Green Services Direct

We need to ditch fossil fuel boilers to cut carbon emissions and tackle climate change.

Gas boilers are one of the biggest carbon culprits contributing to 14% of emissions – about the same as the cars we drive. Heat pumps are a greener way of heating our homes. Unlike gas or oil boilers, they warm our homes without warming the planet. But can heat pumps cut energy bills, too?  Soaring global energy prices mean millions of households are struggling to keep their homes warm in colder weather. Here we check out the pros and cons of air source heat pumps (ASHPs).

What are heat pumps?

ASHPs take heat found in the air outside and pump it into your home. An outside unit absorbs the air at a low temperature into a fluid which passes through a heat exchanger to raise its temperature and then warm your home via radiators or underfloor heating. Heat pumps can also heat water in a hot water cylinder for hot taps, showers and baths.

A heat pump is powered by electricity rather than gas or oil. Because the  heat output is greater than the energy input, they are said to be energy efficient. For every 1kWh of electricity put in,  you might get 3.5kWh of heat out, which is an impressive efficiency of 350%, according to Octopus Energy.  Heat pumps can create four times as much heat with the same amount of power as even the best gas boiler, says the green energy supplier.

Advantages:

There are many advantages to installing a heat pump: -

• Low carbon footprint – Unlike a gas or oil boiler, a heat pump produces little or no carbon emissions when operating, so they are often better for the planet. Heat pumps are powered by electricity but it’s possible to pair them with solar panels or renewable/green energy tariff for clean electricity and they are extremely energy efficient.
  In a typical household over half of the fuel bills are spent on heating and hot water. It’s possible to save 2.6 tonnes of greenhouse gas emissions from your yearly total by swapping your gas boiler with a heat pump, according to the Energy Savings Trust. That’s a massive 40% reduction in the average footprint. If you currently have an oil boiler, the carbon savings are even higher at 4 tonnes per year.
• Lower bills  - when properly installed heat pumps can cut home  heating costs, especially compared with off-grid fuels such as oil, electric or propane heating. It costs about £1,049 per year to run a heat pump, according to Octopus Energy (November 2022). On a standard tariff, you would typically save £187 a year on average with a heat pump compared to a modern gas boiler with a 90% efficiency. On a smart tariff, you could save more by scheduling the pump to run during off-peak periods. In future, green levies imposed on electricity bills are likely to be shifted to gas bills, so the savings should increase.  
• Eligible for Boiler Upgrade Scheme – heat pumps vary in price but most cost between £12,000 to £15,000, according to Evergreen Energy. Homeowners who choose to switch now are eligible for a £5,000 grant under the Boiler Upgrade Scheme (BUS). So, the amount typically paid is between £7,000 and £10,000. Ministers have vowed to work with industry to halve the cost of heat pumps by 2025 – a target Octopus Energy believes can be met.
• Pumps can be used for heating and cooling – The UK had its hottest summer on record in 2022 with temperatures climbing to 40°C for the first time. Global heating means our summers are likely to get even hotter in future. Air source heat pumps can be used for heating in winter and cooling in summer, so are adaptable for climate change. Check with the supplier if a unit can be used for both heating and cooling purposes.
• Can be used for heating and hot water – Providing it has been sized and installed correctly, a heat pump can produce enough heat for both space heating and hot water. However, you may need to replace your hot water tank with one that is designed for working with a heat pump and water at lower temperatures. Boilers heat water up to around 70-80°C whereas heat pumps used for hot water may only be efficient up to 55°C.  If there’s a demand for both hot water and space heating at the same time, the heat pump will assume that hot water is urgent and leave your space heating until the hot water cylinder reaches the desired temperatures, warns Evergreen Energy.
• Easy to install – installing a heat pump usually takes between two to five days depending on any complications that may occur during the installation process, says Greenmatch, a guide to renewable energy. The work shouldn’t be too disruptive as part of the installation is done outside your home. Domestic heat pumps don’t usually require planning permission but it’s always best to check with your local authority.
  To be sure the units and wiring are set up properly, it’s essential to hire a licensed electrician and installer with appropriate experience. Look for an accredited Microgeneration Certification Scheme (MCS) installer. A poorly installed pump may use a lot more electricity, leading to bigger bills.
• Low maintenance – Typically heat pumps are low maintenance. There are, however, a few things you need to do to ensure optimal performance, such as keeping the pump clean, wiping down the coils, removing stray leaves, checking air pressures and replacing filters. More complex technical tasks should only by done by a registered installer. It is recommended your system is serviced by an air source heat pump engineer once a year.
• Long lifespan – with proper maintenance, modern heat pumps can last for up to 25 years.
• No fuel storage needed – No fuel storage is required for heat pumps because the fuel used is the outside air.  By contrast oil-fuelled boilers require an oil tank which take up space in your garden.

Disadvantages

While there are many advantages to heat pumps, there are a few downsides which need to be considered, too.

• Home must be well insulated already - To get the most out of air source heat pumps you need to have an airtight, well-insulated home. The kit is less suitable for older, draughty homes as heat can escape from windows, doors or through walls. However, this is true for all heating systems. Houses with a low EPC (energy performance certificate) rating below C will require a larger heat pump and this can push the price up.
• Extra spending to install underfloor heating or bigger radiators – Installation costs can be higher if you require radiator upgrades or new underfloor heating. Because heat pumps operate at a lower temperature compared to gas and oil boilers hooked up to radiators, they need a larger heat emitting surface to deliver a cosy level of heating.  ASHPs work best when paired with underfloor heating or big radiators.
• Lower efficiency below O reduced efficiency in winter – While heat pumps can work when the mercury drops below -15°C, they lose efficiency below O°C. This is because the technology relies exclusively on outside air. By comparison ground source heat pumps have pipes buried beneath the ground at a more stable temperature, so are less affected by colder weather.
• Lower savings compared to mains gas A-rated boilers - If you have an ultra-efficient modern gas boiler, then the financial savings from switching to a heat pump aren’t likely to be significant. But heat pumps are a crucial tool to tackle climate change. To achieve net zero, millions of heat pumps will need to be installed in the UK, so you can expect to see more low carbon grants to encourage people to make the switch.
• Heat pumps operating noise – heat pumps can be a bit noisy when running, reaching 40 to 60 decibels, similar to dishwashers or moderate rainfall. But noise levels will vary with the type of pump and manufacturer. Some heat pumps are quieter than fossil fuel boilers. Companies are continually striving to improve the technology, including reducing the noise. 
• High initial cost - pumps are significantly more expensive than gas boilers, which typically cost between £1,500 and £3,500. So, getting a heat pump is only an option for the better-off. More government action is needed to make heat pumps as cheap and easy as possible for everyone to install, says Greenpeace.

Is an air source heat pump right for you?

Heat pumps are kinder to the planet and a key weapon in combating climate change. To reap the full benefits and achieve lower bills, you will need to have an airtight, well-insulated home. Finding the right installer is also very important to ensure the kit works optimally. A home assessment visit is usually free of charge.

Heat pumps are the future. Ministers have set out plans to roll out 600,000 heat pumps per year by 2028. New gas boilers are set to be banned from 2035 to achieve net zero. No one will be forced to scrap their working existing boilers as the future ban only applies to new installations.