Heat Pumps vs Gas Boilers: Which Is Better?

We are a heat pump installer, so you might expect us to say heat pumps win every time. We are not going to do that. The honest answer is: it depends on your home, your budget, and what matters most to you. Here is a fair comparison.

Running Costs

This is where heat pumps have a clear advantage. A heat pump is roughly 300% efficient — it produces about 3kW of heat for every 1kW of electricity it uses. A gas boiler is around 90% efficient at best.

In real money, for a typical three-bedroom house:

System	Typical Annual Cost
Air source heat pump	£800–£1,100
Gas boiler	£1,400–£1,800

That is a saving of roughly £500–£700 a year. Over 20 years, that is £10,000–£14,000 — which more than covers the higher upfront cost, especially after the grant.

One caveat: these figures assume a well-designed system and a reasonably insulated home. If a heat pump is poorly installed or undersized, running costs can be higher than expected. Design and installation quality matter enormously.

Upfront Cost

Gas boilers are cheaper to install. A new gas boiler typically costs £2,500–£4,500 installed. A heat pump installation costs £10,000–£16,000 before the grant.

After the £7,500 Boiler Upgrade Scheme grant and 0% VAT, a heat pump typically costs £2,500–£8,500. That is closer to boiler territory, though still more expensive in most cases.

If budget is very tight and you need a heating system replaced urgently, a gas boiler can be the more practical option right now. We say this as a heat pump installer — we would rather be honest than push you into something that does not work for your situation.

Efficiency

Heat pump: ~300% efficient (COP of 3.0 or higher). For every unit of electricity in, you get three units of heat out. This is possible because a heat pump does not generate heat — it moves it from the outside air into your home.

Gas boiler: ~90% efficient. A modern condensing boiler converts about 90% of the gas it burns into heat. The other 10% is lost.

There is no contest here. Heat pumps are fundamentally more efficient.

Lifespan and Maintenance

A gas boiler typically lasts 12–15 years. It needs an annual gas safety check (legally required if you are a landlord, strongly recommended for everyone else). Parts wear out. Heat exchangers fail. Repairs become more frequent as the boiler ages.

A heat pump typically lasts 20–25 years. It needs an annual service, but there is no gas safety check, no combustion analysis, no flue inspection. There are fewer moving parts and no risk of carbon monoxide.

Installation Disruption

A boiler swap is usually a one-day job. The engineer removes the old boiler, fits the new one, and you have heating by the evening.

A heat pump installation takes 2–5 days. There is more work involved — an outdoor unit needs installing, pipework may need modifying, and a hot water cylinder may need fitting. If you are coming from a combi boiler, there is no existing cylinder, so that adds work.

It is more disruptive. We plan around you to minimise the impact, but it is worth being realistic about this.

Noise

Gas boilers make some noise — the ignition click, the pump, the fan. But they are inside the house and most people tune it out.

Heat pumps have an outdoor unit that produces a low hum, typically around 40–45dB. That is about the same as a fridge. You can hear it if you stand next to it, but from inside the house or from a neighbour's garden, it is barely noticeable. Read more in our post on heat pump noise levels.

Environmental Impact

A gas boiler burns fossil fuel. Every unit of heat it produces comes with carbon emissions. A typical gas boiler produces around 2–3 tonnes of CO2 per year.

A heat pump runs on electricity. As the grid gets greener (and it is getting greener every year), a heat pump's carbon footprint shrinks. Even on today's grid mix, a heat pump produces roughly half the carbon of a gas boiler. Pair it with solar panels and the figure drops further still.

If reducing your environmental impact matters to you, a heat pump is the clear winner.

When a Gas Boiler Might Still Make Sense

We believe in giving honest advice, so here are the situations where a gas boiler could still be the better choice:

• Very tight budget. If you genuinely cannot afford even the after-grant cost of a heat pump and need heating now, a gas boiler is cheaper upfront.
• Very poorly insulated home with no plans to improve it. Heat pumps work best in reasonably insulated homes. If your home has no loft insulation, single glazing, and solid walls with no insulation, a heat pump will work harder and cost more to run. Insulation improvements first would make a big difference.
• No outdoor space. If you genuinely have nowhere to put an outdoor unit (very rare, but it does happen), a heat pump is not possible.

The Bottom Line

For most homes, a heat pump is the better long-term investment. Lower running costs, longer lifespan, no carbon emissions, and a £7,500 grant to bring the upfront cost down. But it is not right for every situation, and we would rather tell you that honestly than sell you something that does not suit your home.

The best way to find out is to talk to us. We will visit your home, look at your specific situation, and give you a straight recommendation — even if that recommendation is "stick with gas for now."