New Boiler Cardiff: Gas Safe Installation Quotes

Most Cardiff replacements are a straight gas-to-gas swap, since 78.4% of households heat with mains gas alone. The choice that matters is the type of boiler, how it is sized and how it is protected, not just the brand on the front.

Cardiff at a glance

Water hardness: Moderately hard. Welsh Water's postcode checker places the Cardiff Bay / Canton / Cathays, Heath & Llanishen and Ely / Radyr / Llandaff supply zones, and Penarth / Barry, in its moderately hard band. Much of west Wales, including Swansea, is soft. Source
How homes are heated: 78.4% of Cardiff households heat with mains gas only and 10.4% with electricity only. Oil-only heating covers 209 homes (0.1%), and 456 homes (0.3%) are on a district or communal heat network. Source
Homes that are flats: 26.5% of Cardiff households lived in a flat, maisonette or apartment in 2021: 20.2% in purpose-built blocks and 5.0% in converted or shared houses. Another 29.6% lived in terraced houses. Source
Nest scheme: Nest, the Welsh Government's scheme, funds heat pumps, insulation and solar panels for owners and private renters on means-tested benefits or low incomes whose home is rated EPC 54 (E) or lower, or 68 (D) or lower where someone has an eligible health condition. Source
Median energy score: About 42% of homes with an EPC in Cardiff are rated band D or below (median score 70, band C), against 53% across Wales. Based on certificates lodged in the 10 years to March 2025. Source

Choosing between combi, system and regular

A combi suits a flat or a terrace with one bathroom. It heats water on demand and frees the airing cupboard. A family semi in Llanishen or Rhiwbina with two bathrooms often does better with a system boiler and an unvented cylinder, because two showers at once will overwhelm most combis.

Ask each installer to work out the heat loss of your home rather than replacing like for like. Many boilers in Cardiff are oversized, which costs you in short cycling and lower efficiency.

Scale protection

Building regulations expect scale protection on new installations where water hardness is above a set level. Cardiff's supply sits in Welsh Water's moderately hard band, so ask each installer what they plan to fit on the cold main and why. A magnetic filter on the heating return is standard practice and protects the boiler from sludge.

What a fair quote includes

The boiler, flue, magnetic filter, a chemical flush of the system, a smart or programmable controller, removal of the old unit and Building Regulations notification. Get the warranty length in writing and note that it usually depends on a yearly service.

Our new boiler cost guide gives national price ranges to check quotes against.

When the boiler has failed and money is tight

Nest, the Welsh Government scheme, can repair or replace a boiler for eligible households left without heating or hot water. Its main offer is heat pumps and insulation, so read our heating grants page for Cardiff before you commit to a new gas boiler.

Cardiff homes and what they need

Victorian bay-fronted terraces

Moving the boiler from the back kitchen into the loft or a bedroom cupboard frees space, but it adds pipework and a new flue route. Get the cost of the move listed separately.

Interwar and post-war semis in the northern suburbs

Swapping a regular boiler for a combi removes the loft tanks and cylinder. It suits smaller households; larger ones should price a system boiler too before the cylinder goes.

Modern apartments around Cardiff Bay and the centre

Flue position is the tight constraint in flats. A new boiler may need a different flue kit, and leaseholders may need the freeholder's consent for any change to the outside wall.

Areas covered

Engineers who cover Cardiff work across areas including Roath, Cathays, Canton, Pontcanna, Grangetown, Splott, Llandaff, Whitchurch, Rhiwbina and Penarth.

View Cardiff on Google Maps

Questions people in Cardiff ask

Should I put in a gas boiler or a heat pump?

If your home is well insulated and has room for an outdoor unit, get a heat pump quote as well. The Boiler Upgrade Scheme applies in Wales and pays £7,500 towards one.

Sources

Also nearby: Boiler installation in Swansea, Boiler installation in Bristol, Boiler installation in Gloucester

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