Heat pump vs storage heaters is one of the most important comparisons for UK homes that are off the gas grid — a significant proportion of UK flats, rural properties, and older housing stock. If you’re currently relying on storage heaters and wondering whether a heat pump would cut your bills, this guide gives you the honest answer with real numbers. The short version: at a COP of 3 or above, a heat pump delivers three times as much heat per unit of electricity as a storage heater — and the running cost difference for a typical home amounts to hundreds of pounds per year. But the installation cost, grant eligibility, and property suitability picture is more nuanced than that headline suggests.
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How storage heaters work
A storage heater contains a core of dense ceramic bricks with heating elements running through them. Overnight, the elements switch on and heat the bricks up to 600–700°C. During the day, the stored heat radiates out of the bricks — either by convection through vents (in fan-assisted models) or through natural radiation (in older manual models). The logic was designed around Economy 7 electricity tariffs: charge overnight on the cheap rate, discharge during the day on the standard rate.
Modern storage heaters — such as the Dimplex Quantum, Elnur Ecombi, and Creda TSR — have improved significantly over the old fixed-charge units. They have electronic charge control, temperature sensors, and some models can respond to time-of-use tariff signals. But their fundamental physics hasn’t changed: they are 100% efficient. Every unit of electricity in becomes exactly one unit of heat out. There is no multiplication effect — no COP greater than 1. The Energy Saving Trust’s guide on storage heaters confirms that even the most modern models cannot exceed 100% electrical efficiency.
This is their key limitation against a heat pump. A storage heater is electrically efficient but thermodynamically limited. A heat pump moves heat from outside air using a refrigerant cycle, which allows it to deliver 2–4 units of heat for every unit of electricity consumed.
How air source heat pumps work in this comparison
An air source heat pump (specifically an air-to-water type) connects to a wet central heating system — radiators or underfloor heating — and a hot water cylinder. It extracts low-grade heat from outside air and concentrates it via a refrigerant circuit, delivering that heat at a useful temperature into your water circuit. The ratio of heat output to electricity input is the COP — typically 2.5–4.0 depending on the outdoor temperature and the flow temperature required. The Heat Pump Association’s explainer gives a good overview of how the refrigerant cycle works in practice.
Over a full UK heating season, the average seasonal COP (SCOP) for a well-installed system is 2.8–3.5. This means that for a home that needs 14,000 kWh of heat per year for space heating, a heat pump with SCOP 3.0 consumes approximately 4,667 kWh of electricity — versus the 14,000 kWh a storage heater system would consume to deliver the same heat output.
Running cost comparison: storage heaters vs heat pump
We’ll use a 3-bed semi-detached home with 14,000 kWh space heating demand and 2,500 kWh hot water demand (16,500 kWh total). All costs in current 2026 electricity prices. Savings vary depending on property size, insulation, and energy tariff.
Storage heaters on Economy 7
Economy 7 gives a cheap overnight rate and a higher daytime rate. A common current split under Ofgem’s price cap is approximately 12p/kWh overnight and 32p/kWh daytime. Storage heaters charge overnight on the cheap rate — so you get the cheap electricity for heating, but only if you can predict the next day’s demand accurately. If you undercharge, you top up on daytime rates. If you overcharge, heat escapes wastefully overnight.
Assuming 75% of storage heater electricity consumed at the cheap rate and 25% at the daytime rate — a realistic split for a well-managed system:
- Space heating electricity: 14,000 kWh (100% efficient)
- Hot water (immersion): 2,500 kWh
- Total: 16,500 kWh
- Blended cost (75% × 12p + 25% × 32p): approximately 17p/kWh average
- Annual electricity cost: approximately £2,805
Air source heat pump on Octopus Cosy
Octopus Cosy is designed for heat pump households and offers cheap electricity during 4–7am and 1–4pm daily. Blended rate for a heat pump household: approximately 17p/kWh (shifting compressor hours to cheap periods).
- Space heating electricity: 14,000 ÷ 3.0 (SCOP) = 4,667 kWh
- Hot water electricity: 2,500 ÷ 2.5 (COP) = 1,000 kWh
- Total electricity: 5,667 kWh
- Blended Cosy rate: 17p/kWh
- Annual electricity cost: approximately £963
Annual saving with a heat pump vs storage heaters: approximately £1,842 per year in this example. Even at a more conservative SCOP of 2.5 and a standard electricity tariff of 25p/kWh, the heat pump still comes out at approximately £1,417/year — over £1,000 cheaper than the storage heater scenario.
Head-to-head comparison table
| Factor | Storage heaters (Economy 7) | Air source heat pump (Octopus Cosy) |
|---|---|---|
| Efficiency | 100% (1 kWh in = 1 kWh heat) | 250–350% (1 kWh in = 2.5–3.5 kWh heat) |
| Annual electricity (3-bed semi) | ~16,500 kWh | ~5,700 kWh |
| Annual running cost (example) | ~£2,800 | ~£960 |
| Provides domestic hot water | No — needs separate immersion | Yes — includes hot water cylinder |
| Installation cost | £150–£400 per heater (no grant) | £8,000–£14,000 (£7,500 BUS grant available) |
| Net installation cost after grant | £1,000–£2,500 for whole house | £500–£6,500 after grant |
| Comfort level | Front-loaded heat; can run cold by evening | All-day consistent warmth |
| Control flexibility | Limited — charge overnight, use next day | Full scheduling, smart tariff integration |
| Works without wet central heating | Yes | No — needs radiators or UFH |
| Maintenance | Low — no moving parts | Annual service recommended (£100–£200) |
Economy 7 vs Octopus Cosy: which tariff helps more?
Economy 7 was designed for storage heaters in the 1970s. It gives 7 hours of cheap overnight electricity, which is exactly the charging window the heaters were designed for. Modern smart Economy 7 meters can shift which 7 hours are “cheap” — but the fundamental problem remains: you’re committed to consuming all your heat energy during those overnight hours, regardless of what the next day’s weather holds.
Octopus Cosy gives cheap windows twice a day (4–7am and 1–4pm on weekdays), which aligns much better with how a heat pump operates — running in shorter cycles throughout the day rather than one long overnight charge. The daytime cheap window is particularly valuable in summer and spring, when a heat pump has very low demand and runs briefly in the early afternoon for a small top-up.
The key insight is that Octopus Cosy was built for heat pumps, not for storage heaters. Economy 7 was built for storage heaters, not for heat pumps. Using each technology with the right tariff gives very different results from using either with the wrong tariff.
Comfort comparison: the real-world experience
Storage heaters have a well-known problem: they run warmest in the morning when rooms are fully charged, and coolest in the evening when you actually want warmth — unless you have a fan-assisted model with a good output controller. By 7–8pm on a cold day, older storage heaters are often barely warm. Modern models with electronic charge control and output fans do better, but the fundamental energy storage curve remains front-heavy.
An air source heat pump provides consistent warmth throughout the day because it’s generating heat on demand — it runs the compressor as needed to maintain your set room temperature. There is no charge/discharge cycle. On a cold winter afternoon, your house stays at 21°C whether it’s 2pm or 9pm. This is a qualitative improvement that’s hard to quantify but very real for households who currently experience cold evenings.
Installation costs and BUS grant eligibility
This is where the comparison gets more complex. Installing storage heaters is cheap: a set of three or four modern fan-assisted storage heaters for a 3-bed home costs £1,000–£2,500 installed, with no grant available.
An air source heat pump installation for a home without existing wet central heating is more involved — you’ll need the heat pump unit, a hot water cylinder, and a complete wet central heating system installed (radiators, pipework, and a pump). This is a significant project: expect £12,000–£20,000 for a full installation from scratch. The Boiler Upgrade Scheme grant of £7,500 reduces this significantly, and you may also be eligible for ECO4 funding if your property meets the energy efficiency criteria.
If you already have a wet central heating system but no gas (for example, you previously had oil heating and recently removed it, or you have electric radiators on a wet system), a heat pump installation is considerably cheaper — more like £8,000–£12,000 before the grant. See our full guide to heat pump grants for current eligibility rules.
The payback calculation works in the heat pump’s favour: if you save £1,500–£1,800 per year on running costs (as per our worked example above), a £5,000 net installation cost pays back in 3–4 years. Even a £10,000 net cost pays back in 6–7 years — while you’re also reducing carbon emissions and increasing your home’s EPC rating.
Is a heat pump worth it if you have storage heaters?
For most off-gas homeowners with storage heaters, the answer is yes — subject to two conditions: your property is suitable for a heat pump (not a very small flat or a poorly insulated property with no budget for insulation improvements), and you have or can install a wet central heating system.
The running cost saving is substantial and ongoing. The installation cost, while higher than replacing storage heaters, is significantly offset by the BUS grant. And you gain consistent all-day comfort, domestic hot water integration, and a lower carbon footprint.
For a broader assessment of whether a heat pump is the right move for your specific situation — including property type, insulation level, and budget — see our is a heat pump worth it guide. And for a full breakdown of heat pump costs including grants and installation, our grants guide covers everything you need to know. If you’re also considering solar panels alongside a heat pump — which can further cut your electricity costs — SolarBlog covers the solar and heat pump combination in detail.