ELECTRONIC HUMIDISTAT: H270
• ONE OR TWO STAGES
• HUMIDITY SUPPLY HIGH LIMIT
• OUTDOOR TEMPERATURE RESET
DESCRIPTION
The H270 series low voltage, microcomputer-based PI
(proportional and integral) humidistats are designed for
accurate humidification and/or dehumidification control
in commercial applications such as: hospitals, schools,
office buildings, retail stores, museums, computer
rooms, etc.
The H270 series is available with one or two outputs
for maximum flexibility. Outputs can be of the following
type: proportional, on/off, and pulse width modulation
(PWM). Two additional inputs are provided in order to
perform unique functions: humidity setpoint reset
based on outdoor air temperature and proportional
high limit override. The former function minimizes
condensation on window surfaces during cold outdoor
temperatures by automatically lowering the humidity
setpoint as the outdoor temperature drops. The latter
function improves accuracy and safety by throttling
back the humidifier control output if the humidity level
reaches unacceptably high levels.
There are many different types of mounting
configurations available. Sensing options include
remote duct and room as well as integral room and
duct. Setpoint adjustment can be either concealed or
exposed, adding even more versatility to the product.
Exposed models feature internally selectable minimum
and maximum setpoint knob stops.
In order to facilitate periodic recalibration, the H270
series contains a unique autocal key, which permits
instant recalibration (see dimension drawing on page 5
for location).
Each humidistat is computer calibrated and factory
programmed with default parameters. All control
parameters (such as proportional band, stage
differential, etc.) may be changed in the field with the
H263 programming tool without having to remove the
thermostat cover. The H263 also doubles as a
diagnostic tool and indicates the status of all the inputs
and outputs, and will reduce troubleshooting time by
quickly identifying the specific problem.
Fig.1 Wall mounted humidistat
Features Benefits
• Microcomputer-based design with PI algorithm ⇒
• One or two outputs ⇒
• On/off and/or proportional outputs ⇒
• Direct or reverse acting outputs ⇒
• Integrated and remote sensing ⇒
• Autocal button ⇒
• Concealed or exposed set point ⇒
• Ouput signal to digital indicating devices ⇒
• Optional H263 diagnostic tool with digital display ⇒
• Sensor failure protection ⇒
• Humidity setpoint reset based on outdoor temp. ⇒
• Proportional high limit override ⇒
• CE approved ⇒
Exceptional accuracy
Controls humidification and dehumidification equipment
Greater flexibility
Controls humidification and dehumidification equipment
Larger choice of mounting options
Permits instant recalibration
Can be used in a large variety of environments
Increases functionality of product
Simplifies troubleshooting
Prevent water dammage
Prevents window condensation in colder climates
Prevents costly damage due to over-humidification
Can be sold in European markets
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TABLE 1: ORDER CODE
WIRING
H270 - A-B - C-D - E-F G-H
A Output no. 1 ( controlled device )
1 ON/OFF (15 min. time based)
4 (PWM) 24 VAC
5 (PWM) 5 VDC
6 Analog 0-10 Volts DC
B Output no. 2 ( controlled device )
0 Not installed
1 ON/OFF (15 min. time based)
4 (PWM) 24 Volts AC
5 (PWM) 5 Volts DC
6 Analog 0-10 Volts DC
8 Signal transmitter (0-10 VDC)
♦
(1V= 10% , 9V-90%)
9 Signal transmitter (0-5 VDC)
♦
(0.5V= 10% ; 4.5 V=90%)
C Output no. 1 and 2 control mode
1Humidify
2 Dehumidify
3 Humidify ( no. 1 ) and dehumidify ( no. 2 )
4 Dehumidify ( no. 1 ) and humidify ( no. 2 )
D Main sensor location Sensor
0 Not installed None
1 Inside humidistat ( Local ) H50
2 Duct mount ( stat on duct ) H60
3 Duct mount ( stat on wall ) H71
4 Remote wall mount H80
E Setpoint adjustment
1 User adjustable
2 Blind cover
F Future option
0 Unused
G Duct humidity supply high limit
0 Without sensor
3 With H71 duct mounted humidity sensor
H Outdoor temperature reset input
0 Without sensor
1 With S71 duct mounted outdoor temp.
sensor
Example: H270 - 61 - 32 – 10 - 31
One “SCR” 0 to 10 volts humidify output and one relay
dehumidify output. Humidistat and sensor are duct mount.
Setpoint is user adjustable. A remote duct mounted high limit
is installed in the supply. An outdoor temperature sensor is
installed to reset the humidity setpoint.
♦ Resolution: 0.5 % for retransmit only
See sensor specications for dimensions of sensors
Note: the complete order code includes the sensor that will be
shipped with the humidistat.
2 ON/OFF OUTPUTS
Single transformer
+
+
BLACK
WHITE
RED
BLACK
WHITE
RED
RELAY
or 24 Vac VALVE
-
RELAY
or 24 Vac VALVE
-
HUMIDITY SENSOR
FOR CONTROL
HUMIDITY SENSOR
HIGH LIMIT
S71
TEMPERATURE SENSOR
24 Vac
INPUT
SIGNAL
RESET
+10 Vdc
1
2
3
4
5
6
7
8
9
10
24 Vac
OUTPUT #2
ON / OFF
OUTPUT #1
ON / OFF
COMMON
MAIN SENSOR
HIGH LIMIT
HUMIDITY
OUTDOOR
Fig.2: Wiring diagram with single transformer
Multiple transformers
24 Vac
+
+
BLACK
WHITE
RED
BLACK
WHITE
RED
RELAY
or 24 Vac VALVE
-
RELAY
or 24 Vac VALVE
-
HUMIDITY SENSOR
FOR CONTROL
HUMIDITY SENSOR
HIGH LIMIT
S71
TEMPERATURE SENSOR
24 Vac
INPUT
SIGNAL
RESET
+10 Vdc
1
2
3
4
5
6
7
8
9
10
24 Vac
24 Vac
OUTPUT #2
ON / OFF
OUTPUT #1
ON / OFF
COMMON
MAIN SENSOR
HIGH LIMIT
HUMIDITY
OUTDOOR
Fig.3: Wiring diagram with multiple transformers
Note: both of the above wiring diagrams show how to
wire output of type 1, 2, 3 and 4 (switched 24 vac).
For outputs of type 5 and 6 (vdc out) refer to wiring diagrams
3 and 4 on next page.
2
2 PROPORTIONNAL OUTPUT
1 PROPORTIONNAL AND 1 TRANSMITTER OUTPUT
OUTPUT # 2
0 to 5 Vdc
0 to 10 Vdc
TRANSMITTER
OUTPUT # 1
0 to 10 Vdc
COMMON
MAIN SENSOR
HIGH LIMIT
SENSOR
OUTDOOR
TEMP. SENSOR
+10 Vdc
Fig.5: Wiring diagram with one analog and one transmitter output
24 Vac
INPUT
1
2
3
4
5
6
7
8
9
10
24 Vac
+
DDC SYSTEM
or METER
-
ELECTRONI C MOTOR
+
or "SCR"
-
BLACK
WHITE
RED
HUMIDITY SENSOR
FOR CONTROL
24 Vac
INPUT
N/A
N/A
1
2
3
4
5
6
7
8
9
10
24 Vac
OUTPUT #2
0 to 10 Vdc
OUTPUT #1
0 to 10 Vdc
COMMON
MAIN SENSOR
+10 Vdc
Fig.4: Wiring diagram with two analog outputs
+
-
+
-
BLACK
WHITE
RED
ELECTRONIC MOTOR
or "SCR"
ELECTRONIC MOTOR
or "SCR"
HUMIDITY SENSOR
FOR CONTROL
APPLICATION EXAMPLE:
Steam humidification system controlled by a 0 to 10 Vdc valve wired to output #1. Remote humidity display using 0 to 5 Vdc signal is wired to
output #2. The humidity s ensor is located in the return air duct. A proportional high limit humidity s ensor is installed in the supply duct. An
outdoor temperature sensor is installed in the fresh air duct.
Humidistat model number: H270-69- 13-10-31
Fig.6: Application ex ample
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TABLE 2: HUMIDISTAT ACCESSORIES
H50 Internal humidity sensor for H270 humidistat and for H80 remote wall sensor.
H60 Duct humidity sensor to mount directly onto the back of any H270 humidistat.
H71 Duct humidity sensor to mount directly onto the supply or return of the ventilation duct.
H80 Wall humidity sensor to mount in any remote location.
S71 Outdoor temperature sensor to lower the setpoint in cold season.
H263 Programming tool for troubleshooting, viewing and modifying humidistat parameters.
008-0089 Replacement lexan (cover sticker) for H270 humidistat.
024-0048 Humidistat replacement base with connector (H50 internal humidity sensor not included).
H50 INTERNAL SENSOR H60 DUCT SENSOR H71 REMOTE DUCT SENSOR
This humidity sensor can be
mounted directly on 024-0048
humidistat base.
H80 REMOTE WALL SENSOR S71 OUTDOOR
This humidity sensor can be wall
mounted in any remote location.
The humidistat may be located
on the duct or other location, with
humidity sensing from the H80
sensor location.
This humidity sensor can be
mounted directly onto the back of
any H270 humidistat, with the
supplied hardware. This
transforms the humidistat into a
duct-mounted humidistat.
TEMPERATURE SENSOR
This outdoor temperature sensor
is used to lower the humidity
setpoint to prevent condensation
on windows and structures. It is
usually installed in the fresh air
duct.
WARNING:
This humidity sensor can be
mounted directly onto the supply
or return of the ventilation duct.
The H270 may be located on the
wall with humidity sensing from
the remote H71 sensor location.
H263 PROGRAMMING TOOL
This tool is used to change
humidistat parameters. It is also
useful for troubleshooting. Just
plug it in the humidistat through
the casing. See page 6 for more
details.
All H270 humidistats are intended to control equipment under normal operating conditions. Where failure or malfunction of H270
series humidistats could lead to an abnormal operating condition that could cause personal injury or damage to the equipment or
other property, other devices (limit or safety controls) or systems (alarm or supervisory) intended to warn of, or protect against,
failure or malfunction of H270 humidistats must be incorporated into and maintained as part of the control system.
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CONTROL SCHEMATIC:
100%
OUTPUT #2
HUMIDIFICATION
HUMIDIFICATION
Fig. 7 Control schematic
100%
OUTPUT #1
35%30%
d2
pb
0%
SET POINT
100%
OUTPUT #2
DEHUMIDIFICATION
0%
d2
100%
OUTPUT #1
DEHUMIDIFICATION
0%
0%
45%40%
50%
55% 60%
65%
70%
db
pb = proportionnal band
d2 = differential between output #1 and #2
db = dead band between humidification
and dehumidification
FIGURE 8: HUMIDITY SETPOINT RESET BY OUTSIDE TEMPERATURE
HUMIDITY SETPOINT RESET BY OUTSIDE TEMPERATURE
The H270 humidistat has an optional outdoor
temperature sensor. This sensor is used to reset
the humidity setpoint during the cold season to
minimize condensation on windows and building
32°F
14°F
-4°F
-20°F
-40°F
OUTSIDE AIR TEMPERATURE
HT = 32°F
LT = -20°F
USER
SETPOINT
rE = 20%
structures.
When the outdoor temperature falls below the
selected high temperature, parameter HT (32°F in
the example Figure 8), the humidity setpoint will
start to decrease. The lowest humidity setpoint will
be reached at selected low temperature,
parameter LT (-20°F).
The setpoint decrease from original setpoint down
to the lowest setpoint determined by the parameter
rE. In the example, Figure 8, rE was set to 20%,
therefore the humidity setpoint dropped from 45%
20%
25%
30% 40%
35%
%RH
45%
to 20%.
If you don’t use the outdoor reset feature, put a
jumper between terminals 6 and 9 (supplied with
rE, HT, LT
Note:
parameters can be changed with C263 programming tool
the humidistat.)
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TABLE 3: H263 HUMIDISTAT PROGRAMMING TOOL
CODE VALUES DEF AULT
Db 0 to 40 % R.H. 25% R.H. Dead Band between humidification and dehumidific ation.
SL 30 to 100 % R.H. 85% R.H. Supply Limitation: High humidity limit in the supply duct (H270 only)
d2 0 to 199 % (of proport ional
Pb 0 = 1.6 % R.H.
o1 0 = Humidific ation
o2 0 = Humidific ation
cc 2 = Without integral
t1 0 = On/off
t2 0 = On/off
rA 0 = °C
Ca
hA 0 à 127 "Hardware ass embly" Code related to thermostat model and entered at initial setup at
it 1 to 99 = 1 TO 99 MINUTES 60 "Integral time" Error integration time.
band)
1 = 3.2 % R.H.
2 = 6.4 % R.H.
3 = 12.8 % R.H.
4 = 25.6 % R.H.
1 = Dehumidification
1 = Dehumidification
3 = With integral
1 = 8 minutes
2 = 1 second
1 = 8 minutes
2 = 1 second
1 = °F
± 13 %
VALUE
100% Differential for output #2": Shift f or output 2 r elative to output 1
2= 6.4%
R.H.
3 "Control Code"
1 DO NOT
CHANGE
DESCRIPTION
Proportional Band
"Output #1" Action for output no 1
"Output #2" Action for output no 2
"Time #1" Time period for output no 1
"Time #2" Time period for output no. 2
"Range" Temperature Scale
Calibration ( deviation mode: DO NOT MODIFY: USE AUTOCAL PROCEDURE; FOR
H100 TRANSMITTER, USE THE ZERO POTENTIOMETER ON THE TRANSMITTER.
the factory.
Lt -40 à +40 °C (-40 à 105 °F) -20 °F "Lower temperature" minimum outside temperature for setpoint reset (model H270 only)
Ht -40 à +40 °C (-40 à 105 °F) 32 °F "Higher temperature" maximum outside temperature for s etpoint reset (model H270
rE 1 à 99 % R.H. 20 % R.H. "Reset” Minimum humidity value ( % HR ) (model H270 only)
only)
Example: rE = 20%. Humidity setpoint will be reset from s elected setpoint to 20%, f rom H t
to Lt
AIR SUPPLY HIGH LIMIT HUMIDITY SENSOR
The H270 includes a high limit circuit. This allows the
use of a second humidity sensor to limit the humidity in
100%
the supply air. Input signal goes to terminals #8 on the
humidistat. High limit setpoint is preprogrammed at
85%. It can be readjusted using the C263 service tool.
50%
If you don’t use the high limit feature, connect a 4.7
Meg Ω, ¼ watt resistor between terminals 8 and 10
0%
(supplied with the humidistat.)
Remember: this high limit function is not a safety
device. For critical situations, provide installation with
normal protections required to ensure a safe operation.
CONTROL OUTPUT LEVEL
SUPPLY HUMIDITY
TABLE 4 Example showing proportional high limit
override signal in supply duct.
85%
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AUTOCAL PROCEDURE
1. Measure the room humidity near the Viconics humidistat
with an accurate hygrometer.
2. Turn the humidistat set point dial to match the reading of
the hygrometer.
SENSOR FAILURE PROTECTION
The sensor is the most sensitive part of the humidistat and
also the most exposed. In the case of a sensor failure in
humidification mode, the H200 will automatically assume a
failsafe output of 0%.
3. Push and hold the Autocal button for more than 3
seconds or until the internal red light turns On and Off.
SPECIFICATIONS
Operating Conditions: 5 °C to 50 °C ( 32 °F to 122 °F )
•Control: 0% to 95% R.H. non-condensing
•Sensor: 0% to 100% R.H. (see Note 1.)
Resolution: ± 0.1 %
Repeatability: 0.5 %
Outputs: Isolated Triac: 30 Vac at ½ A max.*
0 to 5 VDC into 1KΩ resistance min.
0 to 10 VDC into 2KΩ resistance min.
0/5 VDC at 20 mA max.for both outputs
Power: 24 VAC -15%, +10%; 50/60 Hz; 2 VA
Accuracy and sensor interchangeability:
± 2 % R.H. from 0 to 100 % R.H.
Base and casing: Off-white; self extinguishing
Range: 10 % to 90 % R.H. for 5 to 50 °C
(41 °F to 122 °F )
* Triac outputs can only switch AC loads. Use relays when
switching dc loads.
Temperature effect: 0.05 % / °F
Note 1. Humidity sensor: Solid state humidity sensor.
Suitable for normal, clean air. Not to be used in corrosive
or harmful environment.
DIMENSIONS
Wiring from top
Security screw
3.275" [83mm]
1.275" [32mm]
Fig.9: D imens ion drawing
Note: Specifications and equipment are subject to change without prior notice.
Wiring from back
Cover
2.8" [71mm]
Base
"Autocal" button
1.00" [25mm]
1.275" [32mm]
2.8" [71mm]
1.60" [41mm]
(Invisib le)
4.5" [114mm]
2.0" [50.8mm] 3.77" [95.8mm]
0.9" [22.8mm]
Cover
ABS plastic
TABLE 5: SENSOR
CHARACTERISTICS
Voltage between black and white
wire, terminals #6 and #7
HUMIDITY SENSOR OUTPUT
0 % 1.05 V
5 % 1.19 V
10 % 1.34 V
15 % 1.48 V
20 % 1.63 V
25 % 1.77 V
30 % 1.92 V
35 % 2.06 V
40 % 2.20 V
45 % 2.35 V
50 % 2.49 V
55 % 2.64 V
60 % 2.78 V
65 % 2.93 V
70 % 3.07 V
75 % 3.21 V
80 % 3.36 V
85 % 3.50 V
90 % 3.65 V
95 % 3.79 V
100 % 3.94 V
Viconics Electronics Inc.
9245, Langelier Blvd, St-Leonard, Quebec, Canada H1P 3K9
www.viconics.com
sales@viconics.com
LIT-H270X-E03 H270.doc
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