The day my ancient gas boiler finally died was both a disaster and a blessing in disguise. Water was pooling across my kitchen floor, the plumber was shaking his head with that expression that screams “this is going to be expensive,” and it was, naturally, the coldest week Bristol had seen in three years. Perfect timing.
“You could replace it with another combi boiler,” said Dave the plumber, who’d been maintaining my temperamental heating system for years with increasingly creative fixes. “But honestly, love, have you thought about a heat pump? Your place would be perfect for it.” Four hours and approximately 47 open browser tabs later, I was deep into what my friends now jokingly call my “heat pump era.” And let me tell you—it’s changed everything about how I think about home energy.
Now, I realize that heating systems aren’t exactly riveting dinner party conversation for most people. Mention air source heat pumps at a social gathering and watch everyone suddenly remember they need another drink. But stick with me here, because this technology is genuinely revolutionary in terms of both performance and environmental impact. And I promise I’ll keep the technical jargon to the absolute minimum necessary to understand why these systems are so special.
So what exactly is a heat pump? At its simplest, it’s a device that moves heat from one place to another rather than generating heat directly. Think of it like a refrigerator working in reverse—instead of removing heat from inside the fridge and expelling it into your kitchen, a heat pump extracts heat from the outside air (or ground, or water) and brings it into your home. The magical part is that this process works even when it’s freezing outside because there’s still thermal energy present in air that’s well below zero degrees.
The first time Dave explained this to me, I was deeply skeptical. “So you’re telling me this thing can extract heat from freezing air? That sounds like perpetual motion nonsense,” I said, crossing my arms defensively. Dave, to his credit, didn’t roll his eyes (though I’m sure he wanted to). Instead, he asked if my fridge made ice. When I nodded, he said, “Your fridge can make water freeze even though your kitchen is 20 degrees. A heat pump is just that process running backwards.”
Something clicked in my brain at that moment. Of course! It’s not creating energy from nothing—it’s moving existing heat energy from one place to another using a relatively small amount of electricity to power the transfer. This is why heat pumps can achieve efficiencies of 300-400%—meaning for every unit of electricity used, they can generate 3-4 units of heat energy. A gas boiler, by comparison, is lucky to be 95% efficient.
After that initial conversation with Dave, I went into full research mode. My poor housemate Theo came home one evening to find the living room floor covered with printouts of heat pump specifications, efficiency curves, and installation diagrams. “Is this… normal?” he asked, carefully stepping between papers to reach the kitchen. “For me? Absolutely,” I replied without looking up from a particularly fascinating graph about coefficient of performance at various temperatures.
There are actually three main types of heat pumps, though most UK homes will only consider two of them. Air source heat pumps extract heat from the outside air and are the most common residential option. They look a bit like air conditioning units mounted on an exterior wall. Ground source heat pumps extract heat from beneath the ground via pipes buried in your garden, while water source heat pumps (the least common for obvious reasons) extract heat from a body of water like a lake or river.
For my terraced Victorian house with its postage stamp garden, an air source heat pump was the only realistic option. Ground source systems generally need significant outdoor space for the ground loop, and despite my attempts to convince the Bristol city council that the harbor would make an excellent heat source for my home, a water system wasn’t happening either.
Once I’d settled on an air source heat pump, the real learning began. I discovered there are two main varieties—air-to-air systems that blow warm air directly into your home (similar to traditional air conditioning but in reverse), and air-to-water systems that heat water for radiators, underfloor heating, or hot water tanks. Since my home already had radiators, the air-to-water option made the most sense, though it would require some modifications.
One major thing to understand about heat pumps is that they work most efficiently when producing lower temperature heat over longer periods, compared to gas boilers that blast very hot water through your system in short bursts. This means they work beautifully with underfloor heating or oversized radiators, but might struggle with standard UK radiator systems designed for high-temperature water. When I explained this to Theo, his face fell. “So we need to rip up the floors too?” he asked, already mentally packing his bags.
“Not necessarily,” I assured him, waving a particularly helpful case study I’d found. “We can replace some radiators with larger ones, and the system can still work with our existing setup—it just might not be quite as efficient as a purpose-built system.” He looked relieved but still eyed my research pile warily.
The next hurdle was finding knowledgeable installers, which proved to be its own challenge. Heat pumps might be standard in Sweden and Switzerland, but in the UK, they’re still relatively specialized. I contacted five different heating companies before finding one where the person on the phone didn’t respond with, “You want to what now?” when I mentioned heat pumps.
The company I eventually went with, GreenHome Solutions, sent an engineer named Raj who spent nearly three hours assessing my house—measuring radiators, checking insulation, examining the electrical supply, and asking detailed questions about our heating patterns. This was already a dramatically different experience from when my gas boiler was installed years earlier, which had involved about 20 minutes of measuring and a lot of guesswork.
Raj explained that properly sizing a heat pump is crucial to its performance. Undersized systems won’t heat effectively on the coldest days, while oversized ones will cycle on and off too frequently, reducing efficiency and lifespan. He performed a detailed heat loss calculation for each room, considering everything from window sizes to ceiling heights to wall construction. My inner data nerd was thoroughly impressed.
There were some surprises along the way. I learned that my electricity supply needed upgrading to handle the additional load, and that my hot water tank was woefully inadequate for a heat pump system. These were extra costs I hadn’t initially factored in. There’s a tendency in environmental circles to focus solely on the heat pump unit itself when discussing prices, but the reality is that many UK homes need additional modifications to make these systems work optimally.
Installation day arrived in early September, thankfully before the heating season kicked in properly. The process took four days—one for the electrical upgrades, two for the heat pump installation itself, and one for commissioning and testing the system. It was disruptive but not the renovation nightmare I’d feared. The outdoor unit was mounted on brackets on the back wall of my house, connected to an indoor unit in what was previously a storage cupboard. The new hot water tank replaced my old one, and five of my radiators were swapped for larger models.
The moment of truth came when they switched everything on for the first time. Instead of the familiar roar and clunk of my gas boiler firing up, there was just… a gentle humming sound from the outdoor unit. Inside, absolutely nothing to be heard. I actually asked if it was working, which amused Raj greatly. “Go feel the radiators,” he suggested. Sure enough, they were warming up—slowly but steadily.
And this was my first real adjustment to heat pump life. With a gas boiler, radiators get screaming hot very quickly, then cool down until the next cycle. With the heat pump, the radiators stayed at a more moderate temperature but remained warm consistently. It’s a different kind of heat—more even, less intense but more constant. The first few weeks, I kept touching the radiators expecting them to be hotter, but once I adjusted my expectations, I realized the house was actually more comfortable than before, with fewer cold spots and less temperature fluctuation.
The system came with a smart control panel that displays energy usage in real-time, which has turned me into something of a heat pump optimization fanatic. I’ve experimented with different settings and schedules to find the sweet spot between comfort and efficiency. The most surprising discovery was that it’s actually more efficient to keep the system running at a constant lower temperature than to turn it off completely when we’re out and then crank it up when we return—the opposite of what was most efficient with our gas boiler.
Winter provided the real test, of course. We had a cold snap in January where temperatures hovered around -4°C for nearly a week. Friends with heat pumps had warned me this would be the challenging period, but our system performed admirably. The house stayed at a comfortable 19.5°C, though the pump was working harder than usual—you could hear the fan speed increase on the outdoor unit, and our electricity usage noticeably increased. Still, we remained warm and comfortable, which was the true measure of success.
The financial aspect has been interesting to track. My electricity bill has certainly increased—roughly by about £30-40 per month during winter. However, my gas bill has disappeared entirely (I switched to an induction cooktop as well, going fully electric). The net result is that I’m spending slightly less overall on energy than I was with my old gas system, though the difference isn’t dramatic. The real financial benefit will come over time as gas prices continue to rise faster than electricity, and as electricity continues to get greener with more renewables in the mix.
I’ve also learned that how you use a heat pump makes an enormous difference to running costs. I’ve developed what Theo calls my “heat pump rules”—like keeping doors closed between rooms, using the programmable schedule properly, and monitoring external temperatures to make manual adjustments when necessary. The system is smart, but it still benefits from a knowledgeable user. I’ve become so attuned to my heat pump’s behavior that I can tell when the defrost cycle is running by a slight change in the sound it makes, which Theo finds both impressive and slightly concerning.
As for performance, I’m genuinely delighted. The house stays at an even, comfortable temperature with none of the dramatic hot-and-cold cycles we experienced with the gas boiler. The hot water is perfectly adequate for our needs, though I did have to adjust to the fact that the tank heats up on a schedule rather than on-demand like my old combi boiler. We have plenty of hot water as long as we remember the system’s patterns—no more impromptu hour-long showers after the tank has been depleted!
Of course, it hasn’t all been smooth sailing. There was a nail-biting week in November when the system developed an error code I didn’t understand, and I was convinced I’d made a terrible expensive mistake. It turned out to be a simple sensor issue that the installer fixed in about 20 minutes, but it highlighted how few people really understand these systems yet, even some heating engineers. I had called three emergency plumbers before finding one who was confident working with heat pumps.
The environmental benefits have been the most gratifying aspect. Based on the energy monitoring I’ve set up (yes, I am that person with energy monitors on everything), I’ve reduced my home’s carbon emissions by approximately 75% compared to the gas boiler. That figure will continue to improve as the UK grid gets greener. There’s something deeply satisfying about knowing my home’s warmth isn’t directly contributing to climate change—especially during those blissful moments when my electricity monitor shows my home running on solar and wind power from the grid.
Since my “conversion,” I’ve become something of a heat pump evangelist—much to the amusement of my friends. “Oh no, she’s going to talk about coefficient of performance again,” my friend Ruth whispered loudly at a recent dinner party when someone innocently mentioned their heating bills. But I’ve also become a resource for others considering the switch, and five of my friends have now installed heat pumps after consulting with me about my experience.
If you’re considering a heat pump, my biggest advice is to work with specialists who really understand these systems, not general heating engineers who’ve done a weekend course. The technology isn’t new globally—it’s been standard in many countries for decades—but it is still building momentum in the UK, and expertise varies widely. Also, be prepared for some adjustments in how you think about heating. These aren’t gas boilers with a green paintjob; they’re a fundamentally different technology with different strengths and operational patterns.
The other night, as Bristol dipped into a frosty evening, I sat in my warm living room thinking about the journey from that flooded kitchen floor to my quietly efficient heat pump. Dave the plumber stopped by last week to pick up some tools he’d left behind months ago and asked how I was getting on with the new system. “I’m in a long-term relationship with my heat pump,” I told him, “and it’s going surprisingly well.” He laughed and said I should get out more, which is probably fair advice. But when you’ve found a home heating system that’s comfortable, cost-effective, and dramatically better for the planet—well, that’s a relationship worth nurturing, isn’t it?
