Heat Pumps

In this guide we investigate, score and rank the ethical and environmental record of 11 ground source and air source heat pump brands.

We also look at the use of global warming refrigerant gases and give our Best Buys and recommended buys.

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This is a product guide from Ethical Consumer, the UK's leading alternative consumer organisation. Since 1989 we've been researching and recording the social and environmental records of companies, and making the results available to you in a simple format.

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What to buy

What to look for when buying a heat pump:

  • Does it use a natural refrigerant? Heat pumps use refrigerants. Natural ones like ammonia, isobutane and CO2 are all deemed as having close to zero global warming potential in comparison to standard HFC refrigerants.

Best Buys

LG scored top in almost all of our policy categories including getting our best rating for sourcing of conflict minerals.

Recommended Buys

Although these brands scored poorly on our policy ratings such as environmental reporting and conflict minerals, they  scored the best across all the categories and were top of the table:

Air source heat pumps: Baxi Ambiflo, Glow-worm and Vaillant.

Ground source heat pumps: Vaillant.

Hybrid heat pumps: Glow-worm, Vaillant.

What not to buy

What to avoid when buying a heat pump:

  • Does it use HFC as its refrigerant gas? HFCs are the most common refrigerants used in heat pumps. HFC has a global warming potential of over 1,600 more than CO2.

Companies to avoid

Worcester Bosch and Mitsubishi score poorly across the board on our score table.

For example, Bosch played a significant role in VW's diesel emissions scandal by supplying a control unit that was used to cheat laboratory tests.

The Mitsubishi Corp is involved in the production of nuclear fuel, including uranium mining in Australia, and in oil and gas exploration It also owns Princes, which has been criticised for its unsustainable fishing of tuna.

  • Worcester
  • Mitsubishi Electric

Score table

Updated live from our research database

← Swipe left / right to view table contents →
Brand Score(out of 20) Ratings Categories Positive Scores

Baxi Ambiflow air source heating

Company Profile: Baxi Heating UK Ltd

Ideal heat pumps

Company Profile: Ideal Boilers

Keston air source heat pumps

Company Profile: Ideal Boilers

Glow-worm Clearly heat pumps

Company Profile: Glow Worm

Vaillant heat pumps

Company Profile: Vaillant UK

LG heat pumps

Company Profile: LG Electronics Inc

Viessmann heat pumps

Company Profile: Viessmann UK

Worcester Greensource air to air heat pumps

Company Profile: Worcester Heat Systems

Panasonic heat pumps

Company Profile: Panasonic Corporation

Mitsubishi Electric Ecodan heat pumps

Company Profile: Mitsubishi Electric Corporation

Samsung heat pumps

Company Profile: Samsung Electronics Co Ltd

What is most important to you?

Product sustainability

Our Analysis

Heat pumps

What are heat pumps?

There are two types of heat pump available to the home-owner, air source and ground source heat pumps.

Heat pumps are basically fridges in reverse. They use electricity to move outside heat – either from the air or from the ground – into your house. They are about three times more efficient than a normal electric bar heater, and can produce hot water as well as heating homes.

Heat pumps have not widely caught on in the UK, but they are common in many other countries, particularly Sweden, Switzerland and France.

They produce less heat than conventional boilers, so they’re only suitable for well-insulated houses.

As their names suggest air source heat pumps extract heat stored in the outdoor air and ground source heat pumps extract heat which is stored in the ground.

Generally, they are more efficient when heating things to a lower temperature, so they work best with large heating surfaces – which means either having underfloor heating or large radiators.

Air source is not always feasible at lower temperatures, especially since the times when you’re most likely to need them, i.e. In the morning and evening, the air temperature will be at its lowest. A higher efficiency can generally be achieved from a ground source heat pump as the average temperature underground is higher than the average air temperature.

Ground-source, air-source or hybrid?

Heat pumps come in different types. Air-source are less efficient than ground-source but are cheaper, easier to install and suitable for a wider variety of properties. You also get water-source heat pumps, but they aren’t used at a domestic level.

With air-source you just need an outside wall, so they can be installed on almost all properties, including flats. The pump itself is about the size of a fridge. All the companies make air source heat pumps.

Ground-source come in two types: horizontal or vertical. The horizontal ones require an outside area twice the size of the house. The vertical ones only require room to dig a borehole and access for the drilling machinery, but they are more expensive than the horizontal ones. Also, only some areas have suitable geology for a ground source heat pump, as they don’t work well in areas with sandy soils. On the score table, Vaillant, Ideal, Worcester, Viessmann and Mitsubishi Electric make ground-source heat pumps.

There are also hybrid systems, which combine a heat pump with a small backup gas boiler. For many people, this may be the easiest option.Vaillant and Glow-Worm make hybrid systems.

How good are they?

If they are running on renewable-powered electricity, heat pumps have greenhouse gas emissions of close to zero.

However, using the current general electricity grid mix, the carbon benefits of heat pumps in the UK are debated. Some people say that they are substantially better than gas boilers, while some people say there is no real benefit at all. The thing is, it all depends on what efficiency the heat pump achieves, and many in the UK are performing poorly. However, the best performers are doing much better than average, and so it is widely believed that the poor efficiencies have just been caused by bad installation.

Another reason to have faith in the potential performance of heat pumps is that in other countries they tend to manage much better efficiencies, and that should theoretically be replicable here.

Score table highlights

  • All of the companies, apart from LG, got our worst rating for management of workers’ rights in supply chains.
  • Seven of them – Remeha (Baxi), Groupe Atlantic, Panasonic, Samsung, Mitsusbishi Electric, Viessmann and Robert Bosch (Worcester) – had inadequate policies whilst Vaillant said nothing at all about workers’ rights.
  • Most companies did better on reporting about their environmental impacts, with LG and Samsung scoring best in this category.

Conflict minerals policies

We rated all the companies for their policy on the sourcing of conflict minerals – tin, tantalum, tungsten and gold – because they use them in their electrical components. There is a risk that revenues generated from the sale of these minerals is being used to fuel conflict in a number of countries in central Africa, most notably the Democratic Republic of Congo.

Most of the companies get a worst rating. LG got a best rating and Panasonic scored a middle rating.

Ideal, Mitsubishi Electric and Samsung received our worst rating for not having adequate policies but they at least did better than the following companies which did not even mention conflict minerals – Viessmann, Vaillant, Baxi, Worcester Bosch.

Refrigerant gases

Heat pumps use refrigerants, and the most common are HFCs, such as R407 which has a global warming potential (GWP) of over 1,600 more than CO2. Any leakage can easily turn the heat pump from a friend of the climate into its worst enemy. However, it is generally considered possible to keep leakage levels low enough that this is not too much of an issue.

CO2 was one of the most widely used refrigerants alongside ammonia in the early 20th century and is now having a renaissance. As the Global Warming Potential values for HFC refrigerants are nearly two thousand times higher than for CO2, leakage of CO2 gas from a refrigeration system is consequently nearly two thousand times less damaging to the environment than the release of any HFC gas.

Plus CO2 is a more efficient refrigerant than HFC.

In terms of environmental impact, natural refrigerants are all deemed as having close to zero global warming potential in comparison to standard HFC refrigerants. Other natural refrigerants are:

√  R170 – Ethane     √  R290 – Propane     √  R600a – Isobutane     √  R717 – Ammonia     √  R744 – CO2

In 2011, Peter Bartley of CHB Sustainability had this to say about refrigerants:

"Heat pumps are designed as tightly sealed systems in order to minimise leaks; however there is always a chance of a leak of a chemical which can pose a significant contributory factor towards climate change (around 20% of the climate change effect of refrigeration is due to refrigerant leaks and the other 80% due to the energy used).

There are now alternative refrigerants which have a much lower, or in some cases no contribution towards global warming. However, these chemicals can pose their own risks in terms of safety and environmental impact. Common low GWP alternatives are ammonia, hydrocarbons (petrochemicals such as propane, isobutane and butane) and CO2. However, ammonia is very toxic and flammable. Hydocarbons are highly flammable and can contribute to pollution, and so ironically CO2 looks to have a future as the ‘green’ refrigerant alternative to HFCs!"

What do heat pumps cost?

Heat pumps are rather expensive. Air source are in the region of £6,000-£10,000 for the whole system including installation. Ground source are about £9,000-£16,000. Gas boilers cost between £500 and £2500. See our guide to gas condensing boilers.

Unfortunately, while heat pumps save energy, electricity is a much more expensive fuel than gas, so their running costs may not be much lower than a gas boiler.

You can get some help with the cost. Heat pumps are one of the technologies now supported under the Renewable Heat Incentive (RHI). The RHI gives regular payments for the first seven years of running your pump, at the rate of 10.49p per kWh heat generated for air-source, and 20.46p for ground-source (from 1st April 2018).

This will help you pay back the capital cost, although you may not make all of it back.

If you aren’t on the gas grid, a heat pump is a great heating option, as in this instance you may well save money as well.

If you are on the gas grid, they are less financially attractive. But if you have some spare cash and you care about the climate, there is good reason to consider one.

There is an urgent need to help the industry here get going. If we were all using heat pumps there would still be the issue of decarbonising the electricity they run on, but it would, nonetheless, be a massive step towards decarbonising our heating. And if consumers support heat pumps, they can be expected to get better with time.

The efficiency measure for heat pumps

The Coefficient of Performance (CoP) is the unit by which the performance of heat pumps is measured. Basically, it measures the amount of heat produced, as compared to the amount of electrical energy required to produce it. The less electricity required, the higher the CoP, and the more efficient the heat pump.

So for example, at a CoP of 3, you put in 1 unit of electricity and you get out 3 units of heat.

Ground source heat pumps tried and tested

Testimonials from two readers in 2011.

It is now five years since Ulrike had ‘earth heating’ installed in her farm in Germany. They dug one mile of plastic coils into the ground (her partner and son did this work, borrowing machinery from a friend). The liquid in the coils transports the ‘heat’ from under ground to the family’s big 800 litre water tank. A pump keeps the liquid flowing and the ‘heat’ from the transport liquid is passed into the water that goes into the house (for the central heating).

The water tank also takes the heat from the solar cells on the roof. The family had already installed the tank when they built a solar thermal heating system 15 years ago together with a wind generator (which has recently broken down due to a storm).

Ulrike says she’s found that the the pump which keeps the liquid flowing is the most expensive aspect of ground source heating. It takes 24 kw of energy, which costs about 300 Euro a month, making it quite uneconomical. This is despite it providing heating and hot water for the three households that reside on Ulrike’s farm.
Overall their ground source heating system cost 30,000 Euros, and that was without the costs of installation. Plus, the family already had some equipment because they’d previously had the solar thermal system installed.

This winter and the one before were problematic as temperatures where Ulrike lives in Germany reached -15C, and the equipment struggled. Factoring in the costs and hiccups with the equipment, Ulrike said she would be undecided if asked whether she would install this technology again.

Ulrike Best

In September 2009, Peter Griffiths had a ground source heat pump installed at his rural home in Shropshire. The decision to invest in a ground source heat pump was made when his oil boiler needed replacing.

At first Pete considered a bio-mass boiler, however, concerns over the reliability and sourcing of fuel lead to the decision to install a ground source heat pump instead.

Pete went with a recommended provider which used their own certified installers and engineers. While everything from the initial decision on investing in a heat pump to the actual installation of the heat pump went smoothly, Pete explained that the work was very disruptive and, as with all building projects, took twice as long as expected and cost more then expected.

The heat pump which was installed used a ‘horizontal closed loop field’, which meant that roughly half an acre had to be dug up. In Pete’s case, this involved going into the next door neighbour’s land. Given the amount of land needed for a horizontal heat pump it may not be very practical for people living in urban areas.

Overall Pete had a very positive experience with the installation of the heat pump. Despite the disruption and under-budgeting, he felt that the pay back on it and the efficiency of the heat pump made up for it. Pete estimated that £10,000 had been paid for the installation of the heat pump, which included some work on his central heating system. In terms of energy bills, Pete thought £500 per year was being saved, however, his electricity usage had been increased. As the life span was estimated at 20 years, he was happy he would make back his money.

The investment has been further boosted by the fact that Pete will qualify (retrospectively) for the Renewable Heat Initiative (RHI) through which he will receive just over £1000 per year in grants. This is more than enough to pay for his energy bills per year.

Pete Griffiths

Company behind the brand

The Worcester brand is owned by German company Robert Bosch, a private company with €73 billion sales in 2016. Bosch is an engineering and electronics multinational which has US Department of Defense contracts.

A percentage of the profits made by Robert Bosch is donated to charities and good causes by the Robert Bosch Foundation, a non-profit charitable trust which owns 92% of its share capital. The foundation does not have voting rights; it uses the share dividend it receives for charitable purposes in areas such as research, education, and social welfare. Since its founding in 1964, the Robert Bosch Foundation has spent £757 million on funding in these areas.

Robert Bosch’s ‘Mobility Solutions’ business sector, one of the world’s biggest automotive suppliers, accounts for 60% of total sales.

Bosch has agreed to pay $327.5 million to resolve allegations in the US that it played a significant role in Volkswagen’s diesel emissions scandal. The civil settlement, which includes cash payments to some owners of VW diesel vehicles caught up in the scandal, resolves claims against Bosch in the US.

VW admitted, in September 2015, that the German carmaker had equipped US diesel vehicles with illegal software, dubbed a ‘defeat device’, which served to understate emissions of harmful nitrogen oxides in official tests.

Bosch acknowledged shortly after the scandal broke that it supplied a component – known as electronic diesel control unit 17 – that VW used so its vehicles could cheat in laboratory tests. But it has not been established that Bosch knowingly programmed the component to facilitate VW’s cheating.

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If you want to find out detailed information about a company and more about its ethical rating, then click on a brand name in the Score table. 

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