Giving up gas for good


Lewes resident Diana Wilkins recounts her household’s journey switching from a gas boiler to an air-source heat pump to heat their home – and what it’s meant so far for running costs as well as their carbon footprint.

In the autumn of 2021, our condensing gas boiler failed its routine service. However, we didn’t want to spend thousands of pounds on a new gas boiler which we knew would soon be obsolete as it wouldn’t be clean enough to meet the UK’s climate targets. We decided to look instead at the potential for an air-source heat pump.


Doing the research

However, I was uncertain how to retrofit our home and wanted to hear real-life experiences of using heat pumps. I felt more confident after watching Transition Town Lewes’s online talks about ‘Eco Open Houses’. I also contacted the Lewes Climate Hub for advice about where to find information about heat pumps and accredited installers such as Ohm Energy and Viessmann. Finally, Ohm Energy arranged for us to visit one of their heat pump customers. I was pleasantly surprised the that their house was warmer than our conventionally-heated home, and reassured that the heat pump was both quiet and a reasonable size.


Financing the switch

Image: Mitsubishi Ecodan 6kW air source heat pump

To help pay for the heat pump we turned to the Boiler Upgrade Scheme (BUS), run by the energy regulator, Ofgem. This provides £5000-6000 towards the cost of a clean heating system, including heat pumps which may cost around £10,000. More recently, Octopus energy has launched a scheme to install a standard heat pump for £3000-£4000 (including the BUS grant), reduced to £2000 for Halifax customers.

The application for the BUS grant is done by the installer rather than the householder. However, to be eligible we needed an Energy Performance Certificate issued in the last ten years that showed we had no outstanding recommendations to fit loft/cavity wall insulation. A local EPC assessor visited us for an hour and produced a report the same day for £60. We were pleased that our previous actions (such as installing solar panels, changing from a gas to an induction hob for cooking and replacing halogens with LED lights) had improved our rating from C to B. We also fitted thermal blinds to reduce draughts and moved furniture so that the heat from radiators could circulate more efficiently.


Installation requirements

Image: Mitsubishi Ecodan hot water cylinder and pumps for air source heat pump

Although we were ready to go, we were hit by a delay in the transport of heat pumps from their manufacturing base in China. As a result, our installation was postponed from the spring to summer 2022, but this also meant it was more comfortable being at home during the four days while the new system was being fitted.

In terms of practicalities, the heat pump needs a hot water cylinder (pictured) which we had installed in a downstairs utility room. For us, this arrangement minimised the amount of pipework involved, but it is also possible to put the tank in a loft. The 6-kilowatt heat pump (pictured) went in the garden, where it needs to be a minimum of one metre from any boundary. Since we have modern convecting, double panel (K2) radiators, we didn’t need to change them, but we did replace our bathroom towel rail with a conventional radiator to provide more heat.


Running costs

Turning to the nitty-gritty of running costs, before the heat pump was installed, we estimated that it might cost a similar amount to run as our gas condensing boiler system. However, that was before the recent hike in energy prices, and now it’s likely that the heat pump will save us money and protect us against future rises in gas prices.

During the summer, when we used the heat pump just for hot water, it cost around 60 pence a day for two people.[1] Since we started using the heating in the autumn, we have paid an average of around £3 per day for heating and hot water.[2] The heat pump performed well during the cold spell in December with a target temperature of 20°C during the day and 16°C at night.

We will of course only have an idea of complete running costs once we have a full year’s worth of usage data. Actual running costs for individual households vary widely, depending on the outdoor temperature and household circumstances, for example, the number of people, time spent in the house, room temperature and level of insulation.

Given that we also have an electric car with a home charger, we no longer use any fossil fuels directly. Electrifying our life has substantially reduced our carbon footprint. Our carbon dioxide emissions in 2021, from running the house and the car, were 1.2 tonnes. This compares with average emissions in the UK of around 3 tonnes for home energy and an additional 2 tonnes for transport per household. As a bonus, going entirely electric helps reduce local air pollution from cars and gas boilers.

Nearly all households will need to electrify their heating and transport in the next few years if the UK is to meet its climate commitments. For us, getting a heat pump has taken quite a lot of planning, but it’s been worth it for a warm home, heated by renewable energy.


Heat Pump Checker
The Department for Business, Energy and Industrial Strategy (BEIS) has created a guide for homeowners considering purchase of heat pumps, including a checker for homeowners to assess the suitability of their home for a Heat Pump.  Find out more at:


[1] During August 2022, the heat pump used 53kWh of electricity. At a current unit cost of 33.6 p per kWh, that would cost £17 (excluding standing charge).

[2] From 1 September to the end of December 2022, the heat pump used 777kWh of electricity. At the current unit price of 33.6 p per kWh, the cost was £261 for heating and hot water, for a household of two people living in a 3-bed detached house.


1 Comment

  1. Wisepersons

    Very well done Diana Wilkins. We have had our heat pump (plus solar panels of course) for 5 years now. We still get our £1200/year back – will stop in 2 years time. Our house was already well insulated and you must be ‘B’ I believe to get the subsidies. The actual air source heat pumps are now smaller – our is quite a beast in the garden. Obviously after the combi gas boiler, the tanks are huge and need space. However, we have reduced our carbon footprint massively. Not sure it has saved us that much money on heating over the past 5 years.


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