Thermostats in a Central Heating System - Find out About the Different Thermostats in a Central Heating System and How They are Used to Control Temperatures

Summary: Heating controls, thermostats, room thermostats, heat sensors and how they are used in central heating systems. In this DIY guide find out about the different types of thermostat and how they are used in your home to control temperatures and the running of your boiler or heating system. Find out about digital and analogue room thermostats, programmable room thermostats, zone heating systems and how each can effect your heating costs.

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What is a Room Thermostat ?

A thermostat, be it mechanical or digital, simply allows the user to set a temperature which will be maintained whenever the time-clock is timed to be on.

By using a room thermostat to control your boiler you can control when you’re heating is switched on and in some cases even what rooms are heated, ensuring that you are not wasting money and heating energy when no one is home.

Programmable hard wired room thermostat

Programmable hard wired room thermostat

Drayton 2RF wireless programmable room thermostat system

2RF wireless programmable room thermostat system - Image courtesy of Drayton

This can also in turn help save you money on your heating bills and also help to save the environment by reducing your carbon dioxide emissions as heating systems in the home generally tend to consume the most energy compared to any other item.

Essentially by using a room thermostat you can set the required temperature that you would like your rooms to be and once this temperature is reached, your boiler is switched off.

Most of the major heating manufacturers (Honeywell, Siemens etc….) produce room thermostats and typically they are available in several different forms – wired and wireless and digital and analogue.

As it suggests, wired units are connected to the heating or wiring source via a wire and wireless systems operate wirelessly.

When it comes to digital or analogue there are also some decisions to be made. Typically analogue thermostats are cheaper and easier to operate in that they feature a dial that is turned to set the required temperature. The temperature settings are also easily visible above the dial and in this respect can be ideal if fitting in the home of an elderly person.

Honeywell analogue room thermostat

Honeywell analogue room thermostat - Image courtesy of Honeywell

Digital thermostats often tend to be more attractive to look at but in most cases are more expensive. Depending on the type of heating system that you have in your home can also depend on what features you can use with a digital thermostat e.g. Zone Heating Systems (manufacturers requirements apply). In some cases the user panel used to set times and temperatures can also be a bit tricky to figure out.

Honeywell digital room thermostat

Honeywell digital room thermostat - Image courtesy of Honeywell

Some of the benefits of room thermostats are as follows:

  • With a wireless room thermostat, the controls and sensor can be positioned anywhere in your home (needs to be an area with free flowing air, with no obstructions e.g. curtains, chairs) so that they give the most accurate readings. In most cases the temperature sensor does not need to be wired directly to the boiler
  • They constantly measure the temperature of the air in your home
  • You can set the temperature to any that you require at any time

Upgrading to a Digital Room Thermostat

A mechanical thermostat often maintains temperatures higher than required due to their inherent inaccuracy. If the room temperature is 1°C higher than the set-point, you are potentially using up to 10% more energy. Conversely when the heating is off, mechanical thermostats are slow to respond and the room temperature can fall between 3-5°C before the heating comes back on, making occupants uncomfortable.

Digital technology has helped to improve the accuracy of temperature measurement and therefore control. Accuracy of greater than 1°C is the norm. Rooms rarely exceed the target temperature and energy use is therefore minimised. Conversely the heating comes back on as soon as the temperature falls maintaining a stable temperature keeping occupants comfortable.

Digital technology applied to thermostats has given rise to a number of variants. Some of these include: Digital Thermostat, Programmable Thermostat, Programmable Thermostat for Heating & Hot water.

Many of today’s modern thermostats and heating systems can also be controlled over the internet. Obviously the system itself will have to have this feature built into it for you to be able to access it.

In essence, your heating controller/thermostat will be connected to the internet and using a web app (commonly downloaded to a smart phone or accessed via an account through the manufacturer’s website) you can log in and set the temperature for your heating when you are not even in the same country. One point to note is that these systems and setup can be expensive!

Why should I consider a Programmable Room Thermostat ?

A programmable room thermostat combines the time-clock function within the thermostat whilst offering additional features.

The main additional feature of a programmable thermostat is the ability to set different temperatures at different times of the day – known as comfort levels. As the temperature set-point can be made to match the lifestyle of the occupant, a programmable thermostat gives far more flexibility and greater energy saving. In addition, programmable thermostats also serve as a frost stat.

Building regulations now state that dwellings with total usable floor areas greater than 150M² should have more than one heating circuit with separate time and temperature control. A programmable thermostat is the perfect solution.

The lifestyle of the occupant determines whether a 5/2 day or 7day version is most appropriate. Manufacturers are increasingly offering 5/2 day versions as standard due to the reduced programming required.

Other Types of Thermostat and Controls to Consider

Zone Controls

As already mentioned above, zone controls allow you to heat rooms in your house independently of each other. For example if you are spending the evening watching TV in the living room, there is no need to heat the dinning room. By doing so, you can save money on your heating bills.

Wireless zone heating control system

Wireless zone heating control system

Boiler Interlock

This essentially turns your boiler off if neither a cylinder thermostat (the thermostat inside your hot water cylinder if you have one) or room thermostat require it to be on.

Cylinder Thermostat

Some homes feature a cylinder where all the hot water for your home is stored. In most cases this will be located in an airing cupboard. The water inside the cylinder is heated through an element (similar to that of a kettle). The cylinder itself should feature a thermostat. This ensures that the element inside the cylinder does not continue to heat the water past the required temperature.

The thermostat itself in most commonly fitted around a quarter of the way up the cylinder from the bottom. Normally they are set to around 60°C to ensure no bacteria is allowed to develop in the water.

Boiler Thermostat

This is normally located on the front of your boiler. It usually looks similar to a dial with temperature settings on it.

The majority of boilers will only feature 1 dial that will set the temperature for any water that is sent to both the radiators and the hot water cylinder but in some instances your boiler may have one for each.

By turning the dial you can set the desired temperature for heating the radiators in your home. This can be used in conjunction with boiler interlocks and also room thermostats if you have them.

TRV's - Thermostatic Radiator Valves

These are basically thermostats for your radiators. They work by restricting the flow of hot water to your radiator when the temperature that has been set is reached. As the TRV itself monitors the temperature of the air around it you will have to ensure that it is not restricted by anything.

Thermostatic radiator valve

Thermostatic radiator valve

If you would like to look further into the possibilities of saving energy and reducing your heating bills you can visit our Green Living area and fill out our quick and simple Energy Assessment form.

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