Combi boiler replacement in Dublin

Figures checked against installers' published price pages on 28 October 2026.

How to tell if you have a combi

A combi heats water as you use it. There's no hot water cylinder in the hot press and no cold water tank in the attic feeding the hot taps. If you have a cylinder, you have a system or regular (heat-only) boiler, and swapping to a combi is a bigger job: see system to combi conversion.

Combi replacement prices in Dublin

Read 28 October 2026. A "from" price is the smallest boiler in that firm's range.

What changes the price of a combi swap

• Output. A combi has to heat water for the taps instantly, so it's sized on hot water flow as well as on radiators. More bathrooms, more output, more cost.
• Brand and warranty. Ideal, Worcester Bosch, Viessmann and Vaillant all make combis at different price points. Warranties on the Dublin price lists in Boiler Service Dublin's survey run from 2 to 12 years.
• Flue. If the new flue can come out where the old one did, it's quicker. A new route through the wall or roof adds labour.
• Position. Keeping the boiler in the same place keeps the pipework the same. Moving it to the attic or a utility room is a bigger job.
• Water pressure. A combi works off the mains. If your mains pressure or flow is poor, the installer should check it before fitting a bigger combi.

Signs a combi swap is the right call

• Your combi is old and breaking down more often
• Parts for it are getting hard to find
• One bathroom, or two that are rarely used at once
• You're happy with how the heating and hot water work now, and just want it reliable
• The boiler is in a sensible spot and doesn't need to move

When a combi isn't the right swap

A big house with several bathrooms in use at the same time can struggle on a combi, because the hot water is shared between taps. A system boiler with a cylinder stores hot water for that. If you're planning a heat pump in the next few years, a heat pump also uses a cylinder. See gas boiler or heat pump?

What happens on the day

1. Survey first.The installer checks the boiler, the flue, the gas pipe size and the mains water. You get a fixed price.
2. Old boiler out.The system is drained and the old combi taken off the wall.
3. Clean the system.A chemical flush clears sludge. A magnetic filter goes on the return pipe.
4. New combi in.Boiler, flue and controls are fitted, the system is refilled and inhibitor added.
5. Commission and certify.The RGI tests the gas, sets the boiler up and gives you the completion certificate.
6. Register the warranty.Ask for proof it's registered with the maker.

A straight combi swap is usually done in a day. By law, gas work in Ireland must be done by a Registered Gas Installer (CRU). You can check any installer on rgi.ie.

After it's in

Book a service for a year's time. Most warranties depend on it, and on a magnetic filter being fitted. Boiler Service Dublin lists what a gas service should cover and what Dublin engineers charge.

Questions people ask