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    Boiler controls explained: How do they work?

    If you aren’t super knowledgeable about boilers (which is understandable as most homeowners won’t be) you might not be fully sure how all the controls for your system work. With all the modern technological advancements in recent years too, it might feel like your central heating and hot water system is complex and difficult to use, but it’s actually pretty straightforward. In this guide we’ll be explaining how the key controls on your boiler work. So, you can be sure that you’re using it effectively and maximising its efficiency and capabilities as much as possible.

    Setting up your boiler controls

    Your boiler controls are essential for managing your heating and water supply. It might not seem like it, but they can make a big difference to your overall efficiency and energy bills. The Energy Saving Trust has even stated that making minor changes like installing smart thermostats and thermostatic radiator valves (TRVs), could save you anywhere between £75 and £155 per year. Not only that but reducing the temperature of your heating by only 1C can save you roughly £80. So, having your controls set up correctly and fully understanding their workings is going to be hugely beneficial to you.

    To set up your controls properly you first need to determine what type you already have, or which ones you want to have installed. The majority of boiler systems will come with a room thermostat, and as mentioned above you can benefit from your radiators featuring TRVs. The exact right way to use your boiler controls can depend on the type and model of your unit. If you need specific details and direction on how to use your controls, be sure to check your boiler manual. The four controls we will be covering below are:

    • Room thermostat
    • Boiler thermostat
    • Boiler timer control
    • Thermostatic radiator valves

    Room thermostat

    As the name suggests, the purpose of a room thermostat is to read the temperature of a room and feed that information back to the boiler system. If the room drops below the temperature, you set it to, the thermostat will trigger the boiler to turn on. When the room is heated up to the set temperature, the heating system will switch off.

    Your room thermostat should be located on a wall in your home that is away from your boiler and radiators, in a central area that isn’t exposed to direct sunlight. This will allow the sensor to read the temperature of the room accurately. Analogue and digital are the two types of thermostats you can get with the latter being more popular due to their modernity and advanced features that improve their accuracy. However, if you’d prefer a standard display and a simple option then an analogue thermostat will be suitable and effective.

    A room thermostat is an important control as it can help you become more energy efficient in your home. Without one, your boiler wouldn’t know when to stop sending hot water through your radiators and your house would get very hot.

    It is recommended that you set your daytime temperature at roughly 20C and your night temperature between 16C and 19C if you want to be more efficient and save money on your bills.

    Boiler thermostat

    Your boiler thermostat allows you to control the temperature of your central heating and hot water. Therefore, you have the ability to set the temperature your specific preferences. This is especially useful for different seasons as you will want your heating on in the winter and will leave it turned off throughout the summer. In terms of your hot water, the recommended temperature for it to be set at is roughly 60C and 75C for your radiators.

    It is important to remember that if the water temperature is set too low, it can create favourable conditions for bacteria to grow. Therefore, the temperature should be set to no lower than 60C. The thermostat of the boiler is connected to the timer control, which will be discussed later in the guide. This connection allows you to set the boiler to come on at certain times of the day with the preferred temperature.

    Boiler timer control

    Every boiler will come with a timer that allows you to set what time during the day you want your boiler to come on and how long it should be on for. Most homeowners will programme the boiler to be on in the morning, turn off during the day while they’re at work then come on for a few hours when they get back or are just about to get back in the evening.

    More modern timers even have a seven-day function, so you can set different times for your boiler during the week compared to weekends when you’ll be in the house more. Also, certain types of boilers, particularly combi systems will have a mechanical timer. It comes in the form of a round dial with a 24 hour clock on it. Each hour is split into 15 minute slots, so you have the option to put your boiler on for some extra heat if you need it at a time that doesn’t fall in your programmed hours.

    Thermostatic radiator valves (TRVs)

    These valves allow you to control the temperature in each individual room of your home via the radiators. They come in the form of nozzles at the bottom of the radiators and feature numbers 1-5. When the TRVs are set to 5 the radiators will be at their hottest as their will be more flow of hot water going through them.

    You shouldn’t have a TRV on a radiator that’s in the same room as your thermostat. This is because a tampered radiator will lead to inaccurate temperature readings on the thermostat and send the entire system off balance.

    It is typically recommended that your TRVs are set to 3, which is around 20C. Except for bedroom radiators which should be a bit cooler at number 2.


    We hope this guide has given you a clearer insight into the key controls on your boiler system. If you have any problems with your heating controls or any of your central heating parts NBS can help. We specialise in providing high quality, affordable new and refurbished UK boiler parts for our customers. Explore our online shop today to find the right boiler spares for your system.