Looking at the state of your old boiler now, do you think it will survive the winter? There’s a lot to think about when it comes to keeping your warm home during the colder months. Do you go with what you know and fit another gas boiler, or take the plunge on a heat pump? We’re not trying to steer you either way here, so consider this the honest version rather than a sales pitch.
We’ll walk through how each one actually works, what they cost to buy and run, what living with each one is actually like day to day, and roughly which suits which kind of home, whether that’s a Victorian terrace in Cardiff or a bungalow out near Cowbridge.
How each system works
A gas boiler burns gas to heat water, which then gets pushed round your radiators and, depending on how it’s plumbed in, your hot water too. It’s combustion at its core, a controlled flame doing the work, and it can get properly hot pretty quickly.
A heat pump does things completely differently. There’s no flame involved at all. Instead, it pulls heat out of the outside air, and yes, there’s usable warmth in the air even on a cold day. It uses a refrigerant cycle (think of a fridge, but running backwards) to concentrate that heat and push it into your home. No flue in the traditional sense, and it runs on electricity rather than gas.
Neither is harder to live with once it’s in. They’re just two genuinely different ways of getting heat into your radiators.
Upfront cost comparison
This is usually where people’s eyes widen a bit, so let’s just get the numbers out there. A new gas boiler, fitted, generally costs somewhere between £2,000 and £4,500, depending on the model and how straightforward the job turns out to be.
A heat pump, fully installed, typically runs from around £8,000 up to £15,000, sometimes more on a bigger or more complicated property. That’s before any grant comes off. Right now the main one is the current Boiler Upgrade Scheme grant, which knocks £7,500 off for most homes, or £9,000 if you’re off the gas grid and currently on oil or LPG. Once that’s taken off, most households end up paying somewhere between roughly £500 and £7,500, which closes the gap a fair bit, even if it doesn’t quite disappear compared with a straightforward boiler swap.
One thing worth noting. A heat pump quote can include things a boiler quote simply wouldn’t, bigger radiators or a new hot water cylinder, for example. Always check what’s actually included before comparing two figures side by side.
Running costs and efficiency
This is the bit that genuinely doesn’t have a neat one-size-fits-all answer. Heat pumps are far more efficient machines, typically getting around three units of heat out for every one unit of electricity they use. A gas boiler is close to fully efficient at turning gas into heat, but it’s burning a fuel that’s cheaper per unit than electricity to begin with.
So the real question isn’t which one’s more efficient, it’s whether that efficiency gap makes up for electricity costing several times more than gas, unit for unit. On a standard tariff, running costs between the two often land fairly close together, sometimes slightly favouring the heat pump, sometimes not, depending on your tariff, how well insulated your home is, and how the system’s been set up. Homes on an electricity tariff built around heat pumps, with cheaper off-peak rates, tend to see the clearest savings. Honestly, it’s worth a call to your energy supplier to ask about heat-pump-friendly tariffs if you’re leaning that way.
Comfort differences
This is the one that catches people out, and it’s worth knowing before you commit either way. A gas boiler heats water to somewhere between 60 and 80 degrees, so your radiators get properly hot, properly fast. Great if you like walking into a warm house within minutes of getting home.
A heat pump runs cooler, usually between 35 and 45 degrees, and rather than blasting the house warm in short bursts, it’s built to hold a steady, even temperature over a longer stretch. Plenty of people end up preferring this once they’re used to it, a home that never really cools down rather than one that swings hot and cold. Others miss that instant hit of heat a boiler gives you. Because the water’s cooler, radiators sometimes need to be bigger to put out the same heat, so a heat pump job might mean upsizing a few of them, something we’d tell you about during the survey, not halfway through the install.
Installation time and disruption
A standard boiler swap is normally done in a day, occasionally spilling into a second if access is tricky or the old system throws up a surprise.
A heat pump install is a bigger job, usually two to three days once you factor in fitting the outdoor unit, any radiator changes, and getting the controls dialled in properly. It’s not a major upheaval, but it’s worth building into your plans rather than expecting the same quick turnaround as a boiler swap.
Which is right for your home?
Think of this as a rough steer rather than a strict rule. If your home’s reasonably well insulated, already has decent radiators or room to upsize a few, and you’re not trying to keep the upfront spend as low as humanly possible, a heat pump is well worth genuine consideration, especially with the grant taking a decent chunk off the cost.
If you’re off the gas grid entirely and currently running on oil or LPG, the case tends to stack up even more, both because those fuels usually cost more to run and because the bigger grant is aimed specifically at that group. We see a lot of this out in the more rural stretches of the Vale of Glamorgan and around Bridgend.
If your home’s older, solid-walled, and hasn’t had much insulation done yet, or if keeping costs down right now matters more than anything else, a straightforward gas boiler replacement is often still the sensible move, at least for the time being. Nothing wrong with that at all. A heat pump fitted into a home that isn’t ready for it rarely works out well for anyone.
Where gas boiler policy actually stands
You may have come across mentions of a 2035 gas boiler phase-out somewhere online, and it’s worth clearing that one up, because things have moved on. That plan, which would have stopped new gas boilers being fitted in existing homes from 2035, was scrapped by the government as part of the Warm Homes Plan published in January 2026. There’s currently no legal deadline forcing you to replace a working gas boiler, and if yours does die on you, you can still fit another gas boiler like for like.
The one place things have genuinely changed is new-build homes, which now have to be fitted with low-carbon heating rather than gas as standard. That doesn’t touch existing properties, which is what most of the people calling us are actually dealing with.
This is an area that’s shifted more than once already, so if long-term planning matters to your decision, it’s worth keeping an eye on official updates rather than treating any one date as set in stone. We’re always happy to talk through where things currently stand when you get in touch, but for anything carrying legal weight, always check the latest guidance on gov.uk directly rather than taking our word, or anyone else’s, for it.
Get an honest opinion from CS Boxall
Whichever way you’re leaning, the best next move is a proper survey rather than working off an article. We’re Gas Safe registered and MCS certified, so we fit and service both gas boilers and heat pumps, and we’ve got no real reason to push you toward one over the other beyond what genuinely suits your home.
We’ve been working across Cardiff, Penarth and the Vale of Glamorgan for well over a decade now, and we’ll always give it to you straight, even if that means telling you a heat pump isn’t quite right for your place just yet. Take a look at our air source heat pump installation page or our boiler installation page to see how each works, or get in touch to speak to our heat pump specialists about a no-obligation survey.
Frequently asked questions
Is a heat pump cheaper to run than a gas boiler?
Depends on your tariff, how well insulated your home is, and how the system’s set up. On a lot of standard tariffs, running costs end up broadly similar, sometimes slightly favouring the heat pump. Homes on a heat-pump-friendly tariff tend to see the clearest savings.
Do I need to change my radiators for a heat pump?
Sometimes, not always. Because heat pumps run cooler water through the system, a few radiators might need upsizing to keep the same output. We’ll check this properly during a survey so you know exactly what your home needs before agreeing to anything.
How long do heat pumps last compared to boilers?
Both generally last somewhere between 15 and 20 years with proper annual servicing, so there’s not much between them on paper. As with most heating systems, how long it actually lasts comes down to the quality of the install and how well it’s looked after.
Can I keep my gas boiler as backup?
Some homeowners do go for a hybrid setup, keeping the old boiler alongside a new heat pump for the coldest stretches. It’s not the usual approach and adds a layer of complexity, but it’s worth chatting to us about if it’s something you’re weighing up.
Will gas boilers be banned in the UK?
Not for existing homes, no. The 2035 phase-out that used to get talked about was dropped by the government back in January 2026. You can still buy, install and replace a gas boiler like for like today. New-build homes are a different story though, they’re now required to use low-carbon heating instead of gas.