Humidistat Extractor Fan

A humidistat for reducing the humidity in a room.

The humidistat uses an Arduino nano, fan and motor controller, and DHT11 humidity/temperature sensor to measure and control the humidity in a room by extracting the air from the room allowing new dryer air to take its place.

There are 2 versions of the code:

• Humidistat_Extractor_Fan_V2.ino (normal)
• Humidistat_Extractor_Fan_with_Button_V2.ino (moded)

The normal humidistat will:

• Turn the LEDs on at 50%,60%,70%, and 80% relative humidity.
• Turns the fan on when the humidity is above the minimum humidity (50%), and off when below the minimum humidity.

The moded humidistat will:

• Will need a momentary button plugged into pin 10 on the arduino.
• During Mode 0 (Normal):
  • Turn the LEDs on at 50%,60%,70%, and 80% relative humidity.
  • Turns the fan on when the humidity is above the minimum humidity (50%), and off when below the minimum humidity.
• During Mode 1 (Always on):
  • Turns the fan on regardless of humidity.
• During Mode 2 (Always off):
  • Turns the fan off regardless of humidity

Parts you'll need:

• 4 m4x80mm machine screws, 10 m3x20mm machine screws, 4 m4 nuts, and 10 m3 nuts.
• 12v High Static Pressure Fan
• Arduino Nano Classic/Everday
• DHT11 Humidity/Temperature Sensor Module
• Motor Controller (either this or just a L298N on a breadboard with diodes and capacitors)
• 4 5mm LEDs
• ~12v Power Supply
• Breadboard & Wires
• Dupont Connectors
• JST Connectors
• Glue (for the LEDs)
• Momentary Push Button
• DHT11 Case

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V1.1 23/03/2024: Removed Arduino Nano mount from lid, accepted that a breadboard is probably a better idea. Added holes to secure power supply wires if necessary. Made motor controller mount holes through holes.

V2 23/03/2024: Mistakenly made bolts and nuts for lid and mount different sizes. Changed this to both be m3. Decreased width of fan hole from 128mm to 124mm to provide a better fit around the fan. Decreased fan hole size from 120mm to 115mm as fan holes are generally a bit smaller than 120mm. Added clamp for power supply wires.

V2.1 05/08/2024: Removed chamfer and fillet from fan hole as this made the seal around the fan worse. Removed text from Lid in case the lid is mounted on the side or the bottom of the fan mount. Added hole for access to the USB port on the Arduino for easier coding.

16/10/2024: Added a different code that uses a ~16mm momentary button that cycles through different fan modes (Normal, Always On, Off) when connected to pin 10 on the arduino. The button uses my PWM Fan Controller Housing as a case.

19/11/2024: Moved the DHT module out of the humidistat casing and into this casing as the motor controller was causing the humidistat casing to warm up which lowered the relative humidity which would prematurely turn the fan off.

Print Settings

Printer Brand:

Creality

Printer:

Ender-3 S1

Rafts:

No

Supports:

No

Resolution:

0.2

Infill:

20

Filament: PolyTerra PLA Pink Notes:

When printingmount using a 0.2mm layer height, pause the print at layers 67 and 267 to insert the 4 m3 nuts.

Category: Bathroom