Prices · read 28 October 2026
System to combi conversion
Losing the cylinder and tank costs more than a straight swap. Here's the Dublin price and whether it suits your house.
Figures checked against installers' published price pages on 28 October 2026.
Converting from a system or regular boiler with a hot water cylinder to a combi costs more than a straight swap. Dublin Plumbing & Gas prices a gravity-fed system to combi conversion at €3,100–€3,850 (14 September 2026). GB Gas Services says converting typically adds €600–€1,200 to a straight swap, incl. VAT.
You lose the cylinder and the attic tank and gain a hot press. You also lose stored hot water, which matters in a house with several bathrooms.
What the conversion involves
The old boiler, the hot water cylinder in the hot press and the cold water tank in the attic come out. The pipework to the taps is changed so hot water comes straight from the combi at mains pressure. The installer caps or removes the old pipes, fits the combi, flushes the system and commissions it. Dublin Plumbing & Gas puts the extra cost down to the labour of decommissioning the tanks and re-routing the hot and cold feeds.
Dublin prices
| Job | Price | VAT | Source |
|---|---|---|---|
| Gravity-fed system to combi | €3,100–€3,850 | Not stated | Dublin Plumbing & Gas, 14 Sep 2026 |
| Extra on top of a straight swap | +€600–€1,200 | Incl. | GB Gas Services, 19 Oct 2026 |
| Regular boiler + cylinder to combi, boiler stays in place | €3,995 | Incl. | Gasworks, in Boiler Service Dublin's survey, 23 Oct 2026 |
| Same, boiler in a new spot | €4,495 | Incl. | Gasworks, same survey, 23 Oct 2026 |
Read 28 October 2026.
Good fit, poor fit
| Usually a good fit | Think twice |
|---|---|
| One main bathroom | Two or more showers used at the same time |
| Good mains water pressure and flow | Weak mains pressure or a long, thin supply pipe |
| You want the hot press and attic space back | You plan a heat pump soon (it needs a cylinder) |
| Old cylinder or tank leaking or failing | An electric shower or solar water heating you want to keep using with a cylinder |
Before you agree a price
- Ask the installer to test your mains flow and pressure
- Ask what happens to the old cylinder, tank and pipes
- Ask if any shower pumps or electric showers need changing
- Get the price with VAT stated
- Ask how long the house is without hot water
The full guide
Our sister site has a longer guide on converting to a combi boiler, with prices from installers around Ireland and the questions to ask. If you're in Dublin and want a fixed price, use the price check on this page.
Questions people ask
How much does it cost to convert to a combi in Dublin?
One Dublin firm prices a gravity-fed system to combi conversion at €3,100–€3,850. Another says converting adds about €600–€1,200 to a straight swap, incl. VAT.
How long does a conversion take?
Longer than a straight swap, because the cylinder, tank and pipework come out. Ask the installer: it depends on the house.
Is a combi right for a big family?
Not always. A combi shares its hot water between taps. If two showers often run at once, a system boiler with a cylinder may suit better.
Sources (2)
Prices and facts on this page were checked against these published pages. We are not connected to these businesses.
- Dublin Plumbing & Gas: dublinplumbingandgas.com
- GB Gas Services: gbgasservices.com
See your price, then get a fixed quote
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