October 18, 2022, 10:15 am | Read time: 5 minutes
Connected thermostats promise significant savings on annual heating costs and offer practical additional features. But can the purchase costs be recouped?
This coming winter, many consumers want to keep heating costs as low as possible. Given the drastically increased energy prices, this is a necessity for many households. Programmable and smart thermostats for radiators are said to potentially save up to 30 percent on heating costs. A fact check.
Smart Thermostats: What Are They Exactly?
They function essentially like the usual rotary controls, only electronically. The valve on the heater is opened and closed with a small electric motor. A control electronics monitors the temperature and maintains the connection to the control center. Depending on the manufacturer, this can be a standalone box or the internet router. Such a thermostat costs between 40 and 70 euros.
How Can You Program the Thermostat?
With a programmable thermostat, measuring the room temperature and controlling the radiator valve is automated. You can, but don’t need to, manually adjust the temperature each time. You program the times and days when the temperature should be higher or lower directly on the device.
For example, you can set normal temperature from Monday to Friday from 2 p.m. to 10 p.m. and from 8 a.m. to 10 p.m. on Saturday and Sunday. At all other times, the room is heated less because the residents are in bed or usually not there. If something changes or you feel too cold or too warm in between, you can make adjustments.
Related: Smart Thermostats Tested – Which Ones Are Worth It?
How Much Do the Devices Cost?
According to Volker Meyer from the German Engineering Federation (VDMA), basic programmable thermostats are available from 10 to 15 euros. Simple smart thermostats cost between 40 and 70 euros. But for extras like window sensors or control centers, a household should budget between approximately 400 and 800 euros for a starter package with six thermostats, four window sensors, and a control unit, according to Stiftung Warentest, a German consumer organization.
Related: Smart Home Association Chief Warns Against Products from the U.S. and Far East
Can I Really Save on Heating Costs with Smart Thermostats?
Not necessarily. Energy and heating technology expert Matthias Wagnitz from the ZVSHK industry association is skeptical. He says, “How much you can save also depends a lot on how you heated before.” In other words, if you’ve always turned down the heat at night and don’t leave it on high during the day, you might save less than those who like to sleep warm and sometimes heat with the window open.
Living Situation Is Key
Your living situation is crucial. You might have central heating, a floor heating system, or night storage heaters, which often can’t integrate such devices. You could live in a well-insulated home or one that’s poorly insulated.
Homeowners might have old boilers with cast-iron radiators, a condensing boiler, or low-temperature heating systems. There are so many possible scenarios that blanket savings promises are not very credible.
Related: Smart Home Association Chief Warns Against Products from the U.S. and the Far East
Can Smart Thermostats Really Save on Heating Costs?
Not really. For the example apartment, it’s effective, and ZVSHK expert Wagnitz also says: For renters, the calculation is only partially applicable. Homeowners can usually set a night setback directly on the boiler, says Matthias Wagnitz. They might save a bit more with smart systems by adjusting heating times for individual rooms–for example, heating the bathroom only in the morning. But you can’t calculate such savings across the board.
For example, the German consumer organization Stiftung Warentest conducted a sample measurement in 2019 (apartment building, 70 square meters, six heaters, poor insulation) and found a savings potential of about eight percent if you lower the temperature at night or when absent. After deducting basic costs, six percent remains. That’s about 60 euros saved annually, assuming heating costs of 1,000 euros per year.
Also of interest: How to Heat Economically Without Sacrificing Comfort
Replace Old Thermostats on Heaters to Save Energy
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When Do Smart Thermostats Pay Off?
Possibly never. If you calculate 300 euros for the purchase of thermostats for the six radiators in the example apartment, you might break even after five years in the best-case scenario. Additionally, with the thermostat, you can only reduce consumption costs. Unfortunately, the smartest thermostat doesn’t change the basic fees for reading, billing, shared costs for stairwells, or floor space shares. And no two winters are alike.
Furthermore, many systems have monthly costs for using additional features. According to Nico Jurran, there are also potential costs for extra temperature sensors, which can help better adjust the often imprecise temperature control directly at the thermostat with additional data from the other end of the room.
Do I Even Need Connected Thermostats?
The simple answer is no. You can also reduce heating costs by using your rotary controls. The Consumer Center of Mecklenburg-Vorpommern, a German consumer organization, recommends setting the temperature to 21 degrees Celsius in frequently used living spaces and 18 degrees for bedrooms. Rooms should not be kept below 16 degrees for extended periods to prevent increased humidity and mold growth.
When set up correctly, they are extremely comfortable, and they offer more than just potential savings. You can build smart circuits with window contacts–then the heating turns off when you ventilate, for example.
As Reiner Metzger says, “The great advantage of smart thermostats is that you can control the temperature for each radiator individually.” This is also practical for centrally controlled heating systems, allowing everyone to have customized heating times for different rooms.
When the heating is off, many solutions regularly open and close the valves. This prevents calcification. Once set up, you hardly have to worry about the heating anymore. While it might not save money, it might prevent some arguments with housemates, which is also valuable.
with material from dpa