Heat Pump Running Costs vs Fossil Fuels – Honest UK Guide

Is a Heat Pump Cheaper to Run Than Gas or Oil in the UK?

If you're trying to work out whether a heat pump will cost more or less to run than your gas boiler, you're going to find a lot of contradictory information online. Some people swear their bills dropped significantly after switching. Others say their heat pump costs more than gas ever did. The frustrating thing is that both groups are telling the truth and the reason for that difference has almost nothing to do with which brand of heat pump they have.

Electricity in the UK costs more per unit than gas. That's the starting point for any honest comparison, and it's also why heat pump running costs are so misunderstood. The way a heat pump competes isn't by using cheap fuel it's by using far less of it. Understanding that distinction is what separates a useful answer from a misleading one.

How Heat Pumps Are Fundamentally Different From Boilers

A gas boiler burns fuel to create heat. It's efficient at doing that a modern condensing boiler converts around 90% of the gas it burns into usable warmth but it can never produce more heat than the energy it consumes. A heat pump works on a completely different principle. Rather than generating heat, it moves it extracting thermal energy from the outdoor air and transferring it inside. Because of this, it can deliver significantly more heat energy than the electricity it uses to run.

This ratio is measured as the Coefficient of Performance, or COP. A well-designed heat pump running at the right conditions will achieve a COP of between 3 and 4 meaning for every unit of electricity it consumes, it delivers three to four units of heat. That efficiency advantage is what makes heat pump running costs competitive despite the higher unit price of electricity. When the system is working as it should, it uses so much less energy per unit of heat that the running costs come out ahead of, or at least comparable to, gas.

Why Some Heat Pumps Cost Less to Run and Others Don't

This is where the real answer lives, and it's the part most comparison guides skip over. A heat pump achieves its best efficiency when it operates at low flow temperatures typically between 35°C and 50°C. At those temperatures, the COP stays high, electricity consumption stays low, and the running cost case stacks up well against gas. The system needs the right conditions to deliver that: a properly calculated heat loss for the property, radiators sized to deliver adequate heat output at those lower temperatures, and a system designed with weather compensation so the flow temperature adjusts automatically with the outdoor conditions.

When those things aren't in place, the heat pump has to compensate by running hotter. At 60°C or above, the COP drops toward 2 or lower, and the electricity cost advantage evaporates. This is the most common cause of the high-bill complaints you read about not a faulty heat pump, but a poorly designed system pushing the heat pump to work harder than it needs to. In many of these cases, the underlying issue can be identified and corrected without a physical engineer visit. Remote heat pump fault diagnosis and system reviews have resolved exactly this kind of problem for homeowners across the UK, and it's worth knowing that not every heat pump problem requires an expensive callout to fix.

Comparing Heat Pump Running Costs to Gas

At 2026 UK energy prices, electricity sits at around 24–25p per kWh under the Ofgem price cap, while gas is roughly 6–7p per kWh. That's a ratio of about 3.5:1. For a heat pump to match gas on running costs, it needs to achieve a COP of at least 3.5 which a well-designed system running at low flow temperatures can and does reach in real-world conditions. If the system is achieving a COP of 3 or above consistently, you're in a broadly comparable position to gas, with additional benefits in lower carbon emissions and less exposure to gas price volatility. If you're seeing a COP closer to 2, your running costs will be higher than gas and that points to a system design or setup issue worth investigating rather than a reason to dismiss heat pumps entirely. Our guide on how to reduce heat pump electricity bills covers the most common causes of high running costs and what can realistically be done about them.

Heat Pump Running Costs vs Oil and LPG

Oil and LPG are almost always more expensive per unit than mains gas, which means the comparison against heat pumps tends to land more favourably. In properties that currently run on oil or LPG typically rural homes not connected to the gas grid a well-designed heat pump system will often be cheaper to run outright, not just comparable. The gap between oil and heat pump running costs widens further when oil prices spike, which they do unpredictably. Switching to a heat pump in these properties also provides more stable, predictable energy costs, which many homeowners find valuable in itself. If you want to understand whether a heat pump is likely to be worth it for your specific property, our full guide on are heat pumps worth it in the UK works through the real numbers in detail.

The Upfront Cost Picture

Heat pumps cost more to install than a replacement boiler. A typical air source heat pump installation in a UK home ranges from £8,000 to £15,000 before any grant funding, depending on property size, system complexity, and whether radiator upgrades are needed. The Boiler Upgrade Scheme currently provides a £7,500 government grant, which brings the net cost for most installations into a much more manageable range. Whether the upfront cost makes financial sense depends on the running cost saving you achieve and that comes back to system design. A system designed correctly from the start, with accurate heat loss calculations and properly sized radiators, is significantly more likely to deliver the running cost savings that make the investment worthwhile. If you're considering a new installation, it's worth reading our overview of what size heat pump your house needs before committing to any quotes.

How Heat Pumps Feel Day-to-Day

One thing that affects how people perceive running costs is simply how different heat pumps feel compared to boilers. A gas boiler fires up, heats radiators to 65–75°C, and switches off. You feel the heat quickly, and the system cycles on and off throughout the day. A heat pump runs at lower temperatures radiators feel warm rather than hot and operates more continuously, maintaining a steady temperature rather than reheating from cold. This means the electricity meter runs more consistently rather than in spikes. The total cost might be similar or lower, but it can feel psychologically different if you're used to a boiler. Homeowners who adjust their expectations and run the system as it's designed to be run continuously at a steady setpoint rather than switching it on and off like a boiler typically report much better experiences. Our article on why heat pump radiators feel lukewarm explains this difference in detail and helps distinguish normal operation from a genuine performance problem.

Why You See Contradictory Information Online

The reason the internet is full of conflicting heat pump experiences comes down to one thing: the quality of the installation. Two identical heat pumps in two different houses, installed by two different companies, can produce completely different running costs. One homeowner is paying less than they did for gas. Another is paying significantly more. The heat pump is the same. The difference is in whether the system was correctly designed for the property it was installed in whether someone did a proper heat loss calculation, checked the radiators, set up weather compensation, and handed the system over with clear guidance on how to use it. If your heat pump is currently costing more than expected, the answer is almost always in the system setup rather than the hardware itself. A diagnostic review of how your system is operating is usually the most efficient way to find out what needs to change and in most cases, it doesn't require an engineer on site to identify the problem.

The Honest Answer

A heat pump can be cheaper to run than gas in a well-designed system. It will often beat oil and LPG even in average conditions. But it can also cost more than gas if the system is running inefficiently at higher temperatures due to poor design or incorrect setup. The heat pump itself is rarely the problem. The system around it the design, the radiators, the controls, the commissioning is what determines which side of that line you end up on. If you're planning an installation, getting the design reviewed properly before anything goes in is the single most effective thing you can do to protect your running costs. If you're already installed and the bills aren't what you expected, a proper look at why your heat pump is using too much electricity is a logical starting point.

Thinking About Installing a Heat Pump?

If you want to understand what a heat pump will actually cost to run in your property before you commit, that needs a proper assessment not a generic calculator. Our Pre-Installation Design and Heat Loss Review looks at your property's heat demand, what temperatures the system will need to run at, and whether your existing radiators are suitable, so you have a realistic picture of running costs before anything is installed.

Already Installed and Bills Higher Than Expected?

If your running costs are higher than you expected, it's almost always down to how the system is operating rather than the heat pump itself. Our Fix My Heat Pump Diagnostic Call and Action Plan reviews your flow temperatures, system behaviour, and where efficiency is being lost and in most cases can identify the cause and a clear path to fixing it without requiring a physical visit to your property.