What Temperature Should I Set My Boiler To?

Most people have their boiler set too high, which wastes gas and money. Here is how to set it properly for both efficiency and comfort.

Two temperatures to understand

Your heating system has two separate temperature controls and they do different things:

The boiler flow temperature

This is the temperature of the water leaving the boiler and going to your radiators. It is set on the boiler itself, usually with a dial or on the digital display. Most people have this cranked up to maximum (around 75 to 80°C), but that is almost certainly too high.

For a modern condensing boiler, the ideal flow temperature for radiators is 50 to 60°C. At lower flow temperatures, your boiler runs in condensing mode, which is how it achieves its advertised 90%+ efficiency. Set it to 70 or 80°C and it barely condenses at all, dropping efficiency significantly.

For hot water, set the temperature to 50 to 55°C. That is hot enough for comfortable showers and baths without scalding risk.

The room thermostat

This is the dial or digital controller on your wall (or your smart thermostat). It measures the air temperature in the room and tells the boiler when to fire and when to stop. Set this to your desired room temperature:

• Living rooms: 19 to 21°C
• Bedrooms: 16 to 18°C
• Bathrooms: 21 to 23°C

A common mistake is setting the thermostat to 25°C to "heat the room faster." That does not work. The boiler outputs the same amount of heat regardless of where the thermostat is set. All you are doing is telling it to keep running until the room hits 25°C, which wastes gas and makes the room uncomfortably warm.

The money saving sweet spot

Flow temperature at 55°C, room thermostat at 19 to 20°C. Turning your thermostat down by just 1°C can save around £80 per year on gas bills. That is not a typo. One degree, eighty pounds.

Need help with your boiler? Our Gas Safe registered engineers cover the North East. Get in touch today or call 0191 540 2051.

Knowing what temperature to set on the boiler flow and on the room thermostat is one of the simplest ways to cut your heating bills this winter.