Viconics H270 User Manual

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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