General Instructions for Themo Price Switch

Created by Themo Support, Modified on Mon, 01 Apr 2024 at 10:54 AM by Themo Support


Themo T700DIN is a DIN-mounted device that can be used for a multitude of different heating systems and electricity consumers. This article focuses on giving you an idea of how to use Themo T700DIN for controlling the heating of your water boiler in Price Switch mode. To keep things simple, we will refer to the device in this article simply as ''Price Switch''.

What is Price Switch?

Themo Price Switch is a product that is designed to shift the electricity consumption of your device (eg. boiler) to the cheapest possible hours of the day. You will get the most benefit out of Price Switch with a SPOT electricity contract, but this is not necessary. 

The main idea is simple, and after installing and configuring the device there are only a few decisions for you to make:

1) How many hours a day should my boiler be able to heat per day?
2) How many hours at most can my boiler be without heating?
3) Is there a maximum price for electricity, above which I am not willing to heat at all?

Price Switch takes these parameters into account, and creates the most cost efficient heating schedule for the day. In a nutshell the idea is to take the cheapest hours that fit these parameters, and close the relay to the heater during these hours to enable heating.

Because the final decision to heat the boiler comes from the boiler's own thermostat, it is at this time not possible to follow consumption using Price Switch. 


Price Switch is installed on a DIN-rail usually located within a circuit breaker box. Because installation requires coming into contact with 230V wires, installation can only be done by an authorized electrician. 

If you want to use Themo T700DIN in Price Switch mode, make sure not to add an external temperature sensor to it at installation. Otherwise the device will not allow you to choose Price Switch mode.

Some answers to the most frequently asked questions can be found at the end of this article.


For configuration, please refer to the following instructions:

How to connect Themo to Wi-Fi using iOS device?
How to connect Themo to Wi-Fi using an Android device?
How to connect Themo to your Wi-Fi using Web browser?
Reset and Wi-Fi configuration

These instructions are made for our wall thermostat, but are perfectly valid for configuring Price Switch aswell. 

If you encounter difficulties during the configuration process, make sure that your cellular data and VPN are turned OFF for the process. More helpful articles can be found in our knowledge base. If you are not able to solve the issue by yourself, please contact our customer support.

Controlling Price Switch

Once configuration is done, you can find your device on the main dashboard of the Themo mobile app. As mentioning earlier, using Price Switch is simple:

1) Select how many hours a day Price Switch should be ON by scrolling the control knob. 

2) Select the maximum hours how long your boiler can be without heating (Settings -> Configure Device -> Consecutive OFF max)
Note! To give Themo the most flexibility in delivering savings, we recommend to set this option to 24h.

3) If needed, set the Spot Price Limit for your device via mobile app. (Settings ->Spot Price Limit)

Note! It is not recommended to add a Maximum Price Limit for Price Switch in normal use cases, as this might lead to a more expensive end result (in specific cases) and not heating at all. Without Max Price Limit, Price Switch will anyways select the least expensive hours of the day for heating.

Operating modes

Themo Price Switch has three operating modes that the user can choose from:

1) ON (relay always ON)
2) OFF (relay always OFF)
3 Price Switch (relay ON/OFF depending on parameters set by the user and real-time electricity prices)

Note! ON and OFF modes are only available from software versions 4.1.55 onwards. In case you have an older version, please contact our customer support.

Physical buttons

Themo T700DIN has three physical buttons. In Price Switch mode, only the button in the middle (Mode) can be used. The two buttons on the left and right are de-activated.

The mode button can be used to complete three different tasks:

1) Switch between the three operating modes (ON, OFF and Price Switch)
2) Disable Child Lock (Hold button down for 12 seconds)
3) Factory reset the device (Go into OFF mode, and then hold the button down for 15 seconds until the screen says ''RESET'')

Note! You can not enable Child Lock with the physical buttons. This has to be done via the mobile app.


The different symbols that you may see on the device screen are explained here.

''PRICE SWITCH'': The device is in Price Switch mode, and is controlling the relay according to the parameters set by the user and hourly electrical prices.

''ON'': The device is in ALWAYS ON mode, and the relay to the boiler is always closed (=constant heating)

''OFF'': The device is in ALWAYS OFF mode, and the relay to the boiler is always open (=no heating)

Lock symbol: Child Lock is enabled.

Letter/paper symbol: The device has received it's smart schedule from the cloud and it using it to heat the boiler.

Lightning symbol: The relay to the boiler is closed.

Wifi symbol: The device has a working Wifi contact.

Technical Specifications

For Technical Specifications, please refer to te attached ''Themo T700DIN Technical Specifications ENG'' document.


As Themo T700DIN does not take into account temperature data in Price Switch mode, it is extremely important that you do NOT use it for direct floor heating if the floor heating does not have a separate thermostat controlling the heating. When used incorrectly, the device may lead to overheating and a fire hazard!


1. ''My boiler has a heater element with over 3000W. Can I still use Price Switch and how?''

- Yes. Price Switch can be used to control all types of heating systems. We recommend installing Price Switch directly to the power supply of the heating system only when the maximum load of the heating system is below 3000W. For bigger loads than 3000W, a contactor should be used to control the power supply of the heating system. For contactor type recommendation, please see here

2. ''I have multiple heaters on my boiler. Can I control them all with Price Switch, and how should I do the installation? What should I do if the total power of the system is over 3000W?''

-Yes, you can install multiple heaters behind Themo Price Switch. However, it is mandatory that all heating systems have their own thermostat as Themo does not follow the heaters safety temperatures in Price Switch mode. To control multiple heaters with one Price Switch, a contactor should be used in a setup where Themo Price Switch sends control signals to the contactor which in turn turns all the heaters ON/OFF simultaneously.

3. ''If in the future there is a software update that allows me to follow the consumption of Price Switch, how should I do the installation?''

-Themo DIN thermostat can monitor electricity consumption, but not yet when it is in Price Switch mode. Our team is working on making a software update so that energy consumption could also be monitored in Price Switch mode (right now only the ON/OFF status of the relay is monitored).

However, this consumption monitoring can only be used if the heating systems power supply goes through Themo. If, for example, a contactor is used and the power supply goes only through the contactor, then it is not possible for Themo to measure power consumption.

4. ''What happens, if Price Switch loses power or I switch it off deliberately?''

-When Price Switch loses it's connection to the internet for more than 24 hours, it will go into ON mode (relay always ON). If the device completely loses electricat power, the relay will stay open and there will be no heating at all.

5. ''How should the Jumper part be connected?''

-The Jumper cable is used if the user needs to control a 230V load for the heating system/contactor. In such a setup, the jumper cable is connected into the two middle slots on the LOAD side of the connectors. This connects the mains L 230V with the relay output L Load. If Price Switch is used to control a 24V system, then there is no need to use the jumper cable. In such a case the 24V operating cable should be inserted into the relay connector slot (second one from the left), thus providing a 24V output from L Load.

See also: Recommended contactor for Themo T700DIN

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