Running your heating for longer, rather than short bursts
When you start your heating system it has to do a lot of work. Not just to heat up the building, but also to pump water through the system and get everything started.
The impact of this is that it will use a lot more gas in the first hour of operation than it does to keep the house warm once a comfortable temperature has been reached.
The graph below shows the gas consumption by a heating boiler every half hour for a full day. This is from a test carried out by BEAMA with the heating set to come on in the morning and then again in the afternoon/evening.
The big peak at the start of each heating period shows how much extra gas the boiler uses when getting the house up to a comfortable temperature. In fact, the numbers show that it uses 2-3 times more gas in the first hour than in every other hour that it operates.
What does this mean for how you use your heating system?
With the cost of gas so high, there is an obvious tendency for people to ‘ration’ the amount of heat that they use and, for example, to just put it on for an hour to “warm the house through” and then put it on again when the house has cooled down.
This is probably not the best thing to do, so we’ve used the test data to compare ways you might choose to reduce the amount of heat you use.
Based on the afternoon/evening period shown above we’ve looked at three approaches to running the heating system:
Option 1 – Heating comes on and 3.30pm and off at 11pm.
This would be the expected way of heating for the time when a family might be relacing in the living room and the graph shows the living room temperature being maintained at around 21 degrees C once the house has warmed up.
Average temperature – 21.1 degrees C
Gas used by the boiler – 44 kWh
Estimated cost of gas for this period - £4.53
Option 2 – Heating on for 1 hour at 3.30pm and I hour at 9pm.
As mentioned above, this would be the approach of putting the heating on for an hour to “warm the house through” then letting it cool down again. The graph shows that the heating doesn’t have time to get the house above 20 degrees C.
Average temperature – 16.5 degrees C
Gas used by the boiler – 29 kWh
Estimated cost of gas for this period - £2.99
This approach does not successfully keep the house warm and is not as economical as you might think as the heating system is having to warm up the house from cold each time it comes on.
Option 3 – Heating on for 4 hours, from 3.30pm to 7.30pm.
A better alternative to option 2 would be to run the system in a single block of time so that it gets the house up to temperature and then keeps it there for a period – utilising the lower gas consumption after the house is warm.
Average temperature – 18.6 degrees C
Gas used by the boiler – 30 kWh
Estimated cost of gas for this period - £3.09
This provides a longer period of warmth and a higher average temperature than option 2 for around the same gas usage. While it’s still not ideal that the living room temperature has fully declined by 11pm, this could be avoided with a slightly later starting time, or an extended running period.
The options shown above are only there to illustrate the point that running your heating system for just an hour at a time may seem economical but is not very effective at keeping you warm. Making do with low temperatures is never a good option, and definitely to be avoided if there are any vulnerable people in the home.
The general principle is that, if you do want to economise on using your heating, longer periods with the heating operating are the way to go.
(Technical note: While option 1 is based on an actual test, options 2 and 3 have been taken from analysis of the data from that test. How this works in an individual house will depend on the boiler type, room thermostat type, and levels of insulation. However, based on analysis of all the tests BEAMA have done on heating systems there is a high level of confidence that this principle applies with any high temperature system.)