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Calypso Water Heater Controller – Everything you need to know

The Calypso water heater controller installed on the electrical connection of a residential water heater.

Designed and manufactured entirely in our Saint-Jean-sur-Richelieu facility, the Calypso smart water heater controller lets you remotely control the power supply of your water heater, not the temperature of the water in the tank*. The device has been designed to help you save money and energy while maintaining optimal comfort. 

Many questions surrounding this product have been asked to our team, and we’ve decided to answer them in this blog post.

Peak event management

The Calypso water heater controller is an essential ally in maximizing savings during peak demand events under dynamic pricing programs offered by electricity suppliers. Its addition to the Éco Sinopé feature is worthwhile for all Neviweb users.

Q: How does Calypso work during a peak event?

A: When your Calypso water heater controller is participating* in a peak event, the « link » LED flashes green and the DR icon appears on the product page in the Neviweb app.

Requirements for Calypso to participate in a peak event:

  • For the water heater controller to participate in a peak event, the tank temperature must be above 45°C. If the temperature is below 45°C, the Calypso (RM3500ZB/RM3500WF) will be displayed as Not participating in Éco Sinopé and will remain non-participant for the duration of a peak event. 
  • You must have the low water temperature protection setting enabled in Neviweb for Calypso to participate in the peak event. 
  • If you have chosen to disconnect the temperature sensor, this condition – low water temperature protection – is ignored and the device will participate in the peak event.

*By participating, we mean that the water heater controller will turn off the power to the hot water tank during the peak period, and then turn it back on at the end of the peak event.

Q: Why was my water heater controller excluded from a peak event?

A: Here are the main reasons for this situation:

  1. If the water temperature drops below 45°C during a peak event, the RM3500ZB/RM3500WF will reactivate the electricity to the water heater for safety and comfort. The controller will remain non-participating for the duration of the peak period. If the temperature sensor is disconnected, this condition is ignored. For more information, click here.
  2. If you have connected the temperature sensor to Calypso, but have not enabled the low water temperature protection setting in the device configuration in Neviweb, the water heater controller will not be able to participate in a peak event. 

Note: The Éco Sinopé feature overrides all other programming. The participation of a device in a peak event is not canceled by the reception of a Zigbee command, whether it is a schedule or an automation. Thus, at the end of a peak event, this value will determine its return state.

Q: How do I exclude the water heater controller from a peak event?

A: It is possible to cancel the water heater controller’s participation in a peak event at any time, either by using the ON/OFF button on the product or in the Neviweb app. The unit will remain non-participating for the duration of the peak event.

Safety and savings

Q: Is it worth turning off the water heater at night?

A: It’s not recommended to turn off the water heater at night, because when it’s off, the water temperature in the tank slowly drops. As a result, it will have to use more energy in the morning – for a shorter period of time – to heat up to a safe temperature for use. The energy required to heat the water when the appliance is reactivated cancels out the minimal savings that could have been achieved. There’s no monetary advantage to turning off the water heater at night.

In addition, it’s not recommended to turn off the water heater at night, or to run it on a timed schedule, to protect it from potential bacterial growth. 

Ultimately, the best way to generate savings with Calypso is to use it with the Éco Sinopé feature, which works in conjunction with Hydro-Québec’s dynamic pricing to control energy demand during peak periods.

Q: Do you have any data on the savings achieved with Calypso?

A: The savings generated by the Calypso water heater controller depend on several factors. Water heater size, usage, participation in peak events, and the temperature of the room in which the tank is located can all influence the savings. Several customers have told us that the savings realized after one year of use have surpassed the amount paid for the product, particularly thanks to the use of the Éco Sinopé feature.

As for turning off the water heater during a prolonged absence (more than 3 days), it is possible to save between 2 and 3 kWh per day.

Q: Is the Calypso controller safe to prevent the development of legionella bacteria?

A: The Calypso water heater controller features a sensor (AC3500-01) that ensures a minimum temperature threshold to limit bacterial growth. The Neviweb app also includes a Low Water Temperature Protection setting which, when activated, will restart the water heater if the water temperature detected by the probe drops below a predetermined threshold (between 45°C and 55°C). 

Please note that if the temperature sensor is not connected to the Calypso, the protection will no longer apply, and the water heater may then remain deactivated for a longer period (e.g. prolonged absence).

If you turn off your water heater for an extended period, be sure to let the water warm up when you return before consuming it. Here’s a table from the Institut national de santé publique du Québec indicating the time required to eliminate the bacteria, depending on the temperature of the water in your water heater:  

Temperature (°C)

Time required (minutes)









Compatibilities and installation

Calypso installation
Photo credits: Studio Point de Vue / Guillaume Gorini

Q: Is my water heater compatible with Calypso?

A: The Calypso smart water heater controller is compatible with electric water heaters up to 20.8A (@ 240V). 

To determine the amperage of your water heater, you can use the following formula:

Amperage = Power in watts / Voltage (Ex: 4500 W / 240 V = 18.8 A)

Q: What's the difference between the Wi-Fi and Zigbee models?

A: Here is a table showing the main differences and similarities between the two products: 




Compatible with
Éco Sinopé



Communication protocol

Zigbee 3.0 

Wi-Fi IEEE 802.11 b/g/n

Required gateway



Temperature sensor



Water detection cable

Not included

Not included




Consumption graphs




Consumption graphs

Compatible platforms*


Amazon Alexa

Google Assistant


Apple Home

Amazon Alexa

Google Assistant

*Please note that features may vary from one platform to another. Please refer to the product specification pages to see the different features offered.  

Q: Can Calypso be installed by an electrician or plumber?

A: This controller must be installed by a certified electrician to comply with local and national electrical codes.

Refer to our interactive map to find an installer in your area.

Q: Is Calypso compatible with my GT125 (Mi-Wi) gateway?

A: The Zigbee water heater controller (RM3500ZB) is not compatible with the GT125 gateway, since the two devices do not use the same communication protocol. The Zigbee controller requires the GT130 gateway.

On the other hand, the Wi-Fi water heater controller does not require a gateway to operate, so it can be added to an existing ecosystem of Mi-Wi devices.

Water detection

Q: Can Calypso be linked to my Sedna Wi-Fi smart valve?

A: It is not possible to link the Calypso water heater controller to the Sedna Wi-Fi valve (VA4220WF/VA4221WF). As a result, you will not be able to shut down the Wi-Fi valve if the water detection cable connected to your Calypso senses a leak. You will only be notified of the leak via email or push notification. 

If you want your Wi-Fi valve to shut off the water in case of a leak from the water heater, we recommend that you install the detector with perimeter cable (WL4210C) around your water heater instead of the water detection cable (AC4200C-02) that can be connected to Calypso. Note that the power supply to the water heater will not be cut off in this situation.

Water detection cable on water heater

A worthwhile device

Hot water consumption accounts for 20% of the electricity bill and is the 2nd largest source of electricity consumption in the home, which is why it’s a good idea to control your water heater with a device like Calypso. The product will optimize your comfort and savings, whether it’s to automate water heater management during peak events or even for remote control of the water heater at the cottage.

*To set the water temperature in the water heater, you need to adjust it directly on the tank thermostat.

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