Thermostats – Heating your home

Thermostats – Heating your home

How do I use my thermostat controls?

There are lots of different types of heating controls, so for specific advice, it’s good to check with your installer or read the manufacturer’s manual.

If you don’t have a copy of the manual handy, these can often be found online by searching for the manufacturer’s name.

We’ve listed some common functions below.


A timer or programmer allows you to control when your heating and hot water comes on and when it goes off.

This is useful because it means you can programme your central heating to fit around the way your home is used.

If you’re not at home or don’t require heating at night, then you can programme the heating system to switch off during these times.

Older programmers are simple timers that only operate once a day, but modern programmers offer options to control multiple on and off periods.

More sophisticated programmers now exist that are usually referred to as smart heating controls, which could offer more convenience and energy savings.

Depending on how your central heating system was installed, programmers are either:

  • Single channel – for combi boilers. This only controls central heating as hot water is provided on demand.
  • Two channel – for system or regular boilers, controlling heating in a single zone and hot water, or combi boilers controlling two separate heating zones (eg upstairs / downstairs).
  • Three channel – for system or regular boilers, controlling hot water and two separate heating zones.

How to set your programmer to save energy

The programme you set will be unique to your heating needs, but here are a few tips if you’re looking to save energy.

  1. Plan ahead

The less often you have the heating and hot water on, the more money you will save.

Think carefully about when you need the heating, and any periods in the day when you don’t need it – for example, if everyone in the home is out at work or school, the heating can be off.

Some programmers allow you to set different programmes for different days, so you can match it to your schedule.

  1. Include warm-up and cool-down times in your programme

It takes time for a house to heat up after the heating switches on and will take a while to cool down after the heating is switched off.

Generally, the average house will take about 30 minutes to heat up or cool down, but every home is different.

To find out your home’s ‘warm-up’ and ‘cool-down’ times, you could choose a cold evening and time how long it takes for your house to warm up to a comfortable temperature – this is the warm-up time.

Then turn the heating off completely and time how long it takes for the house to start to get uncomfortably cold – this is the cool-down time.

You can now set your programmer, including the warm-up and cool-down time.

For example, you can make sure that the heating goes on with a warm-up time before you wake up and turns off before you leave the house.

If you insulate your home, it will warm up faster and cool down more slowly, saving you money on heating.

  1. Don’t forget hot water

Set your water to heat up only when you need it.

If your hot water cylinder or tank is well insulated, you may even find that the hot water supply in the morning stays hot enough to use in the evenings.


These prevent your home from getting warmer than necessary.

They turn the heating on until the room reaches the temperature you have set, and then off until the temperature drops.

Room thermostats need a free flow of air to sense the temperature, so they should not be blocked by curtains or furniture, or placed near heat sources that could give them false readings.

Your room thermostat should be set to the lowest comfortable temperature, which for most is between 18°C and 21°C.

If you only have a single room thermostat for the whole house, for every degree you increase the temperature, it will increase the heating bill by about 10%.

You don’t need to turn your thermostat up when it is colder outside; the house will heat up to the set temperature regardless.

It may take a little longer on colder days, so you might want to set your heating to come on earlier in the winter.

Programmable room thermotstats

A programmable room thermostat combines time and temperature controls in a single unit and allows you to set different temperatures for different times of the day.

Some heating systems may use two programmable thermostats (upstairs and downstairs) rather than a single programmer for the whole house.

Thermostat radiator valves

Thermostatic radiator valves (TRVs) do not control the boiler; they control the flow of hot water through the radiator they are fitted to.

They work by sensing the air temperature around them.

If the room is warmer than the setting on the TRV, the valve will close a little, reducing the volume of hot water flowing into the radiator.

If the room temperature is lower than the TRV setting, the valve opens, increasing the flow of hot water into the radiator.

A radiator cover can prevent the TRV getting an accurate temperature reading.

Warm air, heated by the radiator, can get trapped under the cover, and the TRV can read this thinking the room is warmer than it is.

We do not recommend having radiator covers, if possible.

TRVs can be adjusted to different settings by twisting them clockwise or anti-clockwise.

They are usually marked with a scale from 0 – 6, where zero (0) is off and six (6) is fully open.

Aim for the lowest setting that keeps the room to your desired temperature.

A lower setting reduces the volume of hot water, using less energy and saving you money.If you’re not using a room, TRVs can also be used to either turn the radiator off completely or maintain a minimum temperature to keep the room just warm enough to prevent damp.


Dave Stroud
Author: Dave Stroud