Frequently Asked Questions

Servicing Your Boiler

Replacing Your Boiler

Boiler Controls

Who should I get to service my boiler?

As with all heating appliances, your boiler should be serviced on a regular basis to ensure that it is operating efficiently and safely.  The service should be carried out by a qualified and experienced service technician / service engineer. 

More information regarding boiler service providers and service contractors can be found below:

FuelTypeOilNatural GasLPG
ContactOFTECRegister of Gas Installers of IrelandIrish Liquid Petroleum Gas Association (ILPGA)
Phone01 86457711850 632 63201 450 5000 / 041 9831 041

Why should I service my Boiler?

An annual boiler safety check and boiler service, carried out by a professional service engineer ensures that your boiler is functioning properly.  Regular servicing of your boiler is important as it ensures that the boiler is working to the specifications designed by the boiler manufacturer. This will help prolong the life of the boiler as well as reduce the risk of faults and expensive repairs down the line.

The efficiency of boilers, both oil and gas fired, deteriorates with use. There are several reasons for this, the key ones being:

  • Soot production from the combustion process coats the heat exchanger surfaces.
  • The critical air-to-fuel combustion ratio changes due to gradual component wear.

A boiler service will remove any sooting and, by adjustment, will re-establish the optimum combustion conditions. But while optimising operating efficiency is paramount in these days of rising fuel costs, there are other important benefits in having your boiler serviced:

  • By checking the safety controls, early failures can be detected and rectified in good time.
  • A variety of operational systems and components will be checked including:

- Gas/Oil leaks
- Boiler start-up performance
- Noises that give an early warning signal of pending component failures.

Just like cars, boilers can operate for many years without servicing but generally with fuel consumption penalties, undermined reliability and even safety implications.

What should I expect when a service engineer arrives?

When carried out by a competent technician, a boiler service should entail little disruption to your routine.  A typical service should take around an hour and leave you with a safe and efficiently operating appliance.

A service engineer will perform a number of tests on the boiler during a service. This will depend in part on the fuel and boiler. While there is no set standard or regulation specifying what constitutes a boiler service at this time, we have prepared checklists of the type of work that the Service Technician should carry out during the course of a typical service. 

These checklist can be downloaded in PDF format below:

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Is there really a benefit to servicing my boiler?

Because of the difference between individual installations, it is difficult to predict what saving servicing will bring for a particular house.

The following chart is conservative and gives the increase in fuel costs each year that the boiler is not serviced.

Fuel Savings from Boiler servicing Line Graph showing savings made by servicing based on boiler fuel type

For example, servicing a kerosene boiler, which has not been serviced for 3 years, will bring about an immediate fuel reduction of some 5%.

How often should I service my boiler?

Most boiler manufacturers recommend an annual service, primarily on the grounds of safety but also to ensure reliability. On efficiency grounds it is well worth servicing oil boilers annually because the soot build-up is such as to significantly increase oil consumption. With gas, while soot build-up is not so much a problem because of its clean burning characteristics, an annual service would still be recommended.

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What do I do if my boiler is more than 15 years old?

Typically, the “as new” efficiency of an oil or gas boiler over 15 years old would have been less than 80%. It’s present efficiency today, due to wear and tear is unlikely to be greater than 70%.

The current range of boilers available today will have efficiencies greater than 90%. This represents an operational improvement in efficiency of up to 20 percentage points

Increasing the operational efficiency of your boiler by this amount represents an actual fuel saving of more than 25%.  In other words, by replacing an older, low efficiency boiler with a new, high efficiency boiler, you can cut your fuel bills by a quarter.

So, replacing old boilers makes good sense for two reasons:

  • Significant fuel cost savings with can only increase as energy prices escalate.
  • Improved reliability and safety.

If you have a boiler older than 15 years then it is most likely during the next few years that you will have to replace it on reliability grounds in any case. Change it now and start saving immediately!

By planning the change (rather than it being forced on you in the depth of winter when it breaks down) you can get competitive quotations and reduce the cost.

Hint: Remember, replacement costs are lower in summer

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Oil, Gas, what’s the best type of replacement boiler for me?

When replacing a boiler, the first consideration should be about which fuel to use. Generally, you should consider replacing your boiler with one that uses the same fuel. If you have a natural gas supply then it is likely to be the lowest cost option in terms of both boiler installation cost and running cost. If you don’t have a natural gas supply then the choice is between oil, LPG or pellet boilers. For rural areas or areas that are off the national gas grid, oil or LPG are viable solutions. 

Please click here for more information on wood pellet boilers

Should I install a condensing boiler?

Where possible, you should consider installing the highest efficiency boiler possible.  Condensing boilers have a much higher efficiency than non-condensing boilers, however there are some rare situations where installing one may not always be feasible.

Since March 31st 2008 when installing a replacement oil or gas boiler it is now a requirement that the boiler be condensing, where practical (Section L3, Building Regulations Part L amnement – S.I. No. 847 of 2007:-

A guide to assess specific situations where the provision of condensing boilers is not practicable can be downloaded here: Condensing boiler installation for existing dwellings.pdf (size 353.4 KB)

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What’s a condensing boiler and how does it work?

Condensing boilers are highly efficient. They use less fuel and have lower running costs than other boilers. Higher efficiency levels are made possible by extracting heat contained in the combustion gases, which would otherwise have been lost to the atmosphere.

This is because both oil and gas contain hydrogen locked within their chemical structure. When oil or gas is burned, the hydrogen links with oxygen in the air to form H2O (water). This water (as vapour) can be seen from the exhausts of cars on cold days. The vapour (or steam) contains about 8% of the total fuel’s energy and capturing it makes energy efficiency sense. This is exactly what condensing boilers do. They “condense” the vapour and capture the energy contained there, making modern boilers so much more efficient.

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What’s a combi boiler and how does it work?

Combination boilers are capable of providing instant hot water and heating while saving space within a home.

The conventional arrangement in Ireland is to have a normal boiler which heats the radiators via a sealed water circuit. By “sealed” it is meant that the water is contained within the system, going around in a loop between the radiators and the boiler.

To heat the “domestic hot water” (i.e. the water that comes out of the hot taps) the storage cylinder in the hot press has a coil in it through which the “radiator water” flows.

The disadvantage with this arrangement is that if the cylinder does not have hot water in it you have to wait some time for the coil to heat it up.

A ‘combi’ boiler is a boiler which combines both a conventional boiler for radiators and an independent water heater, together in the one unit. This dispenses with the hot water cylinder in the hotpress. But better still, it means that hot water is always available instantly and for as long as you need it.

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Where can I find more information about the efficiency of boilers and where to purchase them?

The SEAI HARP (Home-heating Appliance Register of Performance) database maintains a list of all oil and gas boilers, and their efficiency, that are available on the Irish market. This list is available on our website at

Who should I get to install my boiler?

Your boiler should be installed a qualified and experienced boiler installer. A good installer will be able to size your new boiler based on the actual heating requirements for your home. This will ensure that the boiler operates at its optimum capacity and be most cost effective. 

We recommend that you should check that the installer holds public liability insurance and that they have the necessary qualifications and experience to carry out the works in question.

More information regarding boiler service providers and installers can be found below:

FuelTypeOilNatural GasLPG
ContactOFTECRegister of Gas Installers of IrelandIrish Liquid Petroleum Gas Association (ILPGA)
Phone01 86457711850 632 63201 450 5000 / 041 9831 041

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“What difference do controls make?”; “What are the best types?”

Controls have come a long way in the past ten years and they afford an excellent way to improve comfort conditions and save energy.

Controls have two primary functions:

  • Deciding when the heating system comes on and goes off. It is a good idea (and a requirement for new installations) to divide the house into zones (eg living areas and bedrooms) and to have separate timeclock control over each zone.
  • Maintaining a pleasant comfort level in the rooms. The most cost effective way of achieving this is by fitting thermostatic valves to radiators. These valves automatically regulate the radiator heat output to provide a constant temperature in the room.

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