The XH-M452 Dual Temperature & Humidity Control Module is well suited for egg hatcheries, plant grow chambers and other enclosed spaces where you need to monitor and/or control both temperature and humidity of the air within the chamber
KEY FEATURES OF XH-M452 TEMPERATURE & HUMIDITY CONTROL MODULE:
3-digit displays of current temperature and humidity
Operates in heating or cooling modes of operation
Operates humidity and dehumidify modes of operation
AM2120 temperature / humidity sensor w/ 36″ cable.
Temperature range -40 to +60°C with ±0.5C accuracy
Humidity range 0 – 99.9% RH with ±3% accuracy
Relay switches up to 120VAC @ 10A or 15VDC @ 10A
12V module operation
The XH-M452 module provides two separate control circuits with one based on temperature and the other based on humidity. The relays associated with each circuit can be programmed to activate or deactivate based on user programmed settings.
The temperature circuit can be used to control an AC or DC based heating or cooling element like a heat lamp or fan. The humidity circuit can be used to control an AC or DC based humidifier, dehumidifier, fan, water pump or other humidity control element.
The relays are used to make / break the hot lead connection to the device(s) being controlled. In the case of 120VAC, the black LINE is run through the relay while the white NEUTRAL and any GROUND leads connect directly to the device.  In the case of 12VDC for instance, it would be the 12V hot lead going through the relay while the GROUND is wired directly to the devices and do not pass through this controller.
The AM2120 capacitive humidity/temperature sensor is on the end of a 1 meter / 3 foot cable. The cable is 4 wires, but only 3 are used. The sensor has a 3mm hole on the end for mounting. In most cases, mounting the sensor vertically such as on a wall gives the best reading. If heavy condensation is possible, it may be preferable to mount the sensor horizontally facing down to help keep water from collecting in the sensor and causing damage.
Air circulation within the enclosure is typically needed to ensure the sensor is reading the overall conditions within the enclosure.
A red LED on the left side lights when the temperature relay is energized.  A green LED on the right lights when the humidity relay is energized.
Module Power
The module itself is powered from 12VDC which is connected to the center screw terminal block.  It draws approximately 100mA when both relays are energized.  This power can come from an AC wall adapter or similar power source.  If you are using 12VDC in your switching application, the module can be powered from the unswitched side of that power supply.
Display
The module has two 3-digit displays composed of 0.36″ high 7-segment displays.
The left red display normally shows current measured temperature in °C while the right blue display shows current measured humidity in % RH.
When programming settings, the display will flash and show the current setting.  Once you stop pushing buttons, after about 2 seconds the display will default back to displaying the current measured temperature or humidity and the setting will be automatically saved.
If you apply power to the module without the sensor attached or the sensor is defective or has a broken wire, it will display ‘LLL‘.
A display of ‘HHH‘ indicates the reading has exceeded the displays capability.
Buttons
There are 4 buttons on the module that you can fiddle with.  They are labeled in Chinese, so refer to the picture above for their functionality.
As might be expected, when changing settings the ‘+‘ increments the setting while the ‘-‘ decrements the setting for either temperature or humidity.
To restore to default factory settings, press both the two inside buttons (temperature – and Humidity +) for several seconds until the displays show ‘888 888’.
The default factory settings are to turn ON the temperature relay at 20°C (68°F) and turn it OFF at 30°C (86°F).  The humidity relay is set to turn ON at 47% and turn OFF at 60%.
Button Operation
Temperature +
Short press to display current ON temperature
Long press (2 seconds) to set ON temperature.
Display will flash.
While display is flashing, the +/- buttons can be used to adjust the temperature relay ON setting up or down.
After no button activity for a couple of seconds, the display will stop flashing and the setting will be automatically saved.
Temperature –
Short press to display current OFF temperature
Long press (2 seconds) to set OFF temperature.
Display will flash.
While display is flashing, the +/- buttons can be used to adjust the temperature relay OFF setting up or down.
After no button activity for a couple of seconds, the display will stop flashing and the setting will be automatically saved.
Humidity +
Short press to display current ON humidity %
Long press (2 seconds) to set ON humidity %.
Display will flash.
While display is flashing, the +/- buttons can be used to adjust the humidity relay ON % setting up or down.
After no button activity for a couple of seconds, the display will stop flashing and the setting will be automatically saved.
Humidity – 
Short press to display current OFF humidity % temperature.
Long press (2 seconds) to set OFF humidity % temperature.
Display will flash.
While display is flashing, the +/- buttons can be used to adjust the humidity relay OFF % setting up or down.
After no button activity for a couple of seconds, the display will stop flashing and the setting will be automatically saved.
Controlling Temperature
Heating mode:
The ON temperature is set lower than the OFF temperature and the relay is energized to turn ON a heating device of some type such as a heat lamp which goes back off once the OFF temperature is reached.
Cooling mode:
The ON temperature is set higher than the OFF temperature. The relay is energized to turn ON a cooling device of some type such as a fan. It turns back off once the OFF temperature is reached.
Controlling Humidity
Humidify Mode:
The ON humidity is set lower than the OFF humidity level.  The relay is energized to turn on a humidity increasing device of some type such as a humidifier that is turned back off once the higher OFF humidity level is reached.
Dehumidify Mode:
The ON humidity is set higher than the OFF humidity level.  The relay is energized to turn on a humidity lowering device such as a dehumidifier which is turned off once the lower OFF humidity level is reached