A boiler is the primary component of any property’s central heating or hot water system, and gas boilers remain one of the most common types in Ireland. 

A boiler can be found in almost all homes and businesses in the country, and for many people, it may be time to upgrade to take advantage of more energy-efficient developments.

Gas boiler guide for homeowners

What is a Gas Boiler

A Gas Boiler is essentially a furnace, using gas as its fuel source, to create heat and hot water for your home or business. The thermostat controls the boiler and its two primary functions, central heating and hot water production.

How Does a Gas Boiler Work

Gas boilers work fairly simply. Gas is brought into the boiler, either from the mains of an LPG tank, and burned in the combustion chamber in order to heat water.

This fuels either the closed loop of the central heating system, where the hot water is pumped away from the boiler into the radiator, and returns as it cools, or creating hot water for taps in the home.

What happens with that heated water depends on the type of system you have. A Conventional Boiler will send it to a hot water tank for storage, while a Combi Boiler pipes hot water directly to taps.

The boiler is controlled by the thermostat which is used to determine whether the central heating or hot water is on, as well as controlling the preferred temperature.

Gas Boiler Components

There are many components in gas boilers which are common to all types of systems and some which are only found in specific variations. The three primary components of the boiler as the gas valve, the combustion chamber, and the heat exchanger

These three create the necessary conditions for using gas to boil water. Other components ensure the safe operation of the boiler and the effective flow of water around the system.

The valve is what controls the flow of gas from the gas mains or tank into the combustion chamber of the boiler.

As the name suggests, this is where the natural gas is mixed with air and burned in order to provide the heat for boiling the water. The process occurs very quickly, and the chamber can reach hundreds of degrees in heat.

This is a special chamber where heat can pass from the burning gas into water without having those two substances meet, creating the hot water needed for the heating system. A coil in the exchanger chamber is surrounded by water. This allows the heat to be passed from the heated gas into the water.

This does exactly what the name suggests, pumping the heated water from the boiler out into the central heating system or for use in the property.

Only found in Regular/Conventional Boilers, the expansion tank is a separate component which protects the boiler from excessive water pressure.

Found in conventional boilers and usually located in the attic or another elevated area, this provides the feed of cold water into the boiler.

With Regular and System Boilers the hot water created by the boiler is sent to the hot water cylinder for storage and later use throughout the property.

The exhaust flue expels the waste products created by the boiler such as water vapour or gases to the outside of the property to ensure that there is no dangerous buildup.

Types of Boilers

There are three main types of boilers separate from whether we are talking about gas, oil, electric, or biomass as a fuel source. These are:

  • Regular Boilers
  • System Boilers
  • Combi Boilers

All of them operate the same basic function of burning gas to heat water. The main differences between them are related to water storage methods.

Types of Boilers

Regular Boiler

A Regular Boiler, or Conventional Boiler has two separate circuits, heating water for the central heating system in a closed loop, and being fed water from a cold water tank for hot water needs. This water is pumped to a hot water cylinder where it is stored for later use. 

The hot water cylinder is ideal for households with multiple people as it can sustain greater demand in a short period. However, once it is used up the boiler has to heat an entire tank of water again. This can be inefficient if it leaves more water than is needed at the end of the day.

System Boiler

A system boiler works in much the same way as a regular boiler except that it has fewer parts, making it simpler to install and maintain. It will also take up less space. The main difference is that there is no separate cold-water tank or expansion cylinder in a system boiler.

The system is fed directly from the main rather than needing a cold water tank, and the function of the expansion cylinder is built directly into the boiler.

Combi Boiler

A Combi or Combination Boiler is so called because it combines the hot water and central heating systems within a single unit. Rather than having a cold water cistern and a hot water tank, Combi Boilers are connected directly to the water mains, and produce hot water on demand extremely quickly.

Combi Boilers are highly efficient and take up very little space. However, their weakness is that the lack of a hot water tank can make them unsuitable for homes with higher demand for hot water, or which have low water pressure. 

If multiple people run taps at once the system will struggle to keep up, and they cannot run hot water and central heating at the same time.

Best Boiler Brands in Ireland

There are many brands of boilers in Ireland with differing strengths and weaknesses based on their cost, output size, system type, and warranties.

Customers should shop around to ensure they have the right boiler for their needs. Three of the most high-quality and popular brands in Ireland are:

Well known for producing extremely high-quality boilers with a wide range of power outputs, Worcester Bosch has market-leading warranties of up to 12 years.

Ideal Logic boilers are well known for their reliability and affordability, with affordable parts. The company is also known for having excellent customer service for Irish customers.

Another German brand, the Viessmann Vitodens range focuses on Combi and System Boilers with warranties of 7 – 10 years.

How Long Do Gas Boilers Last

The average lifespan of a gas boiler before it needs replacement will be in the area of 15 – 20 years depending on the quality of the boiler. An entry-level boiler might start to wear out after as little as 10 years, so it is generally recommended to invest in a product which is better value in the long term.

Warranties for gas boilers will depend on the manufacturer and the system model, but most will be in the range of 8 – 12 years.

How Much Do Gas Boilers Cost

The average cost of a gas boiler for the majority of customers will be somewhere in the range of €1,500 – €3,500 based on the make and power output, typically up to around 35kW for this price range.

Larger boilers up to 50kW in output suitable for very large homes or businesses can cost in the region of €6,000.

There isn’t much difference between the cost of Combi Boilers and Traditional Boilers themselves. However, the Combi Boiler will have a lower installation cost, as it’s simpler to install without needing a water tank. They are also less likely to have maintenance issues with the simpler system.

How Much Do Gas Boilers Cost

Grants for Boilers

The SEAI used to have a grant for homeowners to upgrade to more energy efficient boilers. However, that has since been discontinued as the government is pushing for heat pumps to take on a greater role in home heating.

You can improve the efficiency of your central heating system by installing heating controls, for which the SEAI does have a grant. This €700 flat rate grant is available for all homeowners, including landlords, and any property occupied before 2011 is eligible.

Heating Control Systems can include Thermostatic Radiator Valves (TRVs) which regulate how much heat flows into individual radiatwors based on the desired temperature of the room. 

7-Day Programmable Timer allows you to control how your home is heated daily and weekly to match when it is occupied. An Immersion Heater Time and Temperature Controls allow you to set when the immersion will come on, and the temperature it will heat the hot water cylinder to.

Grants for Boilers

Signs It Is Time to Get a New Boiler

Once you know what the expected lifespan of a boiler is, there are signs that you should keep an eye out for that will let you know that it could be time to start looking for a replacement.

If your boiler needs more frequent maintenance work than in years past, it is a clear sign that it is coming to the end of its effective use. While it can be worthwhile to extend the lifespan of a boiler, when the repairs are becoming too frequent then it can cost more than it is worth.

Even if your boiler is not breaking down, over time it will lose efficiency. That will result in increased costs and carbon emissions. Take note of the length of your warranty, and past that 15-year mark, it might be time to start looking for a replacement.

A clear sign that your boiler is no longer working as well as it once did will be increased fuel consumption and the rising costs that come with it. If your gas bills rise unexpectedly it would be worth getting a qualified technician to inspect it. If there is no easily repairable fault causing the problem, it could be a result of its age.

Oil Boiler v Gas Boiler

Oil Boilers and Gas Boilers are the two competing systems which still rely on burning fossil fuels for heat. Both systems have different strengths and weaknesses based on their convenience, energy efficiency, environmental performance, and costs.

The price of oil and gas can go up and down greatly, but natural gas prices are almost always more affordable than oil. This may vary if you are in a rural area without a gas mains connection, and have to rely on LPG tanks.

As oil boilers require you to stock up on oil ahead of time, it may be possible to get a good bargain for a bulk purchase when prices are low, while most with gas boilers will have to pay whatever the price is at the moment.

For people living in Dublin or other urban areas, there is a strong likelihood they will be able to connect to the gas main network, which would make a gas boiler much more convenient than having an oil tank outside your home.

The reverse may be true for people living in the countryside having to rely on an external fuel tank for oil or LPG.

Modern gas condensing boilers are more efficient than oil boilers in terms of heat produced per unit of fuel, with efficiency levels of up to 95%, nearly 10% higher than top oil boilers.

Oil Boilers tend to have more maintenance work requirements than oil boilers because of the field they burn. Burning oil will lead to a build-up of soot, which can interfere with the operation of the boiler. In addition, the oil filter will need to be cleaned or changed regularly.

Oil Boiler v Gas Boiler

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