Make an electric water heater through home automation Sonoff (Basic, or POW)

4 minutes of reading
  • A home automation actuator Sonoff Basic (o Sonoff POW, if you also want the reading of electrical absorption)
  • A common electric water heater (with absorption within the operating ranges of the Sonoff Basic - or maximum 2200 watts)

All environments

Notes and disclaimer
  • qualsiasi eventuale modifica agli impianti domestici dev'essere progettata ed realizzata SOLO da personale qualificato;
  • any changes implemented in probefore is a propersonal responsibility as well as a profirst risk and danger (the contents of the present page are purely educational);
  • any changes implemented in proprior to a device it voids the guarantee, quality approvals and certifications.
revision projet: 2.0

Small water heater


An electric water heater it is essentially a low-tech device composed of a water tank, a thermostat and a heater element. When powered, if water is found at a temperature lower than the thermostat regulation (manual), this last element procloses the circuit that supplies the electric heater, which, apptogether, heat water. When the temperature then is reached, the heater is switched off.

It is one of the easiest tools to introduce in a domestic installation and, despite is far fromenergy efficiency of other technologies, it is still today one of the most widespread tools.

Profirst because efficiency it is not very high (not to mention poor), the ignition of a water heater must be inevitable parsimonious and reasoned. One solution is to applicare a timer which, at certain specific times of the day / week, proturn on the water heater, which obviously already has the thermostat set to the desired water temperature. The continuous h24 ignition is in fact extremely expensive in terms of costs.Big water heater

Let us assume that, to take a shower, the water heater must be switched on for at least half an hour. It will therefore be necessary to switch on the water heater half an hour before of the scheduled time to wash, remembering to proset the timer. But if you are outside the home? I won't be able to turn on the water heater until I get home, forcing myself to wait for it to warm up.

The present projet approthe question in a home automation key: if we used instead of a timer a home automation actuator?

Approin this way I could control the water heater:

  • temporizzandone ignition;
  • checking its ignition remotely;

up to to more complex automations (integrating the actuator into a personale HUB):

  • timing the ignition at a certain time based on the actual presence of the tenants;
  • checking the ignition based on geographic and / or climatic events (Eg. "turn on the water heater when I leave work but only if the outside temperature is lower than 25 degrees“).
Nb. The actuator considered for this projet is the Sonoff Basic, which bears a maximum load di 2200 watts. Whatever actuator you use, it's important that the load appsilicate is less than what the actuator supports. Alternatively we suggest the Sonoff POW, analogous to Sonoff Basic but able, in addition to the functionality of a switch, to offer also that of instantaneous reading of the electric absorption.


As explained, it is therefore a question of inserting a Sonoff Basic (o Sonoff POW) upstream of the water heater inlet. This change, we remember, goes always carried out by a qualified installer.

The modification scheme is the following:

Water heater - First step
Cut the power cord and ...

Water heater - Second step
... enter the Sonoff Basic.

The result will be that theactivation / deactivation of the upstream current (through Sonoff) enable / disable the water heater.

This action can be done manually via the button on the back of the Sonoff, thus allowing the control of the water heater even in the absence of home automation and network Wi-Fi, network through which we will now go to configure (and control) the actuator itself. The fact that home automation "leaves us on foot" in his absence is alone commonplace.

Actuator configuration

Downstream of the installation (physical) of the device, it is necessary prosee it set up, or to make it "enter" into profirst network Wi-Fi so as to control it through the proman app. To do this, you need to download and install theapp"eWeLink" (For Android e iOS).

After feeding the Sonoff Basic, press the button on the back and keep it pressed for about 7 seconds: the change of the flashing of the LED will change, communicating to the user the activation of the configuration mode.

At this point (after having appurge that the smartphone / tablet is connected to Wi-Fi domestic) open theapp eWeLink and click on "Quick Pairing"

eWeLink - Pairing  1

Theapp at this point he will ask the name and password of the Wi-Fi domestic to which provide access to Sonoff Basic; subsequently, theapp "Will seek" the new Sonoff Basic to configure:

Once identified, it will ask the user to provide a name to be assigned and complete the configuration:

Finished the procedura, the Sonoff Basic will finally be controllable directly from theapp, not only Manually, but also through proming:

eWeLink - Sonoff Basic - details


We finished! Once the configuration is finished, the use will be really very simple: to turn on / off the water heater will be enough press physically the black button on the back of the actuator or, through theapp, by pressing the on-screen virtual switch, as shown in the video.

Theapp eWeLink it allows you to configure the timing and manage manual switch-on / off, all even remotely.

So far as si prosee update the Sonoff with firmware Sonoff-Tasmota it will be possible to insert the fan inside of our centralized home automation based on HUB personal such as Homebridge, Home Assistant e openHab, which opens up a whole series of extremely more advanced and efficient automations, as explained in the abstract. If the model chosen is the POW, the electric absorption readings will also be obtained.


As anticipated, it is possible to think of using the system thus automated through automation.

In case of use Appthe HomeKits, a solution is to:

If instead it is adopted, like HUB staff, Home Assistant, then the road will be that of add the Sonoff Basic to its configuration as a switch and then prosee the automation.

Water heater - functional schemenamento (thx to

ITEAD Sonoff BasicATTENZIONE: remember that there is on our FORUM community an ad hoc section dedicated to Sonoff (and more generally to devices ESP8266), for any doubt, question, information on the specific merit of these components.


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