Adjust your combi boiler flow temperature for increased efficiency

Adjusting a combi boiler is much easier as you can simply set the lowest boiler flow temperature that keeps the home warm. Flow temperature is the temperature of the water running through your radiators, pipework and system.

There are advanced design calculations that can help determine the flow temperature, however for this technique we set the boiler flow temperature to 55 degrees, which virtually guarantees condensing efficiency savings.

From this 55 degree flow temperature set-point, if you are not getting the home warm, you can increase by 1-2 degrees at a time, let the system run for a day and then repeat as necessary.

You may find that 55 degrees set-point works for most of the year except very cold days. For these colder winter situations, you find the temperature that works for the extremely cold days and use 55 degrees set-point for the remainder.

A small amount of trial and error is necessary without heatloss calculations or heatloss testing, for determining the flow temp. See below videos below showing you how to adjust the flow temperature. There is also a calculator for showing approx condensing boiler savings *See disclaimer below.