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Thermostatic Valve

A thermostatic valve is a component that's installed on a radiator and used to regulate the temperature of a room. Together with a radiator valve, a thermostatic valve therefore forms part of a radiator's tap, with the terms thermostatic tap and thermostatic valve often being used interchangeably. Attached to a radiator, a thermostatic valve is used to regulate the temperature in a room by adjusting the flow of water in a radiator, usually by means of a graduated wheel or knob in the case of the most basic models.

Unlike an atmosphere thermostat, instead of controlling the boiler a thermostatic valve allows independent regulation of the temperature room by room. These valves can therefore replace or supplement the use of a thermostat in the home to fine-tune the adjustment of the ambient temperature in each room.

How does a thermostatic valve work?

Visually, a standard thermostatic valve looks like a tap with a graduated adjustment knob. It is made up of a thermosensitive radiator valve that measures the ambient temperature using a temperature sensor (also called a thermostatic bulb) and the body of the tap, which contains the mechanism for regulating the heating according to the ambient temperature measured and the chosen setting.

The way a thermostatic valve works is simple. By turning the knob to choose a position, you can select the setpoint temperature you want to achieve in the room that has a radiator fitted with a valve. The temperature sensor contains a liquid, gas or gel that contracts and expands under the effect of the ambient temperature. Depending on whether the thermostatic bulb is more or less expanded, a mechanical counter spring adjusts the opening of the regulating valve and therefore the flow of water into the radiator.

When the ambient temperature falls, the sensor contracts and the mechanism allows a higher flow of water into the radiator to reheat the room. Conversely, if the ambient temperature rises (due to the sun shining in through a window for example), the thermostatic bulb expands and the flow of water is reduced.

The tap is usually marked from 1 to 5 and also has a frost protection position marked with the symbol *. Some taps are graduated in degrees, although this is rarer. Once regulated, the purpose of thermostatic valves is to maintain a consistent temperature in the rooms where they are fitted. Discover all our products

The different types of thermostatic valve

A wide range of thermostatic valves are available on the market. Both in DIY stores and online you'll find all types of products at all kinds of prices (from €20 to €120). There are freely adjustable, pre-regulated and blocked products, valves with integrated or remote adjustment, integrated or separate heat sensors, programmable thermostatic valves, etc. All of these products have various advantages and your choice will depend on your budget, as well as where you're installing the valve and the constraints of your home.

The thermostatic radiator valves currently available include three main categories of products: manual thermostatic valves, electronic thermostatic valves and smart thermostatic valves.
  • Manual thermostatic valves
Also called mechanical thermostatic valves, manual valves are the cheapest and most basic heating regulation product. They have a knob marked from 1 to 5 to set a higher or lower setpoint temperature depending on the type of room being heated and whether it is occupied. Although a manual radiator valve is a fairly simple product, it may suffice for a small space.
  • Electronic thermostatic valves

    An electronic thermostatic valve, also called a programmable electronic valve, is more expensive but is also more sophisticated than a manual valve. It has a digital display and the temperature reached using the radiator is more accurate than using a simple graduated wheel system. The temperature can very often be adjusted to the nearest half-degree.

    More importantly, the programming feature allows you to define a heating programme that's suited to your lifestyle: this means that the temperature is automatically lowered at night or when you're not at home during the day, when you don't need to maintain optimal thermal comfort in a room. Some sophisticated types of programmable thermostatic valve even allow you to program several schedules, for example for during the week and at the weekend. Electronic thermostatic valves are therefore very practical, provided your schedule is relatively consistent.
  • Smart thermostatic valves
Even more advanced, smart thermostatic valves provide a level of accuracy at least equivalent to that of electronic thermostatic valves, to the nearest half-degree. They also offer a range of features that justifies the higher cost. As well as being able to manually adjust the temperature by turning the tap on the radiator, you can control your valve remotely on your smartphone or tablet using a management app.

A smart thermostatic radiator valve allows you to create different heating schedules according to your habits. The Netatmo smart thermostatic valve has several modes for all different types of situations: night mode, comfort mode, comfort+ mode, which raises the temperature by a few degrees in the bathroom, and lastly eco mode, which limits the temperature in a room, and therefore your energy consumption, while you're not at home.

Most importantly, thanks to the remote adjustment feature you can adapt the temperature in each room in your home that's fitted with a smart thermostatic valve, even if something unexpected comes up or your schedule changes. Maybe you're getting home later than expected or extending your holiday. Just alter the setpoint temperature on your thermostatic valve using your smartphone to avoid having the heating on unnecessarily while you're away! Netatmo thermostatic valves even work with the leading voice assistants: Alexa, Siri and the Google assistant.

Lastly, smart thermostatic valves are independent. They continuously analyse the environment of the room they're in and adjust the heating accordingly. They take into account the insulation of the room, how much sunshine comes into the room and even detect open windows to avoid heating unnecessarily when you're venting the room or if you forget to close the windows.

Thermostatic valves and energy savings

Installing one or several thermostatic valves in your home allows you to make significant energy savings. By only heating the rooms you need to heat and depending on whether there are people in each area of your home, you can avoid having the heating on unnecessarily and cut down on the cost of your heating bill. With a smart thermostatic radiator valve you can even take advantage of warmth provided by the sunshine to further reduce your energy bill.

All thermostatic valves allow you to save energy. The more accurate the control is and the more suited the regulation is to your needs, the more savings you'll make. That's why it's best to invest in an advanced product, even though they're more expensive to buy. You'll quickly offset the price of your thermostatic valve by saving energy.

There are an estimated 5-25% savings to be made with a manual thermostatic valve, 15-25% with an electronic thermostatic valve and up to 40% with a smart thermostatic valve. Netatmo puts the average annual savings from fitting smart thermostatic valves to your radiators at €300.

Lastly, thermostatic valves work just as well on their own as with an atmosphere thermostat. This allows for even better regulation of the temperature in rooms and greater energy savings. By combining smart thermostatic radiator valves with a smart thermostat, you can limit your energy expenses as much as possible while also ensuring optimal comfort in your home.

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