8/18/2019 Humidistat Report

1/14

HUMIDISTAT

8/18/2019 Humidistat Report

2/14

Humidity is the presence of water in

air.

The amount of water vapor in air canaffect human comfort as well as many

manufacturing processes in industries.

8/18/2019 Humidistat Report

3/14

Humidistats ensure a room maintains

a comfortable temperature and helps

prevent mildew from forming.

Certain rooms in a home are moresensitive to humidity and are more

prone to the development of mildew.

8/18/2019 Humidistat Report

4/14

HUMIDISTAT

-An electronic device analogous to a

thermostat, but which responds to

relative humidity, not temperature.

-An instrument used for measuring and

controlling humidity.

-Sometimes called a hygrostat.

8/18/2019 Humidistat Report

5/14

Common Uses:•Humidistat are used in a

number of devices including

dehumidifiers,humidifiers, and

microwave ovens.

• Refrigerator,greenhouse, or

climate controlled warehouse.

8/18/2019 Humidistat Report

6/14

•For Heating, Ventilating and Air

Conditioning (HVAC)of buildings.

•In some crawl spaces, the humidistatis often used to control the

ventilation fans so as to maintain

humidity at certain levels.

8/18/2019 Humidistat Report

7/14

History:•14! " the #erman $ishop %icolas of Cusa,concluded that the atmospheric humidity could

be measured.

Over the following centuries many materials

and methods were used with more or lessefficiency :

•1&!! " cat intestine e'tension by Santorio

Santorio

•1&&! " (aper strips e'tension by )olli )rancisco

•1&& " Hygroscopic salts, bending of a beard of

wild oat by Hoo*es

8/18/2019 Humidistat Report

8/14

8/18/2019 Humidistat Report

9/14

•5n 1, the first efficient electromechanical

humidistat using hair as a measurement wasinvented by Honeywell, SA.

•5n 1&, the same company replaced hairs

with a nylon ribbon

8/18/2019 Humidistat Report

10/14

Example of a Humidistat:

6igital Humidistat

8/18/2019 Humidistat Report

11/14

BASIC PARTS OF A HUMIDISTAT:

8/18/2019 Humidistat Report

12/14

1. )rame &. 7icro/switch

. Hygroscopic ribbon +. Calibration screw

. 8ever mechanism -.6ifferential ad9ustment screw

4. Ad9ustment shaft . :lectrical terminals

. (lunger 1!.2all mounting bo' ;optional<

A humidistat is composed of 10 main components

8/18/2019 Humidistat Report

13/14

MECHANISM

5n fact, the wor*ing principle of ahumidistat is very simple. 5f there are any

variations in the relative moisture, an

electrical resistance will be caused between

the conductor sets that are mounted on thesensing element.

The >uantity of the electrical

resistance can be precisely predicted by the

alternate metal conductors according to the

relative humidity.

8/18/2019 Humidistat Report

14/14

And the relay amplifier will measure the

resistance so that it can turn the humidifieron if the electrical resistance shows the

humidity doesn?t reach the optimal level, or

turn off the humidifier if the ideal level is

achieved.

The sensing element in a humidistat is

usually a band of moisture/sensitive nylon.

The nylon e'pands and contracts with

changes in the relative humidity of the air.