08 Oct 2018

5 Things You Didn’t Know About OpenTherm

For many seasoned installers, ‘OpenTherm’ is a term that is becoming a familiar part of the installation language.

That is because OpenTherm devices are increasingly seen as an important part of a modern heating system. Here are our top five tips on the basics of OpenTherm and heating controls.

OpenTherm is the name given to a form of communication between modulating (condensing) boilers and room thermostats, setting the rules as to how the these communicate with each other.

How does it work?

The standard way to control a heating system is to switch the boiler on and off at intervals with on/off controls. OpenTherm provides more precise control on the boiler by adjusting the flow temperature. This allows the amount of heat provided by the boiler to be controlled to match the varying demand signal.

By reducing the flow temperature to a minimum as it leaves the boiler, OpenTherm modulation helps the boiler efficiency by running at lower flow temperatures for longer periods. This ensures more of the heat exchanger is at condensing temperatures.

So, what benefits can installers and their customers expect to gain from using this technology?

1. Efficiency boost

As we’ve already touched upon, the big advantage of OpenTherm is energy efficiency, which - in turn - helps to lower fuel bills. OpenTherm not only maintains the correct room temperature set point but also helps the boiler's efficiency by running at lower flow temperatures for longer periods. This ensures the boiler stays condensing for longer periods of time.

2. Increased boiler lifespan

Because boilers are kept in condensing ‘mode’ for longer periods, the impact on the appliance is less than if it is constantly firing up and shutting down. This means that wear and tear is reduced, with the boiler able to operate at optimal performance levels for longer.

3. Essential function

The essential function that every OpenTherm controller must provide is the communication of the control set point (heat requirement) to the heating appliance. This requirement is calculated by the controller on the basis of the difference between the set temperature and the desired one, or another form of control such as outside temperature control

4. Enhanced boiler diagnostics

Some OpenTherm heating controls provide boiler status and a range of fault codes directly on the screen of the thermostat – providing the installer with additional points of feedback.

5. Future ready

OpenTherm opens the door to extra functions and an advanced level of thermostat control. For example, the ability for remote control of the boiler brings future advantages in terms of the monitoring and efficiency of the heating system.

The OpenTherm logo on a product provides a visual confirmation that the heating control will work with a boiler displaying a similar mark. The OpenTherm Association provides a wealth of information about working with OpenTherm appliances or for information on Honeywell OpenTherm heating controls visit www.honeywelluk.com

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