From one plug to three: how Baltic and Finnish households scale spot-price automation (and make an old heater smart)
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Look at our order list for September–October 2026 and a pattern appears: a customer in Ogre, Latvia, buys one plug on 9 October and three more on 29 October; a household in Hyvinkää, Finland, orders two at once; customers in Roja (Latvia) and Vilnius buy the Smart Thermostat with External Sensor to put behind heaters they already own. Nobody told them to do this. The boiler is the entry point, and then the rest of the house follows. This article is about that second step.
The customer's problem
After the boiler, the next big consumers in a Baltic or Finnish home are electric heating and, increasingly, an EV charger. Heating is different from a boiler: you cannot simply run it three hours a night, because the room has to stay at a temperature. Many households also have perfectly good "dumb" heaters, oil radiators or convectors with a mechanical dial, and do not want to replace them to get app control and price awareness.
What customers did
Three configurations we see in the orders: (1) one plug per appliance with Cheap Mode "Working hours" for storage-type loads (boiler, towel dryer, EV charger overnight); (2) a plug with the "Price threshold" condition on a heater: the heater runs normally but is switched off (or limited to 50%) while the exchange price is above the limit you set; (3) the Smart Thermostat with External Sensor behind an existing heater: the socket switches the heater by room temperature measured by a wireless sensor placed where you actually sit, not next to the radiator.
Benefit for the customer
One app, one logic, every big load. The boiler and the charger run in the cheap intervals; the heaters hold the room temperature but avoid the expensive peaks; the old radiator gets a schedule, remote control and a real room thermostat for €55 instead of a new heater. Two plugs in the cart get 5% off automatically, and parcel-machine delivery is free from €60 (Estonia, Latvia, Lithuania, Finland).
Technology used
GPO Smart Plug: 16 A, Wi-Fi and Bluetooth, Cheap Mode with two conditions (Working hours, Price threshold), duty-cycled power levels 0/25/50/75/100% for soft-limiting resistive heaters, grouping of several plugs under one tap, weekly schedules and timers. Smart Thermostat with External Sensor: the same socket platform plus a BLE temperature and humidity sensor. The sensor is our own design on a PHY6222 (PhyPlus) chip; it broadcasts readings as Bluetooth advertisements every 5 seconds, and the socket, our heaters and our thermostat boards all receive them directly, so no hub or pairing procedure is needed. Supported price areas: Estonia, Latvia, Lithuania, Finland (Nord Pool day-ahead; Sweden, Norway and Denmark are listed as compatible markets).
Improvements and know-how
Two lessons from multi-plug households. First, heaters should use Price threshold, not Working hours; several customers initially applied the boiler recipe to a heater and were surprised that the room got cold at 07:00. Our setup guide now says so explicitly. Second, a wireless sensor placed at desk height, two metres from the heater, keeps the temperature where the person is, which is the main reason customers buy the thermostat version for workrooms.
What's next
Group-level Cheap Mode (one price rule for all plugs in a room), a "house view" of consumption per appliance per cheap window, and translated setup guides in ET/LV/LT/FI. On the hardware side, the sensor is already shared across plugs, heaters and thermostats, so adding a second device to an existing GPO home is a 3-minute job in the app.
FAQ
Can I run a heater on "cheapest hours"? You can, but use Price threshold instead: the heater keeps the room warm and only pauses or throttles when electricity is expensive.
Does the thermostat socket work with any heater? With any plug-in electric heater up to 3 kW (16 A) that returns to "on" when power is restored, which covers most oil radiators and convectors with a mechanical thermostat.
Do I need a hub for the sensor? No. The sensor broadcasts over Bluetooth every 5 seconds and the socket listens directly.
Where to get it
- GPO Smart Plug — €35
- Smart Thermostat with External Sensor — €55
- BLE Temperature & Humidity Sensor — €25