Boiler Installation in Cornwall: Costs, Options & What to Expect in 2026

Do you actually need a new boiler?

Before committing to a full replacement, it's worth understanding whether a repair might suffice. As a general rule: if your boiler is under 10 years old and the repair cost is less than 50% of a new installation, repair is usually better value. If the boiler is over 15 years old, recurring faults, high fuel bills, or an F1 fault code (heat exchanger) usually signal replacement is the right call.

Signs that point clearly towards replacement include: a boiler that cycles on and off frequently without reaching temperature, yellow or orange flames (should be blue), frequent pressure drops requiring regular repressurising, and condensate pipes that freeze every winter.

Gas, oil, and LPG: which applies to you?

Cornwall's heating landscape is unusually diverse compared to most of England. Understanding which fuel type you have dictates your options:

• Mains gas — Available in St Austell town centre, Truro, Newquay, Bodmin, and larger coastal towns. If you're on gas, a straight combi or system boiler replacement is the simplest and lowest-cost option (typically £2,200–£3,500 installed).
• Oil (OFTEC) — The dominant fuel in rural Cornwall. Approximately 60–70% of rural properties heat with oil. Oil boiler replacements cost £2,500–£4,500 installed. However, the £7,500 BUS grant makes switching to a heat pump financially compelling — see below.
• LPG — Found in villages without mains gas that have an above-ground tank. LPG boiler costs are similar to oil but running costs are typically 20–30% higher than oil. LPG properties also qualify for the BUS grant if switching to a heat pump.

Around 60% of the locations we serve across St Austell, Bodmin, Truro, Fowey, and Lostwithiel are either partially or fully off the mains gas grid.

Boiler installation costs in Cornwall 2026

Installed costs vary based on fuel type, property size, and whether the flue or system components need upgrading:

• Mains gas combi replacement (like-for-like): £2,200–£3,000
• Mains gas system boiler (with cylinder): £2,800–£3,800
• Oil combi replacement (like-for-like): £2,500–£3,500
• Oil system boiler with new cylinder: £3,200–£4,500
• LPG combi replacement: £2,800–£3,800

These prices include supply, installation, commissioning, and Gas Safe / OFTEC certification. They don't include the cost of a new oil tank (if required) or any upgrades to radiators.

VAT on boiler installations is charged at the standard rate (20%) unless the installation is part of a qualifying energy efficiency upgrade, in which case a 0% rate may apply. We'll advise on this during the survey.

Best boiler brands for Cornwall homes

For gas boilers, Vaillant and Worcester Bosch consistently top reliability surveys and offer 10-year warranties with registered installers. Ideal and Baxi offer good mid-range value for like-for-like replacements.

For oil boilers, Grant (Irish manufacturer with a strong UK service network) and Worcester Bosch's oil range are our most commonly specified brands. Both offer high seasonal efficiency ratings (SEDBUK A) and have good parts availability. We carry the Vaillant ecoFIT pure and Worcester Bosch Greenstar 4000 as standard stock.

Is a heat pump a better long-term option?

For oil-heated homes, the answer is often yes — particularly with the £7,500 BUS grant available. Here's an honest comparison for a typical Cornwall rural home (4-bedroom, 120m²):

• New oil boiler: ~£3,500 installed. Running costs ~£1,800–£2,200/year (based on current oil prices). Expected lifespan: 12–15 years.
• Air source heat pump: ~£12,000–£14,000 installed before grant. After £7,500 BUS grant: ~£4,500–£6,500. Running costs ~£900–£1,400/year with a smart tariff like Octopus Cosy. Expected lifespan: 20+ years.

The heat pump payback vs. oil boiler (on total cost of ownership) is typically 7–10 years when accounting for running cost savings. Properties with existing wet underfloor heating or radiators sized to 55°C flow temperature are particularly well-suited.

If you're unsure which route suits your property, our free survey includes an honest assessment of both options. See our heat pump vs gas boiler comparison for the full analysis.

The £7,500 BUS grant explained

The Boiler Upgrade Scheme provides a £7,500 upfront grant towards the installed cost of an air source heat pump. Key eligibility criteria:

• You must currently heat with a fossil fuel (oil, gas, LPG, electric storage heaters, or solid fuel)
• The property must have a valid EPC with no outstanding cavity wall or loft insulation recommendations
• The installer must be MCS-certified (we are)
• Grants must be applied for before installation begins — you cannot claim retrospectively

The grant is applied directly against the installation cost — you don't receive the money; CCS claims it on your behalf and deducts it from your invoice. Full details at our BUS grant guide.

What installation involves

A standard boiler replacement takes one to two days. The process: isolate the existing system, drain down, remove the old boiler, install the new unit, connect to existing pipework, fit a new flue if required, commission and test, then provide all certification documentation.

If we're upgrading from a regular (heat-only) boiler to a combi, additional work may be required to remove the existing hot water cylinder and cold water tank in the loft. We include a full scope of works in every quotation so there are no surprises.

For oil boiler replacements, OFTEC certification is issued at completion — this is required by your insurer and is the equivalent of Gas Safe registration for oil appliances.

Get a boiler quote for your Cornwall home

CCS Heating & Renewables installs and services boilers across Cornwall, including St Austell, Bodmin, Truro, Newquay, Wadebridge, Fowey, and Lostwithiel. We carry out a free survey, provide a fixed-price quote, and — if you qualify — handle the BUS grant application on your behalf.

Book your free survey or call 01726 861234.