Choosing an electric boiler vs a gas boiler is mainly a choice between lower running costs and a simpler, combustion-free installation. For most homes already connected to mains gas, a modern gas boiler is currently cheaper to run. An electric boiler can make more sense in a smaller, well-insulated property, a home without mains gas, or somewhere a flue is difficult to install. The right answer depends on heat demand, hot-water use, electrical capacity and the existing system, not one headline efficiency figure.
I install both electric and gas boilers. That means my recommendation is based on what suits your home and budget, rather than on having only one type of boiler to sell.
Electric vs gas boiler comparison at a glance
This table gives the practical differences first. The prices are APL guide figures for common installations, not remote quotes. I inspect the property before confirming a fixed price because boiler output, controls, cylinders, cable capacity, flue position and pipework can all change the job.
| Factor | Electric boiler | Gas boiler |
|---|---|---|
| Running cost | Usually higher on a standard tariff. The July to September 2026 Ofgem average is 26.11p per kWh before boiler and system losses. | Usually lower where mains gas is available. The equivalent Ofgem average is 7.33p per kWh before boiler and system losses. |
| Installation cost | Straightforward installations can start around £1,800. Replacing gas with electric commonly starts around £2,500 because safe decommissioning and electrical work may be required. | A straightforward like-for-like combi replacement can start around £2,200. A larger conversion commonly starts around £3,500. |
| Boiler efficiency | Close to 100% at the point of use because there is no heat lost through a flue. This does not make electricity the cheaper fuel. | A modern condensing boiler is normally 90% or more efficient when correctly sized, controlled and operated at suitable temperatures. |
| Space and siting | Compact, quiet and no flue or gas supply is needed. A hot-water cylinder may still be necessary for greater demand. | A combi can be compact but needs a suitable flue and gas supply. System and regular boilers also need hot-water storage. |
| Expected lifespan | Plan around 10 to 15 years as a sensible comparison point. Fewer combustion components can simplify maintenance, but pumps, controls and scale still matter. | A quality boiler that is correctly installed and serviced commonly lasts around 10 to 15 years. Condition and maintenance matter more than fuel alone. |
How electric and gas boilers work
Both types can heat water for a wet central-heating system, so an electric boiler can usually work with conventional radiators and underfloor heating. The difference is how the boiler creates heat. A gas boiler burns mains gas in a sealed combustion chamber. An electric boiler passes electricity through heating elements, rather like a large-scale kettle, then circulates the heated water around the system.
A gas boiler needs a gas supply, flue, condensate route and suitable ventilation arrangements. An electric boiler has no combustion and no flue, but it needs a correctly designed electrical supply. Higher-output models can place a substantial load on the property, so I check the available supply and expected heat demand before recommending one. Choosing electric purely because the unit looks compact can lead to poor performance if that assessment is skipped.
Gas vs electric boiler running costs
Running cost is the biggest difference. Ofgem's average capped direct-debit rates for 1 July to 30 September 2026 are 26.11p per kWh for electricity and 7.33p per kWh for gas, including VAT. Electricity therefore costs about 3.6 times as much per purchased unit in this snapshot. Your regional rate and tariff may differ, and the cap is updated every three months.
Efficiency narrows that gap, but it does not remove it. At an illustrative 99% boiler efficiency, electric heat costs about 26.4p per useful kWh. At 90% boiler efficiency, gas heat costs about 8.1p per useful kWh. Those figures exclude standing charges and distribution losses, but they explain why a direct electric boiler usually costs more to run than a modern mains-gas boiler for the same heat demand.
The household calculation can still change. A home that removes its gas meter may avoid the separate gas standing charge, while solar panels and a battery may offset some electricity bought from the grid. Time-of-use tariffs can help when heat is stored at cheaper times. However, winter solar output is lower when heating demand is highest, so I would not assume solar makes a whole-house electric boiler cheap to run without modelling actual generation, storage and consumption.
Electric boiler vs gas boiler installation cost
An electric boiler can be simpler to site because it has no flue and needs no new gas connection. My guide price for a straightforward electric installation starts around £1,800. Replacing a gas appliance with electric commonly starts around £2,500 once safe gas decommissioning and the required electrical work are included. A new circuit, consumer-unit work or a supply upgrade can increase the price, so a low boiler-only quote is not a reliable project total.
For gas, a straightforward like-for-like combi replacement can start around £2,200. Changing system type, relocating the boiler, altering the flue or upgrading pipework can move the price above £3,500. I survey the existing heating system and provide a written fixed-price quote for either route. The comparison should cover the complete installation, controls and any cylinder work, not just the appliance box.
Efficiency: why 100% does not automatically mean cheaper
Electric boilers are close to 100% efficient at the point of use because almost all purchased electricity becomes heat inside the home. Modern condensing gas boilers are usually rated at 90% or above, with some energy leaving through the flue. That makes electric more efficient as an appliance, but efficiency and cost are different measurements. The much higher electricity unit price currently outweighs the smaller efficiency advantage in most mains-gas homes.
Whole-system performance also depends on correct sizing, radiator output, weather or load compensation, flow temperature, insulation and controls. An oversized boiler that cycles repeatedly can perform poorly regardless of fuel. I assess the system rather than treating the badge efficiency as a guarantee of the bill you will receive.
Space, noise and hot-water demand
Electric boilers are compact, quiet and flexible to position because there is no burner or flue. That can be useful in flats, smaller homes and properties where an acceptable gas flue route is difficult. A gas combi is also compact and provides hot water without a cylinder, but its position is constrained by gas and flue rules. Neither option should be selected on boiler dimensions alone.
Hot-water demand is often decisive. A small electric combi may suit one bathroom and modest use, but it can struggle to deliver the flow expected by a larger household. An electric boiler paired with a correctly sized cylinder can serve more demand, although the cylinder needs space and introduces storage losses. Gas combis offer strong instantaneous performance where mains water flow is suitable, while a gas system boiler and cylinder is often better for simultaneous bathrooms.
Lifespan, servicing and safety
A sensible planning range for either boiler is about 10 to 15 years, although a good installation can last longer. Electric boilers have no burner, flue or combustion gases, which removes several gas-specific checks. They still contain elements, relays, pumps, controls and safety devices that can fail, and hard water can affect components. Manufacturer maintenance and warranty conditions still apply.
Gas boilers need annual servicing to check combustion, the flue, seals, safety devices and overall condition, as well as to protect many warranties. Gas work must be completed by an appropriately qualified Gas Safe registered engineer. My registration is 660157. Whichever boiler you choose, correct sizing, clean system water and timely attention to faults usually matter more to service life than the fuel label.
When an electric boiler is the better fit
- The property is not connected to mains gas and oil or LPG is unattractive.
- It is a smaller, well-insulated home with a modest heating load.
- A safe and compliant flue route would be difficult or disproportionately expensive.
- The available electrical supply can support the required boiler output.
- Hot-water demand is modest, or there is space for a suitable cylinder.
- Solar PV, battery storage or a useful time-of-use tariff forms part of a properly calculated plan.
- Removing on-site combustion is a priority and the expected running cost is affordable.
When a gas boiler is the better fit
- The home already has a sound mains-gas connection and compatible wet heating system.
- Lower day-to-day fuel cost is the main priority under current tariffs.
- The property has a larger heat demand or more than one busy bathroom.
- There is a suitable compliant location for the boiler, flue and condensate route.
- A like-for-like replacement avoids expensive changes elsewhere in the system.
- The household wants proven high-output heating without relying on an electrical supply upgrade.
Electric boiler, heat pump or gas boiler?
An electric boiler is not a heat pump. It normally turns roughly one unit of electricity into one unit of heat. A heat pump moves heat from outside and can deliver more heat per unit of electricity, but it needs a different survey covering heat loss, emitters, outdoor space and operating temperatures. If reducing fossil-fuel use is the main objective, compare all-electric boiler costs with a properly designed heat-pump option rather than assuming the two technologies perform alike.
Electric boilers create no combustion emissions at the property. Their wider carbon impact depends on how the electricity is generated and when it is used. Gas boilers burn a fossil fuel on site. Those environmental differences matter, but they should sit alongside affordability, fabric efficiency and whether the proposed system can keep the home comfortable on a cold day.
Electric or gas boiler decision checklist
Use these questions before requesting quotes. If several answers are unknown, a home survey is more valuable than another online calculator.
- Is mains gas already connected, and would removing it eliminate a standing charge?
- What is the calculated heat loss of the property, not just its number of bedrooms?
- Can the electrical supply and consumer unit support the required electric-boiler output?
- How many showers, baths and hot-water outlets may be used at the same time?
- Is there room for a cylinder if instantaneous hot water will not meet demand?
- Can a gas boiler have a compliant flue and condensate route in the preferred position?
- What will each complete installation cost after controls, pipework and electrical work?
- What do current tariffs imply for annual running cost at the estimated heat demand?
- Will planned insulation, solar panels, battery storage or renovation change that demand?
- Would a heat pump deserve comparison before committing to direct electric heating?
My verdict as an installer of both
For a typical Kent home already on mains gas, a modern gas boiler is usually the lower-running-cost choice at current capped rates. Electric can be the more practical answer for a smaller property, an off-gas home, a difficult flue position or a carefully planned all-electric setup. I install both, so I can compare the actual system, explain the trade-offs and provide a fixed quote without steering every homeowner towards the same fuel.
Electric and gas boiler FAQs
Sources and further reading
Official guidance used to check the legal, safety or price-cap details in this article.