New Boiler Swansea: Fitted by Gas Safe Installers

Swansea has more detached and semi-detached homes than Cardiff, together nearly 60% of households. Larger houses with more radiators and bathrooms need careful sizing, and a like-for-like swap isn't always the right answer.

Most homes will stay on gas for now: 80.3% heat with mains gas only. But with only 38% of the city's homes rated EPC C or above, insulation is worth looking at alongside a new boiler.

Swansea at a glance

Water hardness: Soft. Welsh Water's postcode checker lists the Swansea / Morriston, Sketty / Gower, Townhill and Cray / Clydach supply zones, fed from Felindre and Cray, as soft. Source
How homes are heated: 80.3% of Swansea households heat with mains gas only and 5.6% with electricity only. 1,959 homes (1.9%) rely on oil alone and 1,066 (1.0%) on tank or bottled gas. Source
Housing mix: 34.5% of Swansea households lived in semi-detached houses in 2021, 25.4% in terraces and 24.0% in detached houses. Flats, maisonettes and apartments made up 15.9%. Source
Median energy score: About 53% of homes with an EPC in Swansea are rated band D or below (median score 68, band D), against 53% across Wales. Based on certificates lodged in the 10 years to March 2025. Source

Sizing for the house you have

Ask each installer for a heat loss calculation. An oversized boiler cycles on and off, wears faster and wastes gas. For a detached house in Sketty or Killay with two bathrooms, compare a combi with a system boiler and an unvented cylinder before you decide.

In a three-bed semi with one bathroom, a combi of the right size is often the simplest and cheapest choice.

Soft water changes the spec

Because Swansea's supply is soft, installers here usually don't need to fit a scale reducer on the cold main. Spend that money on a magnetic filter, a proper chemical flush of the old system and good controls instead.

Access and flues

On steep streets with no rear access, getting the old boiler out and the new one in can take planning. If a flue has to move, the installer should check it against the clearances for windows, doors and boundaries. Ask them to explain where the plume will go, especially if it faces a neighbour's window across a narrow lane.

Off the gas main?

If you're on oil or LPG, a heat pump may now cost less to install than you think. The Boiler Upgrade Scheme pays £7,500, plus £1,500 more for oil or LPG homes until March 2027.

Swansea homes and what they need

Hillside Victorian and Edwardian terraces

A compact combi in the kitchen or a bedroom cupboard suits most terraces. Check the gas pipe is big enough for the new boiler, as older supplies often need upgrading.

Interwar and post-war semis

Replacing an old back boiler means a new position and a new flue, often on a side wall. Ask for the removal of the old fire and back boiler to be priced in.

Waterfront and city-centre flats

Flue options are limited in flats. Leaseholders should check the lease before changing anything on the outside wall.

Areas covered

Engineers who cover Swansea work across areas including Sketty, Uplands, Mumbles, Killay, Morriston, Townhill, Brynmill, Gorseinon, Pontarddulais and Clydach.

View Swansea on Google Maps

Questions people in Swansea ask

Does Swansea's soft water affect boiler life?

It helps, as less scale builds up on the hot water side. Sludge from corroding radiators is the bigger risk, which is why a filter and a flush matter.

How long does a boiler swap take in Swansea?

A like-for-like combi swap usually takes one to two days. Moving the boiler or converting from a regular system takes longer.

Sources

Also nearby: Boiler installation in Cardiff

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