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For this solution, we are using a Sonoff SV controller. This is a nice controller since it has everything we need to control the heater's remote relays. Additionally, we can power it from the heater itself since it accepts 5-24 volts input and the heater will supply us with 10v. We are going to use the Sonoff SV in isolation mode by removing the two resisters that would normally supply the power to the controller using the input voltage.

Firmware

Flashing

Once the flashing is complete, it will reboot.  You will need to look for pool-heater, in your list of available WIFI networks.

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In the Apple Home App we now have access to our pool heater.

Wiring

Wiring Diagram

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Board Pinout

Wiring Pictures

Temperature Sensor

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• Press Up or Down to display REMOTE.
• Press MENU, REMOTE OFF (default) is displayed.
• Use Up or Down to scroll through the Remote options until HI-LO-COM is displayed, then press MENU to select.
• Press POOL or SPA to exit Service Setup mode

Advanced Functionality

Only Heat when the Forecast Looks Good

Using the home bridge weather plus plugin, we can pull weather forecasts for our location and then setup an automation in Apple HomeKit.

Ottawa Forecast:

https://openweathermap.org/city/6094817

Install the following plugin for homebridge:

https://github.com/naofireblade/homebridge-weather-plus

Configure it in the config.json. This plugin will add the current temperature and the forecast for today and tomorrow.

        {
                "platform": "WeatherPlus",
                "service": "openweathermap",
                "key": "xxx",
                "locationId": 6094817,
                "locationCity": "Ottawa, CA",
                "locationGeo": [45.393553, -75.700374],
                "conditionCategory": "detailed",
                "forecast": [0,1],
                "nameNow": "Ottawa",
                "nameForecast": "Ottawa Forecast"
        }

In Apple HomeKit, setup the automation:

Add an Automation and select "A Sensor Detects Something"

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Select your tomorrow's forecast (I renamed mine to Tomorrow's Forecast). Select Rises Above and choose a temperature. Restrict the time of the check. I do the check right before my pool pump is about to start it's nightly heat/filter cycle.

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Select the pool-heater and set the desired temperature and select Done.

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You are all setup!

References

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