Ewelly EW-M801AH temperature controller review and manual

In this post will describe my experience with the thermostat EW 801AH from the Chinese company Ewelly which I bought to switch the temperature difference in the article you will read my review, the diagram of how to connect and set the thermostat + all technical parameters.

801AH is useful thermostat from Ewelly , if it needs to switch according to temperature differences, the device also combines the functions of a classic temperature controller . The thermostat compares the temperature between the two sensors and switch one relay according to the set temperature difference.

Is good to use as solar temperature controller for pump control:

Where you set the desired temperature difference, for example if the water in the solar collector heats up, the thermostat sensors detect the temperature difference if it is equal to or higher than you set the thermostat activates the relay and turns on the circulation pump which delivers hot water from the solar collector to the hot water tank

My verdict:

I started testing the Ewelly EW-M801AH thermostats in 2021 so far they work OK. The Chinese manual is quite problematic, according to it I can’t set the thermostat, so I created a complete manual below which works if you need to ask in the comments.

Here is pros :

  • Good price (about 20usd0)
  • Combines a differential thermostat with a normal thermostat such as the MH1210w
  • Allows you to set the hysteresis for the temperature difference
  • Dimensions are compatible with other thermostats

Here is cons:

  • The biggest disadvantage is the manual was packaged only in Chinese everything i had to slowly step by step find out below is my manual for EW-M801AH I hope it helps.
  • Value can be set ony 1 °C steps.
  • It takes a while to set up (a menu style similar to the STC1000 would be easier)

Schematic and Manual with instructions how to plug and set temperature controller

In the manual I will first show how to connect the thermostat then I will describe the detailed functions

Here is schematic :

CHere is simple schematic diagram for EW-M801Ah temperature controller
original schematic

Controll buttons:

  • SET button for SET temperature on relay 1 for load1
  • Arrows for increase and decrease temperature , enter in main menu.
  • Display show temperature in whole values without a decimal point such as 26°C.
  • The decimal point in the lower right corner indicates the status of relay1, if the dot is lit relay1 is on, off relay 1 is off
  • LED1,2,3,4 signal menu items (hysteresis difference and the like, exactly described below in the manual) LED1

How to temperature zone1:

  • Temperature 1 set goal temperature for temperature zone1 where we assume a lower temperature compared to temperature zone 2.
  • Press the SET button and use the arrows to set the target temperature.

How to set temperature zone2 and other options:

When the temperature reaches the set value, it automatically runs the pump circulation, makes the two temperature zones the temperature balance is reached, the electric heater controls another way

Pressing the up arrow + down arrow at once for 6 seconds to enter the menu:

LED 1 is on
If the thermostat detects two different temperature zones, and the difference is greater than the value for start, the thermostat turns on the relay, operating in the temperature range + 1ºC to + 50ºC. The thermostat switches Relay 2 if the temperature at sensor 2 is higher than and at sensor 1 by the set value.

LED 1 and 2 light up
Hysteresis for temperature difference: sk the temperature difference (between sensors) is less than the set value the thermostat switches off relay2, if you set the value 0 relay2 will always be on.

LED items 3-4 light up
The value must be higher than the set temperature difference (LED1 is lit). The same temperature at sensor2 or lower value automatically starts relay1. Relay 1 switches off if the temperature at sensor2 exceeds the set temperature in temperature zone1 by the value set in this menu.


LED 2 is light up .
The hysteresis value is the thermostat relay being switched on again or by how much the temperature can drop from the set temperature for the thermostat to switch on the relay. The hysteresis range is 1-20ºC


Temperature calibration for high temperature zone LED 3 lights up:
If you find a temperature deviation, you can shift the temperature in -10ºC by + 10ºC
Temperature calibration for low temperature zone LED 4 lights up:
If you find a temperature deviation, you can shift the temperature in -10ºC by + 10ºC


Detection of a disconnected sensor for the EH high temperature zone
Detection of a disconnected sensor for the EL high temperature zone

The products are used in solar water heater equipment, the temperature difference and temperature to control the output. It is equipped with two output controls, temperature difference control two temperature zones. When the temperature reaches the set value, it automatically runs the pump circulation, makes the two temperature zones the temperature balance is reached, the electric heater controls another way When solar heating has not reached the set temperature, the electric heating system can automatically start heating to the set temperature, temperature difference control and automatic constant temperature in range. 1

Technical parameters:

  • Working Voltage: AC220V ±10%(50Hz/60Hz)
  • Output Load: 5A/220V/AC
  • Power Consumption: ≤3W
  • Heating Control Range: 2℃~99℃
  • Temp. Difference Start Control: 3℃~50℃
  • Resolution: 1℃
  • Precision: ±1℃
  • Input Signal: 2-channel sensor, 20KXb1.5MX2
  • Size: 76*76*35mm/2.99*2.99*1.37inch
  • Operating Temperature: -10℃~50℃
  • Operating Humidity: RH≤90%

Package Included:
1 x Temperature Controller
2 x Sensor Probes

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