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  • Writer's pictureDaniel Jackson

What is OpenTherm technology?

Have you seen/heard about OpenTherm but not quite sure what it means?

Here is a quick rundown of what it means and how it’ll affect your heating system.

OpenTherm is actually a communication protocol that talks/operates between the home thermostat and the boiler. Not every boiler and thermostat has this technology. If you have an older boiler and thermostat it is more likely that it will not contain OpenTherm technology. You can find out if your boiler and thermostat are OpenTherm compatible with the manufacturer’s instructions or ask your heating engineer.

What is the difference between an OpenTherm and a standard thermostat?

A standard thermostat operates in a very simple manner, it is either off or on. When a standard thermostat calls for heat it turns the boiler on and the boiler will operate at its set temperature until the demand for heat at the standard thermostat has been achieved. This means that the temperature of the room can overshoot the desired room temperature. The standard thermostat will wait until the room temperature drops, when it does it’ll tell the boiler to come back on to it set temperature and the cycle continues. This is quite inefficient for the boiler as its either burning fuel at max or nothing at all.

An OpenTherm thermostat is user-operated in the same way as a standard thermostat the difference is only skin deep. The way it is connected to the boiler is different, OpenTherm boilers have a dedicated OpenTherm wiring terminal to connect to. This allows the boiler to communicate to the OpenTherm thermostat. It’s this communication that allows the boiler to modulate the amount of fuel the boiler uses. So instead of the boiler cycling on/off, the OpenTherm protocol tells the boiler to use less fuel the closer the desired temperature becomes. This helps save fuel because condensing boilers are more energy efficient at lower temperatures.

Picture: Example of the boiler working with and without OpenTherm

What are the main benefits of OpenTherm:

  • Very simple installation

  • Helps the efficiency of your boiler/heating system

  • Helps to decrease “On/Off” wear and tear

Our favourite OpenTherm thermostats are:

Basic: Wireless EPH CombiPack4

Smart: Nest

For more information on OpenTherm thermostats and boilers, feel free to contact us at DPJ Plumbing, Heating and Gas on 07971693134, 01889597377 or on our contact page.

OpenTherm Website:

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