Opentherm – how does it work?

Enjoy the best design and functions combined together.

How does it work?

Most boilers currently have a simple on/off control system, with a mechanical room thermostat and time clock which means that the boiler is switched on and off at intervals to either provide full heat power or no heat at all.

On the other hand, modulating control means the heating power is increased or reduced based on the actual output needed.

Boilers which are the actual “Slave” are controlled by the “Master” which is the OpenTherm Thermostat calculates exactly is need in the system every few seconds and sends information to the “Slave” to either increase, decrease or stay where it is.

So to put it in simple terms if you only require a small amount of heat to heat a particular part of the house the OpenTherm master control will tell the slave to run at minimum power or whatever power it calculated until it sees a change in the temperature and then continues to regulate the heat output as required, and if another zone comes on it will keep adjusting to suit the load to suit. So to get the best from OpernTherm a multi zone system such as EPH Controls or Honeywell Evohome is advised.

Underfloor heating

Underfloor wet heating is a very efficient form of heating the downstairs of a property and gives that extra feeling of warmth within the building and eliminates cold spots.

However, it does behave differently than traditional radiator systems as you have a longer gradual heat up time. Once its warmed up to the desired level it just needs topping up to maintain the heat.

The Sapphire Fully Modulating Boiler on OpenTherm multi zone controls really comes into its own and works perfectly with underfloor heating. This is thanks to the stainless steel construction that eliminates low return temperature corrosion, that is associated with other boilers.

With fuzzy logic that is incorporated into the system the hub will self-learn and calculate the heat times for each area of the property.

Underfloor zones have a wireless thermostat per area that again feeds back to the hub and calculates the heat load accordingly. It then sends the correct message to the boiler slave control and adjusts the output of the boiler correctly. This is called load compensation.  

OpenTherm Advantages

OpenTherm controls have many benefits, from money saving thanks to lower fuel consumption to their compatibility with evolving smart controls

Modulating Control

Modulating Oil Boilers have previously been rejected by the oil industry because it was believed that they had no advantage over standard on/off versions.

Modulating Control means the heating power is increased or reduced based on the actual output needed.

Multi Zones

To get the best out of OpenTherm technology, a multi zone system such as  Honeywell Evohome is advised.