Options for a Wi-Fi controlled Softub
This goes over possible solutions to control your Softub with Wi-Fi. There aren’t any plug-and-play solutions available right now, so all approaches require some degree of electrical, electronics, and programming knowledge.
Monitoring the temperature
If all you want to do is keep track of the tub’s temperature, then a floating wireless temperature probe is a simple solution. It is also the most accurate way of measuring it, since the built-in temperature of the Softub measures the water temperature in the Hydromate plumbing, which can be quite different from the actual tub temperature.
Basic approaches to controlling
There are a few approaches to controlling the Softub:
- Replacing the circuit board and control panel. Use a generic smart-home device, such as a Sonoff, to replace the Softub’s existing circuit board and control panel.
- Integrating with an upgraded circuit board and control panel. Use a device that works alongside the upgraded board.
- Completely custom solutions.
1. Replacing the controller circuit board
Some people use a Sonoff or another device to control the tub instead of the circuit board and control panel. It is a relatively inexpensive approach, but it requires working with mains voltage to rewire things and replacing the temperature sensor with one compatible with a Sonoff. The app is straightforward as smart-home apps go.
If your current board or control panel needs fixing or replacing, this could be a much cheaper solution. However, there are important considerations.
Safety
The Sonoff is intended for a maximum ½ hp motor, so there is a real chance that it could prematurely fail, potentially in a dangerous way. Although it is rated for 20 amps, that rating is for resistive loads. The stock control board is designed to prevent the hot tub from becoming dangerously hot: it has a separate high-limit circuit with its own relay to help ensure it does not exceed about 118°F, even when another part fails.
If a Softub gets stuck in the “on” state, it could reach unsafe temperatures, potentially damaging the tub or Hydromate, or causing scalding injuries. With a Sonoff, you are trusting a single undersized relay not to fail closed.
Improving the safety of using a Sonoff directly
Instead of directly controlling the Softub pump, use the Sonoff to turn on a contactor. A contactor is a heavy-duty relay designed to work with inductive loads. You can use two in series so that even if one is stuck, the system will not be stuck on. Other failure modes could still cause runaway temperatures, however, so this is not as safe as the original board.
Consider adding an alarm in the Sonoff app if the temperature goes over a certain point. You can also use two Sonoffs, each with a contactor, in series: one set to turn off if the tub gets too hot and one for normal control. If properly programmed and wired, the safety should be about the same as the stock board.
Ease of use
Because the Sonoff replaces the control panel, you have to use its app or another smart device rather than the buttons and display on the Hydromate. You also lose the ability to turn the Softub lights on or off unless you add another Sonoff.
2. Working with the upgraded circuit board
This requires a board upgraded with the new firmware. See the Features page for details on the improvements and how to get this for your own tub. I also offer new boards with this enabled.
Using a timer or smart switch
- Since an upgraded board returns to the last temperature set rather than returning to 100°F, you could simply plug the Softub into a smart plug or timer.
- When the smart plug turns on, the tub returns to the last temperature. This can work well if you only want it to run during certain hours.
Integrating with the updated board
The updated board can sense on-and-off requests from devices that work with “dry” relays, such as the Sonoff Elite. Like the previous option, you could use this to run heat during certain hours while still working normally at other times.
Unlike the previous option, the control panel stays operational even when the Sonoff is off. Also, even if you lose internet, the tub continues to work normally.
Wi-Fi adapter board and smart device
The upgraded board can send the current temperature to the Sonoff, but it needs to convert the Softub’s 5 volts to the Sonoff’s 3.3 volts. A small adapter board makes that conversion and simplifies attaching the smart device.
Shelly Uni Plus
A similar solution to the Sonoff is the Shelly Uni Plus. It is easier to install because it can be placed in the controller-board box and does not require a separate power source. Its app is less user-friendly and cannot integrate the current temperature directly with Alexa, though it can display the temperature in its app or use Home Assistant as a bridge with Alexa.
Other options
If you are an electronics hobbyist interested in making something custom, see Custom options for controlling a Softub for ideas.