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To reduce carbon emissions from home heating, we need to shift away from gas and oil boilers towards low-carbon technologies such as heat pumps. Heat pumps may seem like relatively novel technologies to the British market (unlike Scandinavia where they have been used for decades) so with the expertise and help of the Climate Change Transformation Board's Decarbonisation Advisor, Dave Sowden and the Manx Utilities team behind the Heat Pump Trial here on the Isle of Man, we've compiled a list of the most frequently asked questions we receive: 

How much does an ASHP cost? 

The UK’s Boiler Upgrade Scheme gives a median cost of a retrofit ASHP at £13,000 (including installation and warranty). The scheme is suitable for the able-to-pay sector who tend to liver in larger homes. 

In Isle of Man homes, Manx Utilities installations have cost between £11-15,000, which has risen in recent times due to recent price increases and supplier demand. This includes a 10 year service package and an extended 7 year manufacturer warranty.  
It is widely acknowledged that once the market becomes more competitive and demand increases, prices will fall. The UK government aims to reduce the costs of installing a heat pump by at least 25% to 50% by 2025.  In fact, Octopus Energy in the UK announced last month a new Cosy 6 Heat Pump system for the same price as the UK Boiler Upgrade Scheme - i.e free to the homeowner.

Why should I switch? 

A heat pump installation may have a larger financial outlay but they use far less electricity to heat your home because they are very efficient. A heat pump installation is also more methodical than a fossil fuel boiler installation and includes a complete heat loss assessment.  

A gas or oil boiler can easily mask the fact that it's not operating efficiently (with the consequence of higher bills, but still able to provide sufficient heat due to their ability to operate – albeit very inefficiently – at high temperatures), whereas a heat pump sometimes can't adequately heat the home if it's not correctly specified. 

Operational costs are also lower for heat pumps, with savings between £551 - £789 annually using Isle of Man energy prices.  Greenhouse gas emissions can be up to 82% less compared to gas and 88% less compared to oil as found in new research. 

How efficient are they? 

An air source heat pump can transfer 300% - 400% more energy than it consumes, comparatively a modern, condensing gas boiler which operates at a typical efficiency of 84%. Ground source heat pumps can be even more efficient.  

To get the best out of your heating system, as a customer you should receive a clear explanation to understand differences of a heat pump system and shown how to use the controls.  

They perform best when they heat homes gradually with gentle fluctuations in temperature. It is often more efficient for a heat pump to remain ‘on’, allowing its control system to optimise its performance, rather than the conventional habit of switching a boiler off during times of the day when the property is unoccupied. Maintaining a more regular temperature can provide more comfort for the household - something which ASHP owners will testify to.  

Most systems have the capability for the homeowner to monitor usage and efficiency using SMART devices. 

will I save money on fuel bills? 

A properly designed air source heat pump installation is a much more efficient heating system and can save you money on energy bills straight away. Relative to current gas and electricity prices, a properly specified and correctly installed heat pump can save customers £551 - £789 annually on fuel bills. 

Over its lifetime, you can save £9,246 compared to a gas boiler and £144 compared to an oil boiler as prices return to long term trends in 2035 and heat pump efficiencies increase.  See the Isle of Man Heat Pump study.

Old looking Air Source Heat Pump

Are they reliable? They are still new to the market and haven’t been tried and tested. 

Heat pumps have been used for decades and use the same core technology as air conditioning. A wide range of them are available today and the technology is constantly improving. 

Heat pumps have growing in popularity in Scandinavia since the 1980s [1] and roll out elsewhere in Europe has rapidly accelerated in the last few years. The UK is following suit with heat pumps right at the heart of a government policy to decarbonise heating that has an ambition to end the sale of gas boilers altogether by 2035 [2]. UK research has found they are suitable in many types of homes. An ongoing trial by Manx Utilities is now in its third phase. In phase one, a sample of new heat pump users surveyed presented an average of 91% satisfaction rate, with all users stating they would recommend the system to others. 

They have also been used in social housing in Ramsey since 2018 which has had a positive impact on tenant’s bills. 

We are delighted with the performance of the ASHP which exceeded our expectations – the running costs of an ASHP are significantly less than a gas boiler. The cost of installation is likely be prohibitive to most and this trial Scheme run by the MUA greatly assists in spreading the cost of the capital spend. Although the ASHP can be heard when sitting in the garden, the overall noise from the ASHP is no louder than the previous gas boiler when operating. We would only move home into another house if it had an ASHP.  - Manx Utilities ASHP Trial customer  

How long do they last? 

A properly and professionally maintained heat pump the average lifespan of an air source heat pump is 15-20 years for modern technology [3]. 

Will they work in a Manx stone cottage?  

It depends on your current heating system and the age and fabric of the building. If you currently have an old central heating system, you may have to change a number of radiators or insulate your home for a heat pump to work at its best efficiency. You should consult a reputable installer and ask for their advice. In some cases, particularly if you have an oil boiler, it may be preferable to use a biofuel in your existing boiler instead. However the Isle of Man Government are still working on biofuel availability for the Island. You could also consider biomass.  

Very satisfied, we live in an 1830s Manx Stone Cottage and the outcome has been beyond our expectations, we do highly recommend this to everyone! - Manx Utilities ASHP Trial Customer 

Does coastal air cause corrosion?  

Manufacturers have done a lot in recent years on corrosion-proofing of new materials on ASHPs and coatings to address exactly this problem. Reputable manufacturers supply product fit for coastal environments or anti-corrosive paint can be applied. You should check with the installer before they obtain a heat pump to make sure this is considered. 

Man fixing ASHP

How much maintenance do they require?  

They need less maintenance than gas, oil, or LPG systems because they don't use flammable fuels, so there is no risk of carbon monoxide accumulation. Seek your installer’s advice and adhere to manufacturer’s warranty criteria requirements on servicing. It is recommended to have a professional service every 2 to 3 years and they do require an occasional pressure check and an annual check for debris and service on the associated unvented water cylinder.  

WiLL IT provide MY HOME WITH enough heat?

It is important that your installer carries out a room-by-room heat loss survey to ensure that your ASHP is sized correctly to heat your home adequately. This also includes the sizing of the properties heat emitters such as radiators and UFH systems. A correctly sized system will provide adequate heat which is comfortably distributed throughout the day. 

In a sample survey of customers of the first Manx Utilities trial, customers rated the room temperatures provided by their ASHP 4.9/5, hot water temperatures provided 5/5 and hot water pressure 5/5. 

Related blogs and pages; 
Phasing out fossil fuel heating 
Low carbon heating options 
8 common myths about air source heat pumps explored 
Why hydrogen is unlikely for home heating 



  • Air Source Heat Pumps
  • Home Energy
  • Electricity
  • Green Energy