Aren't modern high-heat-retention storage heaters (HHRSHs) close to a heat pump on running cost?

Closer than older NSHs, but not equivalent. HHRSHs hit ~95% efficiency vs ~99% for a heat pump's compressor cycle but they still output 1 kWh of heat per 1 kWh of electricity used — the same fundamental limit as any direct-electric system. A heat pump at SCOP 3.5 outputs 3.5 kWh of heat per 1 kWh of electricity. Even on identical tariffs the heat pump wins on running cost; on a heat-pump-specific tariff the gap widens to £400–£900/year for a typical UK flat or small house.

I live in a flat with no outdoor space — can I still get a heat pump?

Often yes — air-source units have shrunk substantially and some installs work on private balconies, light wells, or shared roofs with the freeholder's consent. Pre-survey your specific property at propertoasty.com/check; an installer will need to assess the siting, noise compliance (MCS 020), and management-company consent. If outdoor siting genuinely fails, modern HHRSHs are the next-best option — but the running-cost gap to heat pumps stays meaningful.

What happens to my Economy 7 tariff when I switch to a heat pump?

You'd typically switch to a heat-pump-specific tariff (Octopus Cosy, British Gas Heat Pump Plus, EDF GoElectric) at the same time as commissioning. These tariffs work similarly to Economy 7 in spirit — cheap overnight rates plus targeted cheap windows during heat-pump operating hours — but the cheap-rate windows are configured around heat-pump load patterns rather than the fixed 11pm–7am Economy 7 window. Net effect: you keep the cheap-electricity benefit but apply it 3.5× more efficiently.

Does the BUS grant apply to storage-heater swaps?

Yes — the £7,500 Boiler Upgrade Scheme applies to any home in England or Wales switching to a low-carbon heating system, regardless of the existing setup. Storage-heater swaps are an under-recognised segment of BUS uptake. The grant typically covers most or all of the install cost for a small flat or 1-bed property.

Heat pump vs night storage heaters in 2026: comfort + cost guide

Heat pump vs storage heaters — typical UK numbers in 2026
	Air-source heat pump	Modern HHRSHs	Older NSHs
Install cost (pre-grant)	£8,000–£14,000	£2,500–£4,500	£1,500–£3,000
BUS grant	−£7,500 (E&W)	—	—
Net upfront cost	£1,500–£6,500	£2,500–£4,500	£1,500–£3,000
Efficiency (heat / kWh in)	~3.5 (SCOP)	~0.95	~0.90
Annual fuel cost (typical 70m² flat)	£600–£900	£1,000–£1,400	£1,200–£1,800
Comfort — evening heat?	On demand	Often depleted	Mostly depleted
Tariff	Heat-pump TOU	Economy 7	Economy 7
Outdoor footprint	1 × 1 m unit	None (indoor)	None (indoor)
Hot water	Separate cylinder	Often immersion (3 kW)	Often immersion (3 kW)
Expected lifespan	15–20 years	20–25 years	20–30 years
Install time	2–3 days	1 day	1 day
Carbon emissions	~0.3–0.6 t CO₂/yr	~1.4–1.7 t CO₂/yr	~1.6–2.0 t CO₂/yr

Heat pump vs storage heaters — typical UK numbers in 2026— Ranges are typical for a 1–2 bed UK flat (~50–80 m²) where storage heaters are most common. Specific quote depends on heat-loss survey + MCS-certified installer assessment.

The Economy 7 story — and its weakness

Night storage heaters were designed in the 1970s to pair with Economy 7 tariffs: cheap electricity rates from ~11pm–7am, charging the heater’s thermal core overnight, then releasing that heat slowly through the day. Cheap to install, no plumbing required, uses spare-capacity nuclear baseload electricity. For households out of the house through the day, it worked well.

The weakness is what every UK NSH user knows from experience: by evening (when most households are home and want heat), the thermal core is largely depleted. You can boost on the peak-rate tariff but that’s exactly when electricity is most expensive — typically 3× the overnight rate. The result is either cold evenings or expensive boost usage, often both.

How heat pumps change the maths

A heat pump on a heat-pump-specific tariff (Octopus Cosy, British Gas Heat Pump Plus, EDF GoElectric) uses the same cheap-overnight-electricity trick that Economy 7 invented, but applies it 3.5× more efficiently. Cheap-rate windows align with overnight heating + hot-water cylinder charging; the system delivers heat on demand during the day rather than relying on a thermal core to coast through.

For a typical 1–2 bed UK flat needing ~6,000–8,000 kWh of heat per year, that translates to:

Older NSHs: ~7,000 kWh of electricity at ~13p/kWh Economy 7 average = £900/year, plus £200–£400 in peak-rate boost on cold evenings = £1,100–£1,300/year all-in.
Modern HHRSHs: Same kWh-in, slightly better retention so less peak-rate boost = £1,000–£1,200/yr.
Heat pump on a heat-pump tariff: ~2,000 kWh of electricity at ~15p/kWh average = £300, plus standing charges and cylinder heating = £600–£900/year.

Annual saving on switching: £400–£900 for a typical UK flat. Plus the comfort gain — heat on demand, not heat-when-the-core- has-it.

Comfort, not just running cost

Storage heaters share an unusual failure mode: they fail to deliver heat when you most want it. By evening, when a 1-bed flat is occupied + cooling down + wants comfortable temperatures, the thermal core has been releasing heat all day and is depleted. The mitigation (boost on peak rate) works financially up to a point but stops working meaningfully on cold weeks when boost usage compounds.

Heat pumps don’t have this failure mode. They operate continuously at low-intensity output, modulated to current heat demand. Evening comfort is identical to morning comfort because the heat is delivered in real time, not pre-stored. Owner-occupiers in flats often describe the switch as the first time their home has been comfortable through the evening in years.

The carbon angle

Both systems run on grid electricity, so per-kWh carbon is identical (~150 g CO₂/kWh on the 2026 UK grid). Heat pumps buy ~1/3 the kWh, so carbon drops ~70%. For a typical UK flat: ~1.6–2.0 t CO₂/yr (older NSHs) drops to ~0.3–0.6 t CO₂/yr (heat pump) — a saving comparable to switching off mains gas.

When storage heaters still make sense

Listed-building flats where outdoor siting genuinely fails. Same MCS 020 + Listed Building Consent constraints as other heat-pump switches. Modern HHRSHs are the upgrade path.
Leasehold properties with no consented siting. Some leasehold management companies don’t engage with heat-pump consents. Owner-led pressure has shifted this since 2023 but pockets remain.
Mid-tenancy rental propertieswhere the landlord won’t fund the install. A modern HHRSH replacement is a tenant-instigateable upgrade with sensible landlord agreement.

Switching pathway

Run a free pre-survey at propertoasty.com/check to confirm BUS eligibility for your specific property (flats often need siting + consent steps owner-occupiers can flag up-front).
If you’re leasehold or in a flat with shared freeholders, raise the heat-pump siting question with your management agent early. Pre-2020 leases rarely contemplated heat pumps explicitly so most can’t refuse on contract grounds, but consent paperwork takes time.
Switch to a heat-pump electricity tariff at commissioning. Storage-heater households on Economy 7 should expect the tariff change too — the new tariff is similarly cheap overnight but configured around heat-pump load patterns.

The takeaway

Storage heaters made sense in a 1970s grid with cheap overnight baseload and no MCS-certified installer supply chain. In 2026, the heat-pump-on-time-of-use-tariff option delivers the same cheap-electricity story 3.5× more efficiently and removes the “cold evening” failure mode that storage heaters bake in by design. After the £7,500 BUS grant, the day-one numbers also favour the switch. The edge cases (listed flats, intransigent management agents, mid-tenancy rentals) are real but narrow.