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Save energy by turning down your room thermostat
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Turning down your room thermostat could help reduce your energy bills
Turning down your room thermostats can help reduce your energy bills

Ensuring home heating systems are working as efficiently as possible is more important than ever, not only to help systems operate as sustainably as possible but also to help households to keep on top of their energy costs. Neil Sawers, Grant UK’s Commercial Technical Manager, shares some advice in this blog to help homeowners understand best practice when it comes to heating their homes.

The current costs of energy are of great concern to consumers at the moment and there are lots of outlets sharing advice about how homeowners can keep in control of their heating and energy bills. It is incredibly important that you fully understand how your heating system works because some so-called energy saving measures can in fact have a negative impact on the real running costs of your heating and hot water system. With boilers, there is a lot of terminology that can get confusing so let’s look at what thermostats are and which ones should be let be, and which ones can be adjusted.

What are thermostats?
Put simply, a thermostat is a device that can alter the temperature of the appliance or system it controls. In a typical central heating system, whether that be using a gas or oil boiler, there will be two types of thermostat – the one on the boiler itself and the thermostats placed throughout the house. The boiler’s thermostat controls the flow temperature of the boiler (essentially its output), a temperature which is specifically set during installation to ensure that the boiler can fulfil the household’s heating requirements. Meanwhile, room thermostats monitor the temperatures within specific rooms or zones and these feed into the heating system, triggering it to fire up (if rooms are too cold) or pausing the fire-up process (if rooms are up to temperature).

In summary, the boiler’s thermostat should only ever be touched or altered by your heating engineer whereas the room thermostats within your home, can be changed by you to set your desired room temperatures.

Use room thermostats to adjust your room temperatures
In the average home, there is usually one room thermostat downstairs and one room thermostat upstairs (some homes may have more if they want to set room specific temperatures within the same level of a house). Depending on the type of room thermostat, it will monitor the temperature of the room or zone and when the temperature falls below the desired set temperature for that space, it will send a signal to the boiler to fire up and heat the system to warm up the area.

Every home is different but typically, the downstairs of a property will have its room thermostat(s) set to between 20-22ºC whereas the upstairs area will be set to between 18-20ºC. Furthermore, most room thermostats nowadays give consumers the option to select their desired temperatures throughout the day, for example, being warmer between the hours of 6-9am and 5-10pm and then cooler during the periods of the day when the house is not occupied or when the household is asleep.

One way homeowners can reduce the demand on their heating system is to turn down their room thermostat(s) by one or two degrees. You could also look at the times of the day that you want your heating to be on, maybe reducing the time frame when you set your room thermostats to the higher, occupied temperatures. However, it is important that reducing your room temperatures, via a room thermostat to make for slightly colder rooms, does not compromise the health and well-being of yourself or those you live with – always maintain a temperature which is comfortable and safe.

Do not change your boiler’s thermostat
If we now turn to the boiler’s thermostat, this is where we will get more technical. When your boiler and heating system was first installed, the heat emitters (such as your radiators) should have been sized for the room in which they are located and therefore designed to operate at a particular flow temperature. By reducing the flow temperature on the boiler (via the boiler’s thermostat), the net effect will be to reduce the output of the heat emitter. So, when the weather gets colder, more heat will be required to the heat the room than the radiator can provide in these conditions.

Reducing the boiler’s thermostat can therefore create two potential problems. Firstly, the room or zone will not be able to reach the designed temperature (21ºC for example). Secondly, because the room temperature will never be satisfied (in this example, it will never reach 21ºC), the room thermostat will never send the signal to switch off the boiler off. This will result in the boiler working more and therefore higher, not lower, energy bills.

It is also worth noting that by turning down the boiler’s flow temperature (via the boiler’s thermostat), this may prevent the hot water cylinder from reaching its pre-set water temperature which again will mean that the boiler is running for longer, thus using more energy.

Leave your cylinder’s thermostat alone too
Another thermostat which we recommend that householders avoid tampering with is the cylinder thermostat. Unless you have a combi (or combination) boiler, you will likely have a hot water cylinder in your home. A cylinder’s maximum temperature should never exceed 60ºC, however, if the cylinder’s thermostat is reduced to below 55ºC, this could create conditions where legionella bacteria can develop. While most heat pump installations have a sanitisation regime in place to regularly sanitise the stored water (by raising the water temperature to 60ºC and holding at this temperature for one hour every week), non-combi boiler installations do not have this regime in place. Therefore, turning down the cylinder thermostat can have significant implications, especially for the vulnerable, and should be avoided (when the boiler is not a combi model).

In conclusion then, what can you do? Here are my top three pieces of advice:

  1. Review your room temperatures and, if safe to do so, maybe consider lowering your room temperatures via your room thermostats by a degree or maybe two.
  2. Leave you boiler thermostat and, if applicable, cylinder thermostat as they are – if you are keen to adjust either of these settings, please seek the advice of a competent heating engineer.
  3. Start looking at the ways you can reduce the heat loss from your home – this could be in the form of improved insulation, not leaving doors or windows open unnecessarily, and opting for thicker blinds or curtains. If you are interested in reading more about home insulation and energy efficiency measures, please visit one of our other blogs.
Neil Sawers
Commercial Technical Manager at Grant UK