Gas vs electric boiler UK: Which suits your London home?

Gas vs electric boiler UK comes down to your connections, heating demand and total costs. A direct electric boiler turns nearly all the electricity it uses into heat at home, but mains gas usually costs less per unit. For a London property, check your tariff, electrical supply and hot-water needs before comparing installation quotes.

That choice can look different in a gas-connected family home and a flat without mains gas. Even two similar flats may need different hot-water arrangements. The price on a boiler alone won’t tell you what it’ll cost to fit or run in your property.

If your current boiler has failed, it’s tempting to choose the quickest replacement. A few checks now can prevent an expensive mismatch between the new system and your home.

Gas vs electric boiler UK: What’s the real difference?

Both systems can supply central heating and hot water, but they make heat in different ways. A gas boiler burns gas to heat water. A direct electric boiler uses electricity to heat water, without burning fuel or needing a flue for combustion.

EDF describes direct electric boilers as converting 99–100% of the electricity they use into heat at the property. Industry guidance puts modern condensing gas boilers at around 90–94% efficiency. Those figures describe the boiler, not the cost of buying its fuel.

An electric boiler isn’t a heat pump. A direct electric boiler delivers about one unit of heat for each unit of electricity it uses. A heat pump can deliver several units of heat per unit of electricity, depending on the system and home.

Start by checking what’s already there. Do you have a mains gas connection? Is there space for the hot-water arrangement you need? How many showers or taps might be used together? A compact unit may appeal in a London flat, but its size alone won’t tell you whether it can meet your hot-water demand.

Electric boiler vs gas boiler running costs: Which costs less?

Mains gas usually costs less to run than direct electric heating, even though the electric boiler is more efficient at the property. The reason is the price you pay for each unit of fuel.

Why doesn’t a more efficient electric boiler mean a lower bill?

Efficiency tells you how much purchased energy becomes useful heat. Your bill also depends on what each kWh costs. To compare like for like:

1. Estimate the annual heat your home needs.
2. Divide that demand by each boiler’s efficiency to estimate fuel use.
3. Multiply each result by the relevant unit rate on your latest tariff.
4. Account for any standing charge that would change if you added or removed a fuel connection.

Here’s an illustration, rather than an October 2026 price forecast. A 2026 industry comparison uses 12,000 kWh of annual heat demand and July–September assumptions of 6p/kWh for gas and 24p/kWh for electricity. At 90% gas-boiler efficiency, that works out to about £800 for gas. At effectively 100% direct-electric efficiency, it’s about £2,880 for electricity. These calculated examples exclude standing charges and installation costs.

Those older rates shouldn’t be treated as today’s tariff. Use the gas and electricity unit rates on your current bills, along with your own usage, before deciding.

An overnight tariff may help if your setup can store heat or hot water for later use. It won’t make daytime radiator heating cheap by itself. Solar panels may offset some electricity use, but their output won’t necessarily match the times you need heating and hot water.

Cost note: All figures above are illustrative, not a London installation quote or a current tariff. For property-specific costs, ask InstaGasWorks for a quote.

What should you check before installation in London?

Get the property checked before you compare final prices. The existing connections and any upgrade work can make a substantial difference to the installation.

For an electric boiler installation in London, ask a qualified electrician to assess the incoming supply, consumer unit and wiring. They should also consider the electrical load when other appliances run at the same time. A boiler that meets your heating needs still has to work safely with the supply available to your flat or house.

For a gas boiler replacement in London, ask a Gas Safe registered engineer to check the gas pipework, flue, condensate route and heating system. A straightforward swap and a job needing changes to those parts shouldn’t be priced as though they’re identical. You can see what’s involved in our boiler installation service.

Hot water deserves its own conversation. Tell the installer how many bathrooms you have and whether people regularly use showers at the same time. Ask whether the proposed boiler can meet that demand or whether the design needs stored hot water. Then check where any cylinder would go, particularly if storage space is tight.

There are upkeep and safety differences too. Gas boilers need servicing, and any fuel-burning appliance makes carbon monoxide precautions relevant. Direct electric boilers have no on-site combustion, though their electrical installation still needs proper assessment and maintenance. If you’re keeping a gas boiler while you decide, a boiler service can help you understand its present condition.

Ask for an itemised quote showing the boiler, associated work and any proposed upgrades. That makes it easier to compare a gas replacement with a switch to electric on equal terms.

Which boiler makes sense for your home?

Your existing connection and hot-water demand should narrow the options before you choose a model. There’s no universal winner for every London property.

• Gas-connected family home: Start with a suitable gas replacement if lower running costs are your priority. Check whether the proposed setup can meet busy morning hot-water demand, and compare the full fitted price.
• Smaller flat without mains gas: An electric boiler avoids adding a gas connection and combustion flue. Check its likely running cost, available electrical capacity and hot-water performance before committing.
• Landlord replacing an existing system: Confirm the property’s heating and hot-water needs, then compare written scopes of work. Ask the installer to explain any changes needed to the existing connections and system.

If cutting carbon is a priority, compare a heat pump separately. It uses electricity differently from a direct electric boiler and can deliver several units of heat for each unit it consumes. Actual performance depends on the home and installation. Check current grant eligibility for your property rather than assuming support applies.

Likewise, don’t assume you must remove a working gas boiler because of a future ban. Check the rules in force when you’re ready to replace it. If the problem is a fault rather than a planned upgrade, establish whether a boiler repair is appropriate before pricing a complete replacement.

Your next step before choosing a boiler

Compare written quotes against the same heating and hot-water requirements. Give each installer your current tariff, details of your existing system and an honest picture of how your household uses hot water. Ask what they’ve checked and which electrical, gas or heating-system upgrades are included.

Look at the fitted cost alongside a running-cost calculation using your own rates. Then choose the system that suits your property, rather than the boiler with the most appealing headline price.

Getting a quote for your London home

If you’re weighing up a gas replacement or need your existing system assessed, we can help you check the practical options. Contact InstaGasWorks with your property details and what you need from your heating and hot water.