How Much Does a New Boiler Cost in 2026?

A complete boiler installation isn't just the boiler. A fair quote should always cover the following items as line-items or be explicitly listed as included:

• The boiler itself, sized correctly to your property's heat loss (not just like-for-like)
• A full system flush (powerflush on older systems, chemical flush on newer ones) — sludge in old radiators will void manufacturer warranties
• A magnetic filter (Magnaclean, ADEY) fitted on the return — required for most 10-year warranties
• A scale reducer on the cold mains in hard-water areas (most of Northamptonshire qualifies)
• Updated flue and condensate routing to current building regs
• Gas pipe re-sizing if the existing 15mm run is undersized for the new boiler
• System inhibitor dosed correctly post-flush (X100 or equivalent)
• Building Regulations notification via Gas Safe Building Notification Scheme
• Manufacturer warranty registration on the day of install
• 12-month workmanship guarantee from the installer

The honest variation between a lower-end and higher-end install comes from real differences:

• Boiler relocation — moving from airing cupboard to kitchen adds a fixed-price uplift for pipework and flue
• Cylinder removal on a regular-to-combi conversion — additional labour, quoted as a separate line
• Loft tank removal — fixed-price line to drain, dismantle, remove and tip
• Gas pipe upgrade from 15mm to 22mm — priced on run length and access
• Flue routing complexity — vertical or rear-discharge flues for listed properties add a separate fixed-price line
• Power flush on a heavily-sludged system — fixed-price add-on if needed before the install
• Smart controls upgrade (Hive, Tado, Worcester Comfort+) — fixed-price add-on if fitted at install
• Unvented cylinder on system installs — separate fixed-price line for quality stainless steel plus G3 commissioning

Boiler-only RRP (before install) gives a sense of the brand-tier difference. As of May 2026 on common 30kW combi models:

• Worcester Bosch Greenstar 30i — top-tier trade pricing. Premium build, 10-year warranty via accredited installers, market leader in our area.
• Vaillant ecoTEC plus 832 — top-tier trade pricing. German-engineered, 10-year warranty via Vaillant Advance installers.
• Ideal Logic Max C30 — mid-tier trade pricing. Solid mid-range, 10-year warranty available, parts widely stocked.
• Baxi 830 Combi — entry-tier trade pricing. Reliable budget option, 7–10 year warranty depending on installer status.
• Glow-worm Energy 30c — entry-tier trade pricing. Vaillant-owned, sister product, 7-year warranty standard.

See our breakdown of which type to pick before brand: combi vs system vs regular boilers.