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Last updated: 26th December, 2022


Heat Pumps vs Modern Gas Boilers

Heat Pumps vs Modern Gas Boilers

Key takeaways

  • Gas boilers are often cheaper to run than heat pumps due to gas costing less than electricity as a fuel.
  • Heat pumps although efficient, have high initial costs.
  • Sufficient insulation is often required to redeem the maximum benefits of a heat pump.

In times of eye-watering energy prices and home heating bills, some debate which type of home heating instrument is most prudent, and most likely to save you money!

What Is A Heat Pump?

A heat pump transfers captured heat from the air outside to the inside of a property, this is then used to fuel the property’s central or underfloor heating (in some cases provide hot running water also).

Air Source Heat Pumps

An air source heat pump works by absorbing heat energy from the outside air into a fluid. The fluid is then passed through a heat exchanger and into a heat pump, this raises the temperature and then transfers the resultant heat into water.

Ground Source Heat Pumps

Ground source heat pumps work by sourcing heat from water in underground pipes (either long or coiled in trenches), which is then pumped to a heat exchanger. The cool water is mixed with antifreeze and passes through the heat exchanger, transferring the heat to the refrigerant, which continues to flow around the compressor circuit.

What Is A Gas Boiler?

A gas boiler is exactly what it says on the tin, a boiler system that heats gas in order to warm your home. 

The gas initially enters a boiler via the mains or an LPG bottle, the resulting hot water is then fed through the central heating system and can also provide a steady stream of hot water to outlets such as baths etc.

System Boilers

A system boiler links with a hot water storage cylinder to provide a home with central heating and hot water. It does this by taking cold water directly from the mains (instead of a separate feed tank) and heating it via an internal heat exchanger, this transfers gas energy to water. The hot water is then moved to the hot water cylinder for storage.

Unlike some regular boilers, such as oil or heat only boilers, that use bulky external components, with a system boiler the majority of components are integrated within the appliance. 

The only external part is the aforementioned hot water storage cylinder; This is a much smaller unit than some of the other hot water storage tank systems used by regular boilers, these tend to eat up loft space.

Combi Boilers

Combi (combination) boilers also link a home’s central heating system and water heating, however they are a single unit, with all components integrated within the boiler. 

The combi signals a sensor upon hot water demand, then takes water directly from the mains and the heat exchanger heats it for distribution to water outlets. This means there's no accompanying cylinder or hot water tank.

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Advantages of Both Heat Pumps & Gas Boilers

Heat Pump Pros

Modern Gas Boiler Pros

  • Potential savings - Heat pumps have generated a lot of buzz due to their potential to generate long term savings for prospective buyers. Heat pumps are extremely efficient in the production of heat energy, meaning a reduction in heating bills, saving prospective buyers what could turn out to be a significant amount of money each year.

  • Very efficient - Modern gas boilers are extremely efficient with most having an ErP classification of A with an energy efficiency percentage in the 90s. Upgrading an older, antiquated boiler to a new efficient combi, could save a homeowner in the region of £400 a year (per Energy Savings Trust) 

  • Reduces carbon emissions - The efficiency of a heat pump’s conversion rate and the fact it does not burn a fuel to operate, lowers a household's carbon emissions. This not only helps the planet, but also increases the safety of the home’s occupants.

  • Cheap to run - Gas is one of the cheapest types of fuel available, ensuring low running costs for modern, efficient combi boilers. This is especially beneficial in these times of unprecedented energy prices.

  • Long lifespan - On average the lifespan of a heat pump installation is around 15 years, some can however last up to 50 years!

  • Abundant - modern combi and system boilers are extremely popular in the UK, meaning their parts are easily replaced should an issue occur.

  • Can provide cooling air - When it’s hot outside, certain heat pumps are actually capable of reversing their operational process to perform like an air conditioning unit.

  • Easy to install - modern gas boilers are a relatively easy install for a trained engineer, between 1-2 days is the average time for a new gas boiler, offering minimal disruption and property upheaval 

  • Government help initiatives - The government introduced the boiler upgrade scheme. This £450 million initiative comes as part of the Heat and Buildings Strategy that offers a £6,000 reduction of the supply and installation of a ground source (£5000 for air source) heat pump for property owners in England and Wales.

  • Low unit cost - modern gas boilers are comparatively cheap per unit, especially when compared to some heat pumps, with some models costing up to 20 times less!

Disadvantages of Both Heat Pumps & Gas Boilers

Heat Pump Cons

Gas Boiler Cons

  • High initial system cost  - Heat pumps demand a very high initial purchase price with some units costing upwards of £45,000! This can negate the idea of savings offered by installing a heat pump for many people.

  • No cooling function - Gas boilers don’t have a cooling or air conditioning modality or setting

  • Electricity cost - Electricity, as mentioned, is one of the most costly types of fuel available, especially when compared to gas.

  • Not the most environmentally friendly - Gas boilers rely on the combustion of carbon based fuel, even though gas boilers have made great green strides, they are still not carbon neutral

  • Not entirely carbon neutral - Despite being reliant upon electricity to function, heat pumps are not totally carbon neutral, this is because the process of producing the electricity can be quite a carbon intensive task.

  • Servicing - Gas fuelled boilers can require a yearly inspection, known as servicing, not a legal requirement but an encouraged proactive measure.

  • Not every property is suited for heat pumps - Some properties don’t have sufficient insulation to be an ideal heat pump location. Without considerable insulation, the heat generated from a pump would be lost. Loft and cavity wall insulation can bump up the cost of a heat pump installation considerably.

Which Should You Choose?

With these considerations, a heat pump when deployed in the right setting can provide a myriad of benefits for its owner, however, also may not be suitable or advantageous for every home. 

Despite the confusion regarding the 2025 new build gas ban, there is no actual legal onus to replace your gas boiler or preventative measures to stop you getting a modern and efficient gas boiler installed.

This could mean a new gas boiler may be the more viable option to provide satisfactory heating for your property.

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Stephen Day profile photo
Article by
Stephen Day | Co-founder
Gas Safe registered and FGAS certified engineer with over 20 years experience in the heating and cooling industry.