Smart Thermostats Are Changing The HVAC Industry
What is a smart water heater? There are several answers to this question. We will try to provide the most commonly used definitions.
The first one is related to the concept of ‘'smart devices'' and the Internet of Things (IoT), meaning they are being connected to the internet and remotely controlled via mobile devices (i.e. mobile phone or tablet). This image of the smart water heater is represented worldwide, especially in the USA.
The other is related to the implementation of Artificial Intelligence (AI) concept in the HVAC industry. This means that besides the water heater can be easily programmed, it can even learn user's behavior and prepare hot water when needed, based on user preferences. This optimizes energy usage and leads to cost reduction. This definition of the smart water heater is commonly used in Europe thanks to the EU's very clear regulations regarding home appliances. The European Commission has issued several directives and introduced the phrase ‘'smart control'' - which means ‘'that device can automatically adapt the water heating process to individual usage conditions with the aim of reducing energy consumption[1]''
Probably the best answer is the combination of the previous two mentioned definitions and concepts. The smart water heater is connected, self-learning, user adaptable, and energy efficient device.
How can one conventional domestic water heater (DWH) become the smart one?
Definitely, the answer to this question lies in high-tech electronics. Most of the solutions represent some kind of smart thermostat or PCBs which can replace the conventional mechanical thermostats.
EST-100 smart thermostat for electric storage water heaters, introduced by Euroicc, combines reliable mechanics and high-tech electronics in a single device. It's a rod or stem type electronic thermostat with smart control, LCD display and Wi-Fi module that can be controlled via Android and iOS mobile apps.
EST-100 solution consists of 2 elements, connected by a quick faston connection cable. The first element is the electromechanical thermostat, which controls the heater and collects data about water temperature. The second element is electronics with LCD TFT display 1.44'', 4 buttons, user interface, and Wi-Fi module. Mobile applications, as a part of EST-100 solution, provide complete product functionality and enable remote control of the electric storage water heater. The water heaters' end-user is provided with 5 selectable operating modes and 2 background operating functions.
Is rod or stem type of thermostats the only one?
Some of the electric storage water heaters use the different type of thermostats, mostly the capillary version. The capillary solution usually consists of two units, where the first is a functional one, and the another is a safety thermostat. There are also solutions where one device comprises both kinds of thermostats.
In order to fulfill the needs of DWH manufacturers who use the conventional capillary thermostats, Euroicc is developing capillary smart thermostat product version. This solution is called EST-150 smart thermostat. The PCB is replacing the functional thermostat and the conventional mechanical safety thermostat should be kept in the water heater as an integral part of the solution. Instead of being placed in the stem, the two temperature sensors are located on the cable. Besides the safety component, this is the only difference between the EST-100 rod and EST-150 capillary solution.
What are the core values of the smart water heater concept?
Every smart water heater has to be safe, energy efficient, connected and to provide exceptional comfort to its users. These are the core values and principles of the Euroicc's smart thermostats, which are used in the development and manufacturing process.
How can smart thermostat increase the water heater's safety?
Water heater's safety is increased and provided by a bimetal disc, bipolar safety cut-out, and safety software. The safety software is responsible for electronic functional cut-off and bimetallic disc for safety cut-out. Euroicc has combined the new technology with traditional mechanical safety. This is considered to be the optimal solution since there are at least two levels of safety - if the electronics and safety software fail, the bimetal disc will cut-out the electrical supply of the heater. In every moment, thanks to the mobile application, the user has remote and complete control over the water heater.
The bipolar safety cut-out is very important since it disconnects all supply conductors, live and neutral, by a single initiating action. The bimetal disc and bipolar safety are well-known and proven in the decades of DWH practice. What sets apart the electronic solutions, like EST-100 and EST-150, is the software. The advanced software is constantly monitoring the water temperature for the user's additional safety. Two active temperature sensors in thermostat's rod are vouching for accurate temperature measurement. The thermal hysteresis loop of EST-100 and EST-150 is 4 ± 2°C /39.2 ± 35.6 °F. It can be even narrower, but the detailed laboratory tests have shown that this is the optimal tradeoff between the accuracy and relay durability.
Why is accurate and constant temperature measurement so important?
Besides the obvious answer - to prevent the possible overheating, there are less known but also important safety aspects. The first one is Anti-Legionella and the second is freeze protection function. Even the smart function and smart control would be impossible without the precise temperature measurement data.
When the water temperature doesn't reach a higher level of degrees, for a longer period of time (i.e. 70 °C/158 °F, 2 weeks in a row), the dangerous and harmful bacteria (Legionella) can flourish. If neglected, this process can be a threat to the user's health. This is why the smart thermostat will automatically activate the Anti-Legionella cycle if the heater does not reach 71 °C/159.8 °F for 15 days in a row. In Anti-Legionella cycle, the water is heated to 75 °C/167 °F for 15 minutes and this treatment will remove all potentially harmful bacteria from the water.
Another part of the safety software, constantly operating in the background, is the freeze protection function. The smart thermostat prevents water temperature to drop below 10 °C/50 °F. If the temperature falls below this level, the heater will turn on automatically and heat the water to 15 °C/59 °F. The water temperature is constantly kept at 10 °C/50 °F, in order to prevent freezing in winter periods. If there is a risk of frost, the water heater must be drained ahead of the cold season in case the appliance will not be used for several days or if the power supply is disconnected.
How can smart thermostat increase the energy efficiency?
The electronic temperature measurement with two temperature sensors guarantees the accurate water heater operation. This is fundamental for energy saving modes and smart thermostat functionalities. EST-100 and EST-150 smart thermostats have 3 energy saving modes: Eco, Timer and Smart.
In Eco mode, the water temperature is kept at 55 °C/131° F. This temperature level enables optimal long-term water heater operation, in terms of energy savings, lower heat losses, hot water availability and heating element durability. This mode is recommended for traditional usage when the water heater is left to operate continuously at one set point.
Timer programmable mode, allows the users to program the water heater in line with their needs. Water temperature can be set hourly, daily and weekly and saved as a personalized plan. The programming is done via a mobile application. The major energy savings can be made by programming the water heater to operate only when really needed and in off-peak hours.
Smart mode activates the advanced software for heating optimization, reducing energy consumption by up to 15%. The smart function enables the water heater to learn shower habits and to adjust water heating to its user's needs. This means that hot water is available when needed, but made with major energy savings. The European Commission demands at least 7% of energy savings to be gained due to smart control, under the prescribed conditions[1]. If prescribed conditions and smart control factor are fulfilled, the electric storage water heater is ‘'smart control compliant''. 
How can water heater become a smart home device?
Any electric storage water heater with EST-100 or EST-150 smart thermostat automatically becomes a smart home device. Integrated Wi-Fi module enables a wireless connection of the water heater. The remote control is provided via easy-to-use Android and iOS apps. With a cloud solution, the water heater can be connected and controlled via the internet too, providing the real Internet of Things (IoT) experience and benefits. Remote control from any location is perceived to be a major innovation in the HVAC industry and the highest added value for the end-user.
How can smart water heater provide maximum comfort to its users?
The recent water heater industry trend is digital control with user-friendly HMI. One of the main features of EST-100 and EST-150 is an advanced color LCD display with 4 buttons for easy settings and water heater control. It's important to create the innovations which are simple, intuitive and easy for everyday usage. Euroicc's in-house research has shown that displays with more than 4 buttons are too complicated for the average user. In order to provide flexibility and customization options, the buttons and display plastics can be UV printed with different logos and icons.
Even though the displays are currently the cutting edge solutions, the future belongs to the remote control and intuitive Android and iOS mobile applications. Mobile apps provide a unique water heater user experience and add a new dimension of comfortable usage. You can turn on the water heater before leaving the office, and hot shower water will be waiting for you at home. With the branded mobile apps, DWH manufacturers can stand out from the competition and increase their brand awareness. Language localization in mobile apps is also really appreciated and popular among the users.
By implementing the Artificial Intelligence (AI) concept in its products, DWH manufacturers can create added value for the users. When the smart mode is activated, the software is 2 weeks collecting data about the water temperature acquired from the temperature sensors. The collected data is being processed and applied afterward in the heating process. The heating process is being optimized according to the user's needs. Basically, the water heater is ‘'learning'' its users' shower routine and implementing it later on in its operation.
Conclusion
It's fascinating how technology changes our businesses and our lives. The new concepts like Artificial Intelligence (AI) and the Internet of Things (IoT) will shape the industries and be one of the most important growth drivers. Innovations, quick adaptation and creation of added and unique value to the user are the best ways to distinguish ourselves from the competition. The smart thermostats are changing the HVAC industry, especially the water heating segment. The only question is: are we ready to change?
Lazar Ćurčija MSc is a Product Manager for Smart Thermostats in Euroicc. Euroicc is a high-tech electronics company, with in-house development and manufacturing. Euroicc has more than 20 years of experience in building automation, PLCs, microcontrollers and smart home devices. We can help water heater manufacturers in the creation of smart, energy efficient and connected products and solutions.
