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Here’s the direct answer first. For most London homes still connected to the gas network, a gas boiler remains the most practical choice for reliable, fast heating and hot water, particularly in period properties with standard radiators. Electric boilers suit small flats with no gas connection. Heat pumps work best in well-insulated homes with larger radiators or underfloor heating, and they’re a longer-term investment rather than a direct swap.
That’s the summary. The rest of this guide explains why, because the right answer genuinely depends on your specific property, not a general rule that applies to everyone.
We’re a Gas Safe registered team carrying out boiler repair service London wide for eight years, and we get asked this question constantly, usually by someone who’s seen a heat pump grant advert or a headline about gas boilers being phased out and isn’t sure what it actually means for their house. Here’s a straight comparison, with nothing oversold in either direction.
How each system actually works
Gas boilers burn natural gas to heat water directly, delivering it almost instantly to your taps and radiators. They’re the dominant heating system across London because the gas network already reaches most properties, installation is straightforward, and the technology is extremely well understood by every engineer in the city.
Electric boilers heat water using electric elements rather than a gas flame. There’s no flue, no gas safety certificate required, and no combustion byproducts, which makes them a genuine option for flats or properties without a gas connection. They tend to suit smaller properties better than large ones, since heating water electrically at scale costs more than gas per unit of heat produced.
Heat pumps don’t generate heat by burning fuel at all. They extract latent heat from the air (or occasionally the ground) and concentrate it using a refrigeration cycle, similar in principle to a fridge working in reverse. They deliver heat at a lower temperature than a gas boiler, which means they work best alongside larger radiators or underfloor heating rather than small original radiators sized for a hotter system.
Side-by-side comparison
| Factor | Gas boiler | Electric boiler | Heat pump |
| Requires gas connection | Yes | No | No |
| Typical install complexity | Low, especially like-for-like | Low | Higher, often needs radiator upgrades |
| Space needed | Compact, wall-mounted | Compact, wall-mounted | Outdoor unit plus indoor cylinder |
| Heat-up speed | Fast | Fast | Slower, runs more continuously |
| Best suited to | Most London homes with standard radiators | Small flats, no gas supply | Well-insulated homes, larger radiators or underfloor heating |
| Maintenance familiarity | Extremely well understood by engineers | Well understood | Growing, but fewer specialists than gas |
| Noise | Minimal | Silent | Outdoor unit has audible operation |
Why gas boilers remain the practical default for most of London
London’s housing stock is dominated by Victorian and Edwardian terraces, conversions, and mansion blocks, almost all originally built around gas central heating with radiators sized for the higher flow temperatures a gas boiler produces. Swapping to a heat pump in one of these properties without addressing radiator sizing and insulation first typically means the home takes noticeably longer to heat up and may struggle to reach the same comfort level on the coldest days.
This isn’t an argument against heat pumps generally, it’s specifically about matching the system to the property as it currently stands. A gas boiler, particularly a well-maintained one, continues to be the most dependable option for homes that haven’t had significant insulation or radiator upgrades.
Where electric boilers make genuine sense
If your property has no gas supply at all, which is more common than people expect in some converted London flats and new-build developments, an electric boiler is often the simplest and most cost-effective route to reliable heating, without the retrofit work a heat pump installation usually involves. They’re also a sensible option for very small properties where hot water and heating demand is low enough that the higher running cost per unit doesn’t add up to a significant difference overall.
Where heat pumps genuinely make sense right now
Heat pumps perform best in homes that are already reasonably well insulated, have (or can accommodate) larger radiators or underfloor heating, and have outdoor space for the unit itself. New-build flats and recently renovated properties across London are increasingly suited to this, since modern building regulations already favour lower flow temperature systems. If you’re planning a renovation that includes new radiators or underfloor heating anyway, that’s the natural point to seriously consider a heat pump rather than retrofitting it onto an unmodified system later.
What we’d actually tell you if you called us
If your existing gas boiler is working and the main thing prompting you to consider a switch is a grant advert or a general sense that gas is “going away,” it’s worth knowing that no current UK policy forces you to remove a working gas boiler. There’s no urgency driven by regulation. The decision should come down to your property, your insulation, and whether you’re already planning renovation work, not a deadline that doesn’t actually exist for existing homeowners.
If your gas boiler has developed a fault, it’s very often cheaper and faster to repair than to switch systems entirely, and a proper diagnostic visit will tell you honestly which situation you’re in.
Get a straight answer for your specific property
Every property is different, and the right system depends on your insulation, radiator setup, and what you’re already planning to do with the property. Call us on 07877767776 or visit www.boilerserviceslondon.co.uk and we’ll give you an honest assessment, whether that’s a straightforward boiler repair in London for your existing system or genuine guidance on whether a switch makes sense for your property.
FAQs
For a small flat with no gas connection, an electric boiler is usually the simpler and more practical choice. If gas is already connected, a gas boiler typically remains cheaper to run for anything beyond very light hot water and heating demand.
No. You can replace a gas boiler with another gas boiler. There is no current requirement forcing homeowners to switch to a heat pump when an existing gas boiler reaches the end of its life.
Often not without some changes. Heat pumps deliver heat at a lower temperature than a gas boiler, so radiators sized for a hotter system may need to be larger, or you may need underfloor heating in some rooms, to achieve the same comfort level.
Generally no, since electricity costs more per unit of heat produced than gas in most cases. Electric boilers tend to make sense where there’s no gas connection available, rather than as a cost-saving swap for an existing gas system.
The key factors are your current insulation level, whether your radiators are adequately sized (or can be upgraded), and whether you have outdoor space for the unit. A proper survey is the only reliable way to confirm suitability rather than assuming based on property type alone.