Should You Replace Boiler With a Heat Pump – Full Guide

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The UK is gradually moving away from traditional fossil fuels as the main source of energy used in the home, and one of the biggest targets is oil and gas boilers. This choice of heating system has several huge disadvantages, such as high carbon emissions, escalating energy bills, and a dependence on the world economy which can negatively impact on fuel prices.

The answer as to what the UK Government proposes will replace many oil and gas boilers is air-source heat pumps and ground-source heat pumps. These pumps generate heat locally, independent of energy supply lines, and as a result, are immune to price fluctuations, or any other inconvenience traditional heating methods bring.

But should you replace a boiler with a heat pump? Keep reading to find out or check out our boiler v heat pump guide.

What is a Heat Pump?

A heat pump is a green energy heating system designed to replace gas boilers as the UK’s standard heating system. It essentially pulls in heat from the natural elements of either water, air or the ground, meaning it’s infinitely replenishable with little in the way of maintenance being required.

Heat pumps generate heat by using an agent called a refrigerant. The refrigerant has a low boiling point, meaning that it will boil at much colder temperatures than, say, water. 

When the source heat pump system circulates the refrigerant so that it makes contact with the ground, air, or water, the refrigerant pulls in heat and begins to boil. It turns into a gas and is compressed to raise the heat. This heat is then released into your home, and the refrigerant goes from gas back to liquid – meaning there’s no need to replenish the refrigerant.

Why replace a boiler with a heat pump?

The following will be a list of reasons as to the benefits that come when you replace a gas boiler or an oil boiler with a heat pump.

Lower Energy Bills

Lowering your energy bills permanently is the foremost reason why you should consider switching to a heat pump.

  • Energy Efficient – The energy efficiency of a heat pump is unmatched when it comes to heat generation. This is because it primarily uses electricity to power the heat generation, but very small amounts of it. You’re not burning gas or oil, but rather you’re simply combusting the very air you breathe in daily through an ingenious method offered by heat pump technology. It is so efficient that different models are graded on their “Coefficient of Performance”, which uses whole numbers to grade how energy efficient they are. The whole numbers represent the heat-to-energy ratio. So, for example, a COP of 4 would represent that the heat pump is capable of generating four units of heat for every unit of electricity it requires.
  • Price Hike Protection – A gas or oil boiler relies not only on your country’s economic circumstances but also on the places which trade those resources such as oil and gas. Considering how little say an individual resident of the country has on these matters, it’s safe to say that how much your gas boiler costs you monthly is out of your control. That is not the case with heat pumps, as they draw from both the air or ground, so are not at risk of price fluctuations due to world economic events.

Control Your Carbon Footprint

The UK Government has shown that it is serious about the introduction of low-carbon heating systems. The Paris Agreement of 2015 saw a meeting of 195 parties representing countries across the world, putting to paper their commitment to reducing the carbon emissions of their respective countries. They are bound to this treaty via the threat of ever-increasing fines for failing to hit targets.

  • Green Future – A gas boiler combusts gas, and an oil boiler combusts oil. Both of these are fossil fuels, meaning they are finite and becoming rarer as time goes on, and emit a great deal of carbon. This worsens global warming, which is having many detrimental effects on the planet. A heat pump eliminates this, ensuring you can live a greener life.
  • Complete Ownership – A heat pump generates heat differently from oil and gas boilers. The heat pump doesn’t draw or generate heat energy from a finite resource, instead, it draws from the very environment through an air-source heat pump, ground-source heat pump or water heat pump. 

Improved Quality of Life

Fact of the matter is, there are several things about a heat pump that, outside of the money you save, makes heat pump technology genuinely better than having a boiler.

  • Cooling and Heating System – Heat pumps are not used solely to heat your home. All heat pumps come with a cooling system alongside the heating. This means you’re able to control exactly how warm or cool your home is through one device – your heat pump.
  • Better Heating – Whilst a typical gas boiler will do a decent job at heating your home, it does so by unleashing a burst of heat energy. Heat pumps differ in this regard, as instead, they let out a consistent stream of gentle warmth that you have full control over. This can create a much cosier environment.
  • SMART Technology – The beauty of heat pumps is that they are a modern technology. Which, in today’s age, means it’s highly convenient. From your very phone you can control your heat pump remotely in advanced ways, such as manually setting temperatures or scheduling when the heat pump should be in heating and cooling cycles.

The Government is Incentivising You (for now)

As we’ve already stated, the UK Government wants you to replace a gas boiler with a heat pump, as well as installing other energy efficiency measures. It has proven this by offering several incentives for the transition.

  • Grants – The UK decided to put the onus on footing a good portion of the bill on the top energy companies in the country. If you were to replace a gas boiler with a heat pump in England or Wales, for example, then the boiler upgrade scheme would cater directly to you, providing you meet eligibility criteria. It offers £7,500 towards air source and ground source heat pumps, and £5,000 off the cost of biomass boilers.
  • Low-Interest Loans – To incentivise households to get an air pump and make it more affordable, the government is offering low-interest loans in some cases as a means of encouraging the uptake of low-carbon heating systems.
  • Tax Breaks – Another common way of encouraging people to make the transition from oil/gas boilers to heat pumps is by reducing the tax they pay on installations. The UK government has reduced the VAT payable on heat pump installation to 0% until March 2027, down from the already reduced rate of 5%.

Is my home suitable for a heat pump replacement?

Despite all the great benefits of a heat pump, the fact of the matter is, there are both suitability and compatibility requirements for several areas of your home. The reasoning is as follows:

  • Energy Efficiency Barrier- We mentioned that your old gas boiler heats your home through large bursts of energy. These bursts of energy consumption sometimes hide a serious problem for a lot of homes – that of minimal insulation. Insulation refers to the ability to retain heat and not let it escape through the building’s walls and windows. Whilst it’s a problem for all heating systems, it’s especially a problem for heat pumps. That’s because a heat pump will deliver heat through a consistent flow. That consistent flow will hardly be felt before it’s lost without insulation, unlike the burst of a gas-condensing boiler.
  • Heat Delivery Device – Heat pump technology generates heat, but it doesn’t deliver it in quite the same way a gas boiler does. While the heat is dispersed through a device such as a radiator, due to the weaker heat distribution, it requires a larger surface area to deliver. This could come in the form of a larger radiator, or perhaps an even more modern system – underfloor heating.
  • Space Requirements – Heat pumps work by connecting to outside sources. This means you’ll be required to make space enough for them to interact. What space you’ll need exactly depends on the type of heat pump.
    • Air Source Heat Pump – An air source heat pump looks indistinguishable from a normal air conditioning unit – 1 to 2 metres tall and wide. It requires clearance and easy access for any maintenance jobs, of which there should be few. This is not at all a large concern, but bear in mind that it’s slightly noisier than an air conditioning unit. As a result, it may be a good idea to keep the unit away from bedrooms or any other room that requires comfort.
    • Ground Source Heat Pump – Ground source heat pumps require a lot more space. For one, the ground source heat pump unit will require housing within the home, and is about the size of a boiler, or bigger if you’re installing with a hot water cylinder. Furthermore, the heat pump requires an “underground loop”, which is essentially what’s gathering the heat. There are two types of loops.
      • Vertical Loop – Requires deep boreholes.
      • Horizontal Loop – Requires surface area within the garden for trenches.

What if my home is not suitable for a heat pump system?

A ground source heat pump system takes up a lot of space, whilst an air source heat pump takes up much less. Fact of the matter is though, not all homes can accommodate either. However, there are ways of using your existing oil or gas boiler with a heat pump rather than outright replacement.

Hybrid System

A hybrid system uses a boiler with a heat pump to create a majority green energy system. It does this by installing a much smaller air source heat pump unit to generate most of your passive warmth throughout much of the year, with the boiler existing only as backup during especially trying cold weather, or perhaps purely for the hot water cylinder.

Although this sounds like a lesser heat pump setup, the fact is this is a much better solution than no heat pumps.

  • Reduced Upfront Cost – A hybrid heating system is cheaper than either a ground source heat pump or air source heat pump. With a boiler, and existing pipework, you can install a hybrid system for between £3,000 – £8,000.
  • Lowered Space Requirements – Air source heat pumps naturally take up less space than a ground source heat pump, but a hybrid’s air component is even smaller than otherwise necessary.
  • Insulation Mitigation – The effects of lowered insulation will be mitigated when your home’s heat pump has a boiler backing it up. This frees up your budget to invest in further home improvements, such as cavity wall insulation or double glazing.


We hope this post has achieved its objective of outlining the great advantages of making the transition to heat pumps, a long-term energy generation system that is green for the planet, and lighter on your wallet in the long-term..

If you want competitive heat installation prices from top class heating installers, enquire with us today. We will have the top heat pump companies contact you in a no-obligation consultation. Take advantage of government incentives and take control of your heating bills today. 

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Ollie Creevy
Ollie has been writing content online about home improvements for over 3 years. With a real interest and in-depth knowledge of heat pumps and ECO home improvement measures you can use to save on your energy bills. Ollie also keeps up to date with all the Government grants available for you to take advantage of like ECO4 and the Boiler Upgrade Scheme.