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Why you should turn down your gas boiler
When gas boilers are installed, the fitter often sets the central heating water temperature to as high as 80 degrees. When the thermostat indicates your house is getting below the set temperature, your gas boiler will wake up and use loads of gas to send superhot water around your radiators, quickly warming your home to the required temperature. The system will then go to sleep and your house will cool down until the thermostat wakes it again, creating big swings in temperature.
There is a better way
Modern combi boilers have electronic controls that allow the temperature to be set with a simple control on the front.
This opens the way for a better, cheaper way of warming your home; producing water for central heating at 60 degrees or even lower. Your boiler must be active longer, heating your house more gradually. Your home's temperature should remain the same but with fewer swings in temperature. But it will use less gas because boilers are more efficient in generating warm water than water that is scalding hot.
It's important to note that we're not proposing that you change the temperature of your house. Your home should remain as cosy as before. We're talking about making a small adjustment to the front of your boiler.
As a side note, if you have children or elderly people who may fall against a radiator, cooler radiators are safer, too. There’s evidence that an even temperature is better for health too.
(Another side note is that modern combi boilers can set a different temperature for the hot water for taps. You can save a bit of money by reducing that, too.)
Innovation charity NESTA did a study where they found that turning the temperature of a gas boiler down from 80 degrees to 60 degrees could save 9% on an annual gas bill (If you want to read the technical study, it is here. Or watch this video from a guy who did a simple test. )
Our recommendation is slightly different from that of NESTA: we at HGS REACH recommend a step-by-step approach, turning the temperature down 5 degrees C and then waiting at least a week so you can be sure your home is still warm in every room. If it is still warm, turn it down by another degrees until you think you've gone too far, then bump it up again. A moderately insulated Suburb home may be warm with a flow temperature of 55 degrees.
You may also want to check your radiator valves, as some may not be fully open, and when turning your flow temperature down, you’ll want to take full advantage of your radiator size. Another benefit of this is that your central heating system is likely to last longer. Lower flow temperatures mean less corrosion in pipes, and less wear and tear on the boiler parts.
What buttons do I press?
This guide from NESTA shows the standard control panels for combi boilers and the buttons to press:
https://moneysavingboilerchallenge.com/
NESTA estimates more than 3 million UK households have reduced their flow temperature because of their campaign, saving 500,000 tonnes of CO2 and nearly £300 million in bills.
EXTRA TIP: Many combi boilers, including Worcester, Vaillant, or Ideal, have a function of "pre-heat", which keeps some water hot inside the boiler to reduce the time taken to deliver hot water to your taps. It's nice — but it can add 5% to 10% to gas bills, according to Which? It can be switched off using the control panel on the front of the boiler.
Now, some questions:
Q: What if most of my home is generally warm with a lower flow temperature, but one room is a bit cold?
An easy way to investigate why that room is cold is to borrow the HGS infrared camera. This will allow you to explore the room for draughts, faulty insulation, ill-fitting windows, blocked radiators, and other problems. Find out more here.
Q: What if I have a hot water tank?
If you have a hot water tank then you don't have a combi boiler and it's more complicated. You need guidance from your heating engineer here. Note that the central heating temperature needs to be at 60 degrees at least occasionally to avoid bacteria growing. (This isn't a risk for combi boilers.)
Q: How does this show my house is ready for a heat pump?
We at HGS REACH believe heat pumps are a fundamentally better way to heat homes than a gas boiler — they significantly reduce the CO2 emissions from a house (much more than, say, switching to an electric car).
But heat pumps are most efficient producing warm water at 50 or 55 degrees. If your home is toasty warm with the gas boiler set at these lower temperatures (or a bit higher), then this implies that little or no extra work will be required to replace your gas boiler with a heat pump.
Want to learn more about heat pumps? Watch the video of our seminar.
If you do decide to turn down your flow temperature, we’d love to hear about your experience. You can email us as reach@hgsra.uk
Article created:20th December 2024