Joanna O’Loan: upgrading storage heaters with an air source heat pump

In 2020, I purchased an 1870s home with an old electric storage heating system. I had two options: upgrade the storage heaters or look at an air source heat pump. I went with an air source heat pump for a few reasons:

• Cheaper running costs than a storage heating system.
• Removing heaters from my walls freed up wall space, replacing them with underfloor heating.
• I had little opportunity for insulation as the walls are very thick stone. External wall insulation was not suitable as I live in a conservation area and internal wall insulation would take up too much space. There’s an apartment above me, so no loft to insulate. Floor insulation in suspended timber floors was the most reasonable option to improve insulation (and shared costs with underfloor heating system).

I applied for the Home Energy Scotland Loan to help with the cost of installing the air source heat pump. After speaking with several installers, I received a range of quotes for the heating system and heat pump between £7,000 and £19,000. Booking installers to quote took a few weeks and I received my loan offer after two months.

Unfortunately, in the meantime, my selected installer had filled their schedule with other installs, which added another month’s delay. The heat pump manufacturer was also experiencing delays in production, which added another few months to the process. It wasn’t quite as smooth a ride as I’d expected, but this was during lockdown!

I’m really enjoying the underfloor heating. It saves space on my walls in a small flat and it’s a very comfortable way to heat my home. I didn’t live with the storage heaters, but I would think it’s a cheaper system to run, too. I’m so far getting between 3-4 times the heat as my electricity input, even through the recent cold, snowy spell in February.

Not yet, but I am about to apply for Renewable Heat Incentive (RHI) payments. It was definitely a factor, as it will help to recover at least some of my installation costs.

Invite lots of installers round to your property and ask them lots of questions. Don’t be afraid of sounding stupid. You’re the person who has to live with it, so it needs to be installed as you’ll use it – which is not necessarily the easiest or more routine for them to install.

Ask lots of questions about why that size of heat pump or hot water cylinder has been selected, why that insulation has been selected, why that heating distribution system is being used, what controls they’d recommend, and so on. Installers will have different ideas, so ask them to justify their decisions and convince you. Let them know what other installers have suggested as alternatives and ask them to critique.

Look at your metering. With the storage heating system, I had a complex metering (restricted meter). I had three rates for my electricity supply, a separate one for my storage heaters and hot water, plus a day and night rate for all my other electricity use. This set up isn’t really compatible with a heat pump that needs power throughout the day and limits me to a single tariff. So, I arranged to get that meter changed to a single rate meter after my heat pump was installed.

If you do go for it, wear your project manager hat! There’s likely to be a few different contractors, although this should all be organised by your heat pump installer. Just keep an eye on timescales and what’s been promised, when.