What does a new gas boiler cost?

Most heating firms will not put a price on a website. We will, because the question deserves an answer — and because you should be able to work out roughly what you are facing before anyone sets foot in your house.

Our guide prices

These cover a straightforward replacement in a typical 2 to 3 bedroom house — boiler out, boiler in, same position, nothing unusual needed.

Those are guide figures, not quotes. Every house is different and the honest version is that the boiler is the predictable part of the cost — what sits around it is where jobs differ.

What the price includes

• The boiler itself, and its manufacturer warranty registered in your name
• Full installation by a Registered Gas Installer
• Your old boiler removed and disposed of responsibly
• A system filter, fitted as standard
• Inhibitor added to protect the new system
• Commissioning, testing and full RGI certification

What moves the price, and why

This is the part that decides whether your job lands near the guide figure or above it. None of it is upselling — it is the work needed to make the installation safe, legal and compliant with I.S. 813, the Irish standard for domestic gas installations.

Gas pipework

The single most common extra. Modern boilers need a given gas flow, and older houses were often piped in a smaller diameter than a new boiler requires. If the existing run is undersized, the boiler will not perform correctly and the installation will not be compliant, so the pipework has to be upgraded from the meter.

How much that costs depends entirely on the route — a short run in an accessible place is straightforward, one that crosses the house under floors is not.

Flue routing and length

If the new boiler goes where the old one was and the flue can follow the same path, there is nothing in this. If the boiler moves, or the existing flue route does not meet current clearance rules for windows, doors and boundaries, the flue has to be rerouted or extended.

Condensate drainage

Modern condensing boilers produce acidic condensate that must be piped to a suitable drain. Older boilers did not, so there is frequently no drain anywhere near the boiler position. Getting that to a drain — and doing it so it will not freeze in January — is real work.

Ventilation

Required to meet I.S. 813, and depends on the boiler type and where it sits. A room-sealed boiler in a well-positioned spot may need nothing; a boiler in a confined press or an internal room may need a vent installed.

Earth bonding

Gas and water services have to be properly bonded to the electrical earth. In older houses this is often missing, undersized or has been disturbed by previous work. It is a safety requirement, not an optional extra, and where it is absent it has to be put right as part of the installation.

Carbon monoxide alarms

Where there is no alarm, or the existing one is past its service life — they expire, and most people do not realise it. A small cost and not one worth avoiding.

Moving the boiler

Relocating from, say, a kitchen to a utility room means new gas, water, heating and condensate runs, a new flue, and electrical work. It is the change that moves a price most, and it is worth being certain you want it.

Power flushing

A separate job, not part of a standard installation. Where a system is heavily sludged it is worth doing before a new boiler goes in, and some manufacturer warranties expect a clean system. We assess it at the quote rather than selling you a flush you do not need.

Changing boiler type

Going from a system boiler to a combi — or the other way — is a bigger job than a like-for-like swap. The cylinder and often the attic tanks come out, pipework is reconfigured, and the hot water arrangement changes completely. Our combi boiler guide covers whether it is the right move for your house.

Heating controls

If your controls are ancient, it is worth upgrading them while the system is open rather than paying for a second visit. See heating controls and Hive, and the €700 grant that may apply to the work.

Why nobody can price this over the phone

People ask, and we understand why — but a price given over the phone is a guess, and guesses get corrected once the work has started. That is the conversation nobody wants on day one.

The gas pipe size, the flue route, where the nearest drain is, the state of the bonding: none of that can be established down a phone line. We look at the job, then give you a written price covering everything, so the figure you agree is the figure you pay.

Should you replace it at all?

Worth asking before spending thousands. Our view is that a boiler is generally worth repairing until it is fifteen to twenty years old, assuming parts are still available and it has not failed repeatedly.

A ten-year-old boiler with one fault is usually a repair, not a replacement, whatever anyone tells you. An €80 call-out will establish which situation you are in, and an annual €110 service is what keeps a decent boiler out of that conversation for years.

And if you were hoping a grant might help with the cost — there is no SEAI grant for a gas boiler, and has not been since January 2025. Better to know that now than halfway through an application. If that has you wondering about going off gas entirely, the heat pump or gas boiler comparison covers what that actually involves — including the fortnight of upheaval a heat pump brings against a day for a boiler swap.