Load Compensation and Modulating Controls
Load compensation varies the boiler output based on how far the room is from its target rather than on the outside temperature.
Load compensation varies the boiler output based on how far the room is from its target rather than on the outside temperature. It needs no external sensor, which makes it the easier retrofit of the two compensation methods.
How it behaves
As the room approaches temperature the boiler throttles back instead of switching off, holding a steady, low flow temperature.
Short cycling is the enemy
A boiler that fires hard, hits target, stops, then repeats wears components and wastes fuel. Modulation is what stops that.
Protocol matters
OpenTherm or a manufacturer's own bus lets the stat and boiler negotiate. A simple on/off stat cannot do this however smart the app looks.
If you are choosing controls alongside a new appliance, our boiler replacement page explains the survey and installation decisions.
Questions we get asked
Is load compensation as good as weather compensation?
It is close in practice and much easier to retrofit. Some systems run both together.
Do I need to change my boiler?
Not necessarily. Many boilers already installed locally support modulating control that has never been wired up.
Will it make the house slower to warm?
Slightly gentler, yes, but with better temperature stability once it gets there.
What is load compensation?
Load compensation is a control method that uses the difference between the measured indoor temperature and the temperature you have set to adjust the boiler's heating demand. As the room approaches its target, a compatible controller asks for less heat rather than relying only on full on/off calls.
Can a new boiler use load compensation?
It can if the chosen boiler and controller support a compatible modulating connection. Check the exact appliance, control and wiring arrangement before buying; an app-controlled thermostat is not automatically load-compensating. A replacement installation is an opportunity to choose and commission the controls together.
What is the difference between load compensation and weather compensation?
Load compensation responds to indoor temperature and demand. Weather compensation uses an outdoor sensor to adjust heating flow temperature as the weather changes. They use different information, and some compatible boiler and control arrangements can combine both approaches.