British Gas vs Octopus for a new boiler: only one of them fits gas boilers

Quick answer: Only one of these two fits gas boilers. British Gas installs over 100 boiler models with a 5-year parts and labour warranty. Octopus’s public heating pages sell heat pumps and biomass under the Boiler Upgrade Scheme, with no gas boiler offer at all. So the real choice is a British Gas boiler at British Gas prices, or changing heating type with the standard £7,500 behind you.

We haven’t had either company do work for us. This is based on what British Gas and Octopus publish on their own websites, on gov.uk scheme rules and on third-party review figures (checked 27 July 2026), plus the Ofgem price cap for October–December 2026 (checked September 2026). We have no commercial relationship with British Gas or Octopus Energy and receive nothing from either.

What each company actually sells

British Gas lists over 100 new boiler models from Vaillant, Worcester Bosch and Ideal. Every one gets a 5-year British Gas warranty on parts and labour, with a condition attached that the site states plainly: an annual boiler service is needed to keep it valid. Miss the service, lose the cover. The fixed price includes system water treatment and a system cleanse, waste collection and disposal, and a carbon monoxide detector and room thermostat. (britishgas.co.uk, checked 27 July 2026)

Octopus doesn’t offer a gas boiler on any of its public heating pages. Its Boiler Upgrade Scheme page covers £7,500 off an air source or ground source heat pump, £9,000 for an eligible off-grid home on oil or LPG, which is a time-limited uplift running 21 July 2026 to 31 March 2027, and £5,000 for a biomass boiler. Its typical heat pump price is £4,459 after the £7,500 grant. So if you ring Octopus wanting a combi swap, you’ll be offered a heat pump. That’s the whole conversation.

Side by side

Sources: britishgas.co.uk new boilers page; octopus.energy Boiler Upgrade Scheme and Cosy heat pump pages; Selectra supplier review pages for British Gas (updated April 2026) and Octopus (updated May 2026). All checked 27 July 2026.

Read the British Gas finance example properly

British Gas publishes a representative example for its ten-year plan: monthly payments of £32.36 on a £2,503 loan, total £3,883.20. Do the subtraction. Ten years at 9.9% adds £1,380.20 to a £2,503 boiler. That’s over half the boiler again, in interest.

The same page offers up to three years at 0% APR with no deposit. Take that instead. Carrying the payment over 36 months rather than 120 is worth more than any brand difference on this page, and it’s the one decision on the whole job that costs you nothing to get right.

British Gas doesn’t publish a headline boiler price, so treat the £2,503 in the representative example as an illustration rather than a quote. Our own modelled mid-point for a boiler replacement is £2,804 with a modelled range of £1,823 to £4,346, which you can read alongside our cost methodology and the boiler buying guide.

Running costs settle this, not installation costs

Under the Ofgem cap for 1 October to 31 December 2026, gas is 7.97p per kWh and electricity is 26.32p. Electricity costs 3.3 times as much per unit. That sounds like it ends the argument. But it doesn’t, because a boiler burns a unit to make a unit and a heat pump moves three or four.

Run the three numbers:

• A gas boiler at 90% efficiency delivers a kWh of heat for about 8.9p
• A heat pump at SCOP 3.4 (the Cosy 6 figure at 50°C flow) delivers one for about 7.7p
• The same heat pump at SCOP 2.8 (the Cosy 6 figure at 65°C flow) delivers one for about 9.4p

So the heat pump beats the boiler at 50°C and loses at 65°C. The flow temperature is a design decision made by whoever sizes your radiators. Get it in writing before you sign anything. Our glossary of heating terms explains SCOP and flow temperature if those are new to you.

One more line in the ledger. If you remove gas from the property entirely you stop paying the gas standing charge, 29.68p a day under the same cap. That’s about £108 a year whether you burn a unit or not.

Which we would pick

Boiler died in January, mains gas at the door, no appetite for building work: British Gas will do it, and a 5-year parts and labour warranty backed by a national engineer network is a real thing to own. Take the 0% finance over three years, not the 9.9% over ten, and get one quote from a local Gas Safe registered firm for the same model so you know what you’re paying for the network.

Off gas, on oil or LPG, and planning ahead: the Octopus route. With £9,000 available on eligible off-grid oil and LPG homes between 21 July 2026 and 31 March 2027, the net cost of changing heating type lands close to what a premium gas boiler costs, and you drop the gas standing charge on the way out.

On mains gas with a boiler that still works and no urgency? Neither, this year. Spend the money on insulation first. A smaller heat loss makes every later decision cheaper, and it’s the one upgrade that improves whichever system you end up with.

FAQs

Does Octopus install gas boilers at all?

Not on any of its public heating pages, which cover heat pumps and biomass boilers under the Boiler Upgrade Scheme. For a gas boiler you’ll need British Gas or a local Gas Safe registered installer.

Is British Gas more expensive than a local boiler firm?

British Gas doesn’t publish a headline price, so the only honest comparison is two written quotes for the same make and model, including the same cleanse, thermostat and warranty terms. Get both before you decide.

Can I get a grant towards a new gas boiler?

No. The Boiler Upgrade Scheme pays only towards heat pumps and biomass boilers. A gas boiler replacement gets nothing, and the 0% VAT rate that runs on heat pumps, solar, batteries and insulation until 31 March 2027 doesn’t cover gas boilers either.