated to meet/exceed published
specifications. Field adjustment should not be necessary.
IMPORTANT
• Do not verify comparative RH with a sling
psychrometer. Too many variables exist which
induce errors into this process.
• Recalibration must be done in a controlled
environment. Relative humidity must be held
stable while making any adjustment.
• Verify the device output directly with calibrated
instrumentation and verify RH with calibrated
instrumentation. Never use a controller output.
• With correct power applied, and only a meter
connected to the transducer output, ensure that
the output is proportional to the true RH.
Using Increment/Decrement Switches
Increment RH Output
This DIP switch allows you to calibrate the sensor through
the software. The switch must be toggled from the Off to
the On position and then returned to the Off position for
an increase of 0.5% RH. This means that if your humidity
has drifted 1% lower over a certain time period, you can
toggle the Increment RH Output switch (2 times) in order
to slide the whole curve upward 1%.
Decrement RH Output
This DIP switch allows calibration in the same way as the
Increment RH. The difference is that each toggle results
in a decrease of 0.5% RH.
Using Calibration Trim Potentiometers
IMPORTANT
• Due to sensitive nature of humidity calibration,
adjusting trimmer potentiometers is not highly
recommended.
• Calibrate only in a stable humidity/temperature
chamber of laboratory grade.
Single Point Calibration
IMPORTANT
Use only one of the following two options.
OPTION 1
1. Select a controlled humidity environment between
10 and 40 percent RH. Be sure humidity is stable.
2. Adjust zero trimmer (z).
OPTION 2
1. Select a controlled humidity environment between
40 and 70 percent RH. Be sure humidity is stable.
2. Adjust span trimmer (s).
Two Point Calibration
1. Select a controlled humidity environment between
10 and 40 percent RH. Be sure humidity is stable.
2. Adjust zero trimmer (z).
3. Select a controlled humidity environment between
70 and 75 percent RH. Be sure humidity is stable.
4. Adjust span trimmer (s).
7 63-2579—3
LonSpec™ is a trademark of Echelon® Corporation.
Automation and Control Solutions
Honeywell International Inc. Honeywell Limited-Honeywell Limitée
1985 Douglas Drive North 35 Dynamic Drive
Golden Valley, MN 55422 Scarborough, Ontario M1V 4Z9
customer.honeywell.com
® U.S. Registered Trademark
© 2005 Honeywell International Inc.
63-2579—3 B.B. Rev. 01-05
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