All modern boilers are ‘modulating’, which means they can adjust their output up and down to meet the heat requirement. This saves gas and reduces fuel bills. However they can only reach their maximum efficiency when paired with compensation control that speaks the same language as the boiler. In order to fit a compatible compensation control you must either:
1) Fit the boiler manufacturer’s own compensation control, or
2) Fit a boiler and control that both use the OpenTherm language.Opentherm is a language developed by Honeywell that boiler and control manufacturers can adopted in order to make their products compatible. For more see our Guide to Opentherm boilers and controls
There are few types of types of modulation control: load compensation, weather compensation and combined load and weather compensation controls. The combined load and weather compensation units are the most efficient and deliver the most stable room temperatures. To review all load and weather compensation controls by product, see our Guide to the best smart controls.