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Central Heating

Your central heating system is one of the most important elements of your home and life. A properly installed and maintained system will not only reduce your annual fuel bills but will also increase the comfort of your home.

Whether you are considering installing a new energy efficient central heating system, upgrading your current central heating system, or simply looking for more information on the heating system you currently have in place. We have created a simple guide for you to familiarise yourself with the diffeCentral Heating System Layoutrent types of heating systems available in Ireland and how they work.

  • Gas Central Heating

  • Renewable Heating Systems

  • LPG Central Heating

  • District Heating Systems

  • Oil Central Heating

  • Bio Mass Heating Systems

Central Heating Replacement Cost

How much does central heating cost? The cost of replacing your current heating system with a new energy efficient system varies greatly. Factors that are most likely to influence the costings are:

Fuel Type – The choice of fuel used for your central heating will have cost impacting implications during both the installation and running costs. This will also affect the property BER Rating. The main types of fuel available for central heating systems are Natural Gas, LPG Gas, Home Heating Oil, Bio Mass, Solar, Renewable Energy (Heat Pumps) and Electricity.

Property Size – The property size is the one of the main factors that influences the costs involved in installing a central heating system in your home or business. The larger the property, the bigger the heat load. Installation time and materials can also be expected to increase or decrease dependent on the property size.

Number of Rooms – Depending on the type of central heating system you have chosen the number of rooms in a property can affect the variables in cost. This is especially true when we consider underfloor heating or warm air heating systems.

Types of Heat Emitters – The choice of heat emitters will undoubtedly impact cost. Radiators/Heat Emitters come in many different designs and materials from hospital type, column type, flat panel, vertical radiators and high efficient aluminium radiators. The difference in pricing between some of these radiators can exceed 500%.

Underfloor Heating – When compared to the conventional radiator heating system, an underfloor heating system will cost more to install. Although more expensive to install, savings can be expected due to the low operating temperature of an underfloor heating system. Underfloor heating systems are most suited to new builds or property undergoing major renovations.

Number of Heating Zones – How many heating zones you require will increase the installation and maintenance values of the central heating system. At a minimum you will require time and temperature control for both space heating and hot water demand.  For every additional heating zone needed additional piping, cabling and controls will be required.

Heating Controls – Your choice of heating controls will not only affect price but will also affect your home heating comfort and lifestyle. From Basic Central Heating Control to fully fledged multi-zone internet controlled heating systems.

Hot Water Demand – Hot water demand is often overlooked when installing a central heating system. The Larger the buildings hot water demand the larger the cylinder/boiler required. This can be subsidised by solar hot water heating or by other renewable energy means.

Multi Fuel Heating Systems –  Multi-Fuel Heating systems are heating systems that have multiple energy sources such as an oil boiler, solid fuel  boiler stove, heat pump, gas boiler.

Installation Difficulty – Naturally the more difficult and labour intensive the given central heating installation , the more costly it will be.

Magnetic Filter –  Installation of a magnetic filter will not only protect your boiler and other system component but it will also maintain efficiency. The given size is dependent on the boiler output


What is central Heating?

To put it simply a Central Heating system provides the heat energy required to warm the building interior to the desired temperature. This is done from a central heat source, such as a gas or oil boiler.  The Heat Energy produced by the central heat source is then distributed around the building. This is usually done through distribution piping or ducting.


One Pipe System 

As the name suggests a one pipe heating system consists of a single pipe which carries the heated water from the gas boiler to the radiators. This type of central heating system is usually recognisable as the single pipe is more often than not surface mounted and routed below the radiator. The piping connections on the radiator will be top connected for the flow and the return bottom connected. This makes the direction of flow easily recognisable, both the feed and the return piping connections join the same pipe underneath the radiator.  

The main advantage of a one pipe central heating system over a conventional two pipe has is low installation costs in both time and materials. The disadvantage of such are system is it is difficult to balance, as each radiator on the central heating system will receive water than has been mixed with cooler water returning from the previous radiators on the central heating circuit. The result of this means the further the radiator from the boiler the lower the surface temperature will be. To compensate for the lower achievable water temperatures radiators may have to be larger than expected. 

Two Pipe System2 pipe radiator system 

The most popular central heating system in Ireland. Recognisable by two separate pipes going to each individual radiator. The two-pipe central heating system has two independent pipes as part of the central heating piping circuit, one serving the flow the other acting as the return.  With this type of heating system once the heated water has passed through a radiator it returns directly back to the central heating boiler where it is reheated.  

The advantages of a two-pipe system are: 

1) The higher velocity of the central heating systems water results in a quicker heat up time in compassion to the one pipe system. 

2) The radiators can be suitably balanced to achieve an even heat output throughout the central heating system, this allows for smaller radiators yet resulting in a better preforming more comfortable system as a whole. 

3) Additional radiators can be easily added (dependent on boiler output) 

4) When installing a condensing gas and oil boiler, the required flow and return temperature difference can be easily achieved. 

The Disadvantages of a two-pipe heating system are its costlier to install in both time and materials 

Micro bore Central Heating System 

A micro bore heating system is recognisable by the small diameter piping connections to the radiators. Typically, 8mm but can be between 6mm and 12mm. These smaller diameter pipes equal a lower water content within the heating system. This makes for a rapid response to any heating demands.  Unfortunately, poorly maintained micro bore systems are prone to blockages and many systems cannot be restored resulting in complete or partial piping replacement.




There are three main types of central heating in Ireland Wet, Dry, and electrical storage heaters.

Wet (water) Central Heating Systems

The most popular form of central heating in Ireland. In a wet heating system a boiler generates heat which is circulated through a network of piping throughout the property. The piping is connected to radiators which are used to warm the air in the building through convection. Additionally the hot water cylinder can also utilise the central boiler as its primary heat source, providing the property with a cost effective hot water solution. This is usually the case throughout the many homes around Ireland.

Dry Central Heating Systems

Dry Heating is effectively a warm air heating system. It works by blowing heated air through a series of ducts. The ducting transports the heated air from the central heat source and delivers it to the rooms within the property, and is usually powered by gas, oil or electricity.

Electrical Storage Heaterselectrical central heating

Electrical Heating systems use electricity as the single source of power, it can be a heating system primarily consisting of electric storage heaters or can be much like a wet conventional heating system, but instead of being powered by gas or oil is powered by an electric boiler.



Zoned heating controls

In Ireland the most popular forms of domestic central heating are gas and oil fired systems. The maintenance and condition of domestic heating systems and components are often overlooked by the occupants. Understanding basic heating systems and their components will help not only in the maintenance requirements, but will also give you the basic yet essential knowledge needed when deciding if you require expert assistance.

The Boiler

The main component of a central heating system, the boiler produces the heat energy (Kilowatts) required by the property. There are many different types of boilers available on the market today and just like cars the costing vary greatly.

Types of Central Heating Boilers

Heat Only Boilers –  This is the most basic type of boiler available, it is suited to open vented heating systems.

System Boilers – System Boilers are the most popular boiler installed in Ireland today. The system boiler incorporates a circulation pump, automatic by-pass, expansion vessel and pressure relief valve plus a range of other features.

Combination Boilers – Known simply as combi boilers, this boiler will provide you with instant hot water on demand as well as your property’s heating requirements.

Boiler Efficiency

  • Band A 90% and above
  • Band B 86%-90% efficient
  • Band C 82%-86% efficient
  • Band D 78%-82% efficient


Radiators/Heat Emitters

Radiators are the most common method of Heating in Ireland. There are many types of radiators available today with the most common made from mild steel with convector fins for effective heat transfer. A radiator works by warming the air through convection currents, as the cold air passes over the surface of the radiator it is heated causing it to rise and in turn push the cooler air down, this process is repeated resulting in the air temperature rising.

Underfloor Heating

In an underfloor heating system, plastic piping is ran in the floor for the purpose of space heating. Underfloor heating requires a very low operational temperature when compared to the traditional radiator heating system. Underfloor heating systems are more costly to install but when installed and maintained correctly are cost effective to run.

Expansion Vessel

Used in a sealed heating system, the expansion vessel as the name suggests allow for additional expansion of water within sealed systems. When the water within the central heating system is heated its volume increases, this additional volume is absorbed by the expansion vessel.

Circulation Pump

The circulation pump moves the heated water from your boiler around the central heating system. In The event of pump failure the central Heating system will not function.

Pressure Relief Valve

The pressure relief valve or safety valve as it is otherwise known is designed to operate in the event of over pressurisation of the heating system. Common causes for this are expansion vessel failure or simply a mains fill valve left in the open position.

Central Heating Piping

Piping requirements for central heating systems can be meet by either suitable pex or copper piping. The type of pipework and jointing methods is dependent upon a number of factors, such as practicability and costing. If you need advice or guidance a member of the Gasworks Ireland Team would be delighted to assist you.

Feed and Expansion Tank

The Feed and Expansion tank is a small water tank that will is usually located in the attic space. The feed and expansion tank is part of an open or unsealed heating system. It serves as both a cold water top up tank and expansion tank. As the water in your heating system is heated the volume of water in the system increases, the feed and expansion tank will cater for this increase in water volume.

Thermostatic Radiator Valves

Thermostatic Radiator Valves or TRV’s as they are also called are basically a mechanical thermostat. They work by sensing the surrounding air temperature, and in turn regulate the flow of water within the radiator to which they are fitted. They do not provide boiler interlock.

Motorised Valve/Actuator

Motorised Valves or zone valves as they are also known provide full zone control for both space heating and hot water heating. These electrically controlled valves offer full system control whilst also providing boiler interlock. They are available in both 2 and 3 port versions with 2 port being the most common.

Room thermostat

Room thermostats control the temperature of the air in the zone to which they are fitted. When the temperature of the air in the selected zone is below the value selected on the thermostat the heating will remain on. When the target temperature is reached the thermostat will switch of the boiler. This results in a more comfortable environment and cheaper annual fuel bills.

 Boiler Thermostat

The boiler thermostat controls the temperature of the water leaving the boiler. The higher the boiler thermostat the hotter the radiators will be. The boiler will usually have a dial through which this temperature selection can made.

Cylinder Thermostat

The cylinder stat controls how hot your stored hot water will be the higher the value the hotter the water at the tap. It is advised that a minimum target temperature of 60°C is selected. This will remove any risk posed by legionaries disease.

Timer Clock/Programmer

The Time Clock is the main control unit for the central heating system it is from here that the on/off periods for your heating system can be selected. There are vast range of time clocks available on the market today with the most basic being a single channel manual timer.


There are wide range of fuel types available for central heating purposes. The most common fuel types in Ireland at present are:

Natural Gas – Piped directly from the Gas network, this may not be available to some homes and businesses.

LPG (liquid petroleum gas) – Bulk stored in a suitable gas tank.

Kerosene – Bulk Stored for use in a suitable oil tank

Gas Oil – Bulk Stored for use in a suitable oil tank

Biomass – Wood, logs, pellets and chippings

Electric – Utilises Electricity as the energy source (Heat Pumps)

If you are renovating your existing central heating system, building a new home or simply looking to replace a couple of radiators in your home, this guide will help you make the right choice. We also have a team of expert heating advisors available to assist you, should you require. 

Heat Output of Radiators 

The single most important factor to be considered when deciding on which type of radiator best suits your needs is the heat output and I think you’ll agree. After all the purpose of the radiator is to warm the given area or room to the required temperature. At this stage it is important to know the energy required for the room, this can be done using our heat calculator as a guide. The operational water temperature of the central heating system will also impact on radiator type and size. For example, if you have a Heat pump installed the operational temperature will be lower than a conventional high temperature Oil or Gas Heating system. This will result in larger radiators to achieve the required outputs. Other factors that will influence the required radiator size and type will be, the room layout and size, aesthetics, windows, doors, open fire and of course the level of insulation.  

Radiators Size and Position 

Regardless of the chosen radiator style and size, it is proven that the best place to site a radiator is in the coolest part of the room, quite often this may under the window, close to outside doors etc. If your chosen radiator location is under the window, curtain length must be taken into consideration as they may impede the circulation of air when fully drawn. In the case of wall mounted radiators, it is also important to maintain a minumum distance of 150mm from the finished floor to the underside of the radiator. This allows for an adequate flow of air from the rad. 

Radiant and convected heat 

Although called radiators, they give off very little radiant heat. It’s actually through convection currents that the bulk of the heat generated by the rad is given to the room. They warm the air by exposing a large heated surface area which in turn sets up convection currents in the room. The larger the surface area of the radiator the greater the heat transfer will take place. It is for this reason the large majority of pressed steel radiators will have convector fins fitted to the rear.  

In the case of radiant heat, increasing the frontal area will increase the amount of radiant heat given to the room. As radiant heat from a hot radiator will naturally be felt before convected warm air, the size and type of radiator will affect the heat output which in turn will affect the comfort levels. 

The heat up of the room through convection depends on a number of factors some of which are: the intial air temperature of the room, the height of the ceiling and any draughts from the outside that may be present. Taking this into consideration a larger single panel radiator will achieve a quicker room comfort than a double panel radiator of the same heat output. 

Heat Output of Double and Single Panel Radiators of the same dimension 

Radiator Type                             Size  H x L                                Watts                                        Btu’s per hour 

Single Panel Radiator               500mm x 800mm                     712                                              2430 

Double Panel                             500mm x 800mm                     1270                                            4335 

Radiator types and styles 

Aluminium Radiators – Aluminium radiators are an ideal solution when it comes to low temperature central heating systems such as air to water heat pump systems. They have a lower water content than traditional steel radiators and a higher heat transfer rate. Therefore, aluminium radiators generally require a lot less energy to achieve the same room temperatures when compared with radiators manufactured from other materials. Aluminium is also lightweight, non corrosive material than maintains its quality very well. Cost is the main down side of aluminium radiators. 

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