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Simple Boiler Adjustments to Lower Your Heating Bill

Author: Samuel Beckingham
Updated: Oct 07, 2022
3 minutes read

There is a way to use your boiler more efficiently in order to reduce the expense on heating this winter. While you can save money by turning down your thermostat, you can’t keep doing that below comfort levels. However, by adjusting the flow temperature, you can effectively stop your boiler working so hard.

Combi boilers heat water on demand, removing the need for a separate water storage tank or hot water cylinder. They are able to work more efficiently than their system boiler counterparts and allow you to adjust the flow temperature. This is the temperature of the water that leaves the boiler as it travels to your central heating.

Flow temperature is separate to the thermostat setting. It’s the temperature of the water that leaves your boiler to travel to your radiators. The boiler pumps water up to 80ºC around your home until the air around the thermostat reaches its selected setting. By adjusting this, you can effectively cut your heating bill without compromising comfort.

There are, unfortunately, different limits if you have a system boiler with a hot water cylinder. Stored water needs to be heated to at least 60ºC to kill harmful bacteria, such as Legionaella. As combi boilers heat mains water on demand, there is very low risk of this being an issue. System boilers don’t tend to have an option to adjust the flow temperature, so this only works with combi boilers.

Combination boilers are so efficient that they’re able to operate with much lower flow temperatures of 50-70ºC, or even lower. This reduces the amount of energy used during operation, which is an immediate saving as you’re not using as much fuel, be it gas, electricity or oil.

Your combi boiler should also let you choose how hot the water supplied to your taps is. Adjusting both of these settings is a good way of making use of your boiler’s efficiency and reducing your heating bill. It’s also worth noting that the temperature selected won’t be the temperature of the water that comes out the taps, as some heat is lost in the process.

While actual savings vary by home and heating system, a study by the Heating and Hotwater Industry Council shows that you can save 6-8% on your gas bills by lowering the flow temperature to 50ºC. Knocking off 30ºC from how hard your boiler works equates to real world savings. The Heating Hub went one further by saying you can save an additional 5-10% if you turn off the pre-heat setting on a Worcester, Vaillant or Ideal combi boiler.

Reducing flow temperatures naturally reduces the surface temperature of your radiators, meaning it will take longer for your rooms to get up to the desired temperature. This will be a good option for you if your home heats up quickly or often overheats, but isn’t so good for people with poorly insulated homes or with older and smaller radiators. The system will struggle with the low temperatures and you’ll then be stuck with a system that can’t heat your home.

It is advisable to consult a heating engineer before making these changes, as they’ll be able to suggest the best settings for your home in relation to your heating system.