Adjust your system regular boiler flow temperature for increased efficiency

Adjusting the flow temperature for a system boiler or regular boiler is different to a combi boiler. When you have a hot water cylinder, normally you set your cylinder stat 60 °C, to prevent legionella formation. When you set to these temps, the boiler flow temp must be higher by at least 5 degrees, in order to heat the cylinder and satisfy the cylinder stat, otherwise the boiler would not stop firing until the timer turns it off and the cylinder would never reach it’s intended temperature.

It is therefore suggested to change to a flow temp of 65 °C at the boiler in order to maintain a minimum difference of of 5°C . If the difference is smaller, the time taken to reheat the water is longer and may not satisfy hot water requirements. A higher flow temp of 70°C would mean that the hot water would warm up faster, but you would lose some efficiency.

If you have advance controls these can automatically have different flow temperatures for the hot water cylinder and heating. The usual advanced setup is called priority domestic hot water setup (PDHW). This is outside the scope for this article. Please contact us for more information on this, alternatively we will create an article on PDHW at a later date. Now select your boiler below to see how to adjust the flow temperature.