For years, the case against electric combi boilers came down to one number — the flow rate. Standard electric combis simply could not match the volume and temperature delivered by a gas combi, which meant baths took an age to run, and any property without mains gas was stuck choosing between a noisy, space-hungry unvented cylinder setup or a compromise on hot-water comfort. The Strom AuraHeat Stored Combi Boiler rewrites that compromise. By placing a 35-litre stainless steel buffer tank inside the boiler casing and feeding it through a patented Recirc circuit, AuraHeat delivers flow rates of up to 12 litres per minute at a 30°C temperature rise — comfortably within bath-filling territory — while keeping the compact, wall-hung form factor that makes electric combis so attractive in the first place.
This guide unpacks how the AuraHeat works, why its Recirc Technology represents a genuine first in the UK electric boiler market, how the two models compare, the applications it suits best (including underfloor heating), and a powerful pairing strategy that lets you trim running costs by combining it with a Strom instantaneous water heater for low-demand outlets.
How AuraHeat's Recirc Technology Works
To understand why the AuraHeat performs so differently from a conventional electric combi, it helps to know what a standard electric combi has to do. When you open a hot tap, ambient cold mains water (often as low as 5°C in winter) flows through the boiler's instantaneous heating element. The element has a fixed kW rating, so the boiler is forced to choose between high temperature at low flow, or moderate temperature at higher flow — you cannot have both. This is the physics that has always capped electric combis at around 5–7 LPM at usable bathing temperatures.
The Strom AuraHeat sidesteps the problem with a four-step circuit:
Pre-heated Store
A 35-litre stainless steel tank, fitted with an integrated coil, is heated by the boiler to up to 80°C and held there until needed.
Digital Blending Valve
Stored hot water is mixed with incoming mains water through a programmable blending valve, producing a precisely controlled feed temperature.
Top-up Element
That pre-warmed blend passes through the instantaneous heating element — which only has to add a few degrees, not heat from cold.
Delivered at Flow
The result is up to 12 LPM at a 30°C rise — bath-filling performance from a single-phase 230V electric boiler.
The store extends the “effective kW” of the instantaneous element without needing a separate cylinder or three-phase supply. Once the buffer depletes, performance falls back to the instantaneous element alone — still a respectable 7 LPM — and the boiler then reheats the tank in around 20–22 minutes ready for the next demand. For UK households whose hot water use is concentrated in showers, baths, and dish-washing rather than running continuously all day, this is an extraordinarily efficient way to deliver gas-combi-like performance from an all-electric appliance.
Four Programmable Modes — You Decide When the Tank Runs
One of the more underrated features of the AuraHeat is that the buffer tank does not have to be heated continuously. Strom has built in four operating modes, letting you trade peak performance against standing losses depending on lifestyle, tariff, and the time of year.
Always On
The tank stays at its set temperature 24/7 — full performance is available at any time. Best for households with unpredictable hot-water demand or guest-facing properties.
Always Off
The tank is left cold and the boiler operates exactly like a standard instantaneous electric combi. Useful during low-demand periods (e.g. holidays) to eliminate standing losses entirely.
Boost Once
A single on-demand reheat — tap the control, wait roughly 20 minutes, and the full 12 LPM performance is available. Ideal before bath night or a busy morning.
Timed On
Schedule the tank to heat at the same time daily — perfect for pairing with Economy 7, Cosy Octopus, or Agile tariffs where you want hot water ready just before cheap-rate windows end.
What Actually Makes the AuraHeat Unique
The UK electric boiler market is reasonably crowded, but most products fall into one of two camps: dry-element instantaneous combis (compact but flow-limited) or boiler-plus-cylinder packages (powerful but bulky and expensive to install). The AuraHeat is one of the first products in the UK to combine the buffering benefit of a cylinder with the wall-hung footprint and integrated controls of a combi. The key differentiators:
Patented Recirc Circuit
Stored water is recirculated through the heating element rather than dispensed directly — the only UK electric combi that does this in a single unit.
Stainless Steel Construction
The integral tank is duplex stainless steel with an internal coil — inherently scale-resistant, ideal for the UK's hard-water belt.
Built-in Diverter Valve
A single boiler now drives both central heating and DHW priority through one factory-fitted diverter — no separate motorised valves to specify.
Programmable Priority
The user can configure whether the AuraHeat prioritises stored volume, peak flow rate, or balances both — rare flexibility in the electric category.
Single-Phase 230V Operation
Both models run on standard UK single-phase supplies, avoiding the three-phase upgrades that limit so many higher-output electric solutions in domestic flats.
Compact Footprint
At 920 × 570 × 300 mm, the AuraHeat fits in a standard airing cupboard or utility space — far smaller than a boiler-plus-cylinder install.
AuraHeat vs Standard Electric Combi vs Gas Combi
Here is how the AuraHeat compares with the alternatives on the metrics that actually drive specification decisions:
| Specification | Strom AuraHeat | Standard Electric Combi | Gas Combi (Mid-Range) |
|---|---|---|---|
| Peak DHW Flow (ΔT 30°C) | Up to 12 LPM | 5–7 LPM | 10–13 LPM |
| Bath Suitable | ✓ Yes | ✗ Marginal | ✓ Yes |
| Mains Gas Required | ✗ No | ✗ No | ✓ Yes |
| Flue Required | ✗ No | ✗ No | ✓ Yes |
| Annual Service | Recommended | Recommended | Legally required (Gas Safe) |
| Combustion Emissions on Site | None | None | CO₂, NOx, water vapour |
| Power Supply | 230V Single-Phase | 230V Single-Phase | 230V + Gas |
| Compatible with Underfloor Heating | ✓ Yes (low-temp friendly) | ✓ Yes | ✓ Yes |
| Suits Solar PV / Time-of-Use Tariffs | ✓ Excellent | Limited | ✗ No benefit |
Applications: Where the AuraHeat Excels
The AuraHeat is not a one-size-fits-all replacement for every gas boiler in the UK — but for a specific (and growing) set of properties, it is genuinely the best answer on the market. The combination of a stored buffer, low-temperature compatibility, and a single 230V supply gives it an unusually wide application envelope.
Off-Gas Homes & Rural Properties
Properties without a mains gas connection have historically had two choices: oil/LPG (with all the storage, regulation, and emissions baggage) or an electric system that compromises on hot water. The AuraHeat removes that compromise — bath-filling flow rates from a single-phase electric supply.
New-Build Flats & Apartments
Part L 2025 and the Future Homes Standard are pushing UK developers away from gas. The AuraHeat fits within a typical utility cupboard footprint and avoids the cost of running a gas line into every dwelling — ideal for both private and social-housing apartment blocks.
Underfloor Heating Systems
UFH systems operate at 35–55°C flow temperatures — well within the AuraHeat's 30–80°C heating range. Pairing the AuraHeat with a wet UFH manifold gives you whole-floor heating and stored DHW from a single appliance — particularly attractive for ground-floor extensions, garden rooms, and energy-efficient retrofits.
Solar PV Households
If you have solar PV on the roof, the “Timed On” mode lets you schedule the tank reheat to coincide with peak generation hours, effectively storing solar energy as hot water for evening use — meaningful running-cost savings without needing a battery.
Holiday Lets & Second Homes
The four operating modes shine here. Run the boiler in “Always Off” mode when the property is empty (no standing losses), then switch to “Always On” or “Boost Once” on arrival. No flue, no Gas Safe certificate, no combustion check required.
Retrofit Replacements for Gas Combis
For homeowners decommissioning a failing gas combi who want to stay all-electric (e.g. preparing for an ASHP-ready future), the AuraHeat is one of the few electric combis that genuinely matches gas-combi hot-water performance — making the transition feel like an upgrade, not a sacrifice.
Shop the Strom AuraHeat Range
The AuraHeat is supplied in two single-phase output ratings — both built around the same 35-litre stainless steel store and Recirc circuit. Pick the output based on property heat loss and peak DHW demand.
Code SBSP9SC. 35L stainless steel store, 10 LPM peak flow at ΔT 30°C, 22-min reheat. Suits 1–2 bedroom flats and well-insulated 3-bed homes. Requires 50A breaker and 10mm² cable.
Code SBSP13SC. Same 35L store, but 12 LPM peak flow and 20-min reheat. The pick for larger 3–4 bedroom homes, properties with higher heat loss, or systems with substantial UFH zones. Requires 63A breaker.
Cut Running Costs: Pair AuraHeat with a Strom Instantaneous Heater
One of the smartest installer-led moves we see on AuraHeat installs is to not make the AuraHeat do every hot-water job in the property. For an en-suite cloakroom on the far side of the house, a utility-room sink, or a garden office — outlets where you draw small volumes occasionally — running the AuraHeat's buffer down and back up again is wasteful. The water has to travel a long pipe run, you get a cold slug at the start, and the buffer reheat cycle fires up for what was effectively 30 seconds of demand.
The fix is a Strom Touch Screen Instantaneous Water Heater sited locally at the low-demand outlet. Available in 9kW, 11kW, and 13.5kW single-phase outputs, the unit heats only the water that's drawn — no tank, no standing losses, no pipe-run wastage. Total spend is modest, and you get two benefits at once:
- Lower running cost on the main AuraHeat circuit, because the buffer is reserved for the high-volume outlets (bath, main shower, kitchen sink) where its flow-rate advantage actually pays off.
- Better user experience at distant outlets — instant hot water with no “run-off” before it gets warm, particularly noticeable in larger homes or two-storey properties.
Compact 358 × 246 × 85mm wall-mounted multipoint heater in 9kW, 11kW, and 13.5kW single-phase outputs. Touch-screen control, mains-pressure delivery, and zero standing losses — ideal for local en-suite, utility, and garden-office use alongside an AuraHeat.
Full Technical Specification
For installers and trade specifiers, here is the complete data sheet for both AuraHeat models in one view:
| Specification | AuraHeat 9.5kW | AuraHeat 13.5kW |
|---|---|---|
| Product Details | ||
| Product Code | SBSP9SC | SBSP13SC |
| Dimensions (H×W×D) | 920 × 570 × 300 mm | 920 × 570 × 300 mm |
| Weight (Empty) | 40 kg | 43 kg |
| Weight (Full) | 75 kg | 78 kg |
| Electrical Specification | ||
| Rated Voltage | 230V Single-Phase | 230V Single-Phase |
| Min. Recommended Breaker | 50A | 63A |
| Rated Current | 46A | 62A |
| Minimum Cable Size | 10 mm² | 10 mm² |
| Hydraulic Specification | ||
| Heating Flow & Return | 3/4″ Male | 3/4″ Male |
| DHW Inlet & Outlet | 1/2″ Male | 1/2″ Male |
| Fill Connection | 1/2″ Male | 1/2″ Male |
| Pressure Relief Connection | 1/2″ Female | 1/2″ Female |
| Heating Temperature Range | 30–80°C | 30–80°C |
| Hot Water Temperature Range | 30–55°C | 30–55°C |
| Heating Circuit Pressure | 0.5–3.0 Bar | 0.5–3.0 Bar |
| DHW Circuit Pressure | 0.1–6.0 Bar | 0.1–6.0 Bar |
| Performance | ||
| Recommended DHW Flow (ΔT 30°C) | 10 LPM | 12 LPM |
| Tank Reheat Time | 22 minutes | 20 minutes |
| ErP Heating | D | D |
| ErP DHW | A | A |
Optional Accessory: Strom Fittings Pack
Whichever AuraHeat output you specify, the install will need a set of compliant isolation valves at the boiler connections. Rather than sourcing them piecemeal, the Strom Fittings Pack is matched specifically to the AuraHeat's connection sizes — saving merchant trips and removing any compatibility guesswork.
Strom Fittings Pack for Combi Boilers
Complete isolation-valve kit for the final connections to a Strom AuraHeat. Includes two 22mm flat-faced isolation valves for the central-heating flow and return, two 15mm flat-faced isolation valves for the DHW inlet and outlet, plus the additional fittings needed to land the boiler cleanly on site.
Built & Certified to UK Standards
Frequently Asked Questions
Can the AuraHeat actually fill a bath?
Yes — this is the headline upgrade over conventional electric combis. With the 35-litre store at full capacity, the 13.5kW model delivers up to 12 LPM at a 30°C temperature rise (the 9.5kW model delivers 10 LPM). A standard UK bath holding roughly 80–100 litres can therefore be filled to comfort temperature in around 8–10 minutes from the 13.5kW — comparable to a mid-range gas combi. Once the buffer is depleted, the boiler continues to supply DHW from the instantaneous element alone at around 7 LPM.
Will the AuraHeat work with underfloor heating?
Yes — very well. The AuraHeat's heating circuit temperature is adjustable from 30°C to 80°C, which spans the typical 35–55°C flow temperatures used by wet UFH systems. The integral diverter manages priority between heating and DHW automatically, so a single AuraHeat can run a whole-floor UFH manifold and provide stored hot water without any external valves or controls. For mixed systems (UFH on one floor and radiators on another), use a low-loss header or two-port mixing valve to manage the different flow temperatures.
Do I need three-phase electricity to install it?
No. Both AuraHeat models are designed for single-phase 230V domestic supplies. The 9.5kW model requires a 50A breaker and 10mm² cable; the 13.5kW model needs a 63A breaker on the same 10mm² cable. Most modern UK consumer units can accommodate this, but a qualified electrician should confirm the available supply capacity and submit Part P certification.
What hot water temperature can the AuraHeat reach?
The DHW outlet temperature range is 30–55°C. The 35-litre internal store itself can hold water at up to 80°C, but that stored water is blended down through the digital blending valve before reaching the tap, ensuring safe delivery temperatures and protecting the heating element from thermal shock. The 55°C upper limit at the tap is consistent with safe-touch guidance for domestic outlets.
How much does the AuraHeat cost to run compared to gas?
On standard UK unit-rate comparisons, electricity per kWh is currently around 3–4× the cost of mains gas, so headline running costs on a single-rate tariff will be higher than a gas combi. The picture changes considerably with time-of-use tariffs (Economy 7, Cosy Octopus, Agile Octopus), solar PV exporting at home, or off-peak hot-water scheduling using the “Timed On” mode — all of which the AuraHeat is designed around. For properties without mains gas, the comparison is against oil, LPG, or storage heaters, where the AuraHeat is usually cheaper to run and considerably more comfortable.
Does it need a flue, gas-safe certificate, or annual service?
No flue is required — the AuraHeat produces zero combustion emissions on site. A Gas Safe certificate does not apply because it is an electrical appliance; instead, installation requires Part P notification and certification by a qualified electrician (NICEIC, NAPIT, ELECSA or equivalent). An annual check of the pressure-relief valve, expansion vessel pre-charge, and system pressure is recommended, but not legally mandated as it is for gas appliances.
Is it scale-resistant in hard-water areas?
The 35-litre integral store is stainless steel with an integrated coil — the same material used in unvented mains-pressure cylinders for hard-water resistance. In high-hardness areas (parts of south-east England, East Anglia, parts of the Midlands), Strom recommends installing a scale-reduction device or salt-free water conditioner upstream of the boiler. Browse our water treatment range for compatible options.
Which model is right for me — 9.5kW or 13.5kW?
The 9.5kW (SBSP9SC) suits 1–2 bedroom flats, well-insulated 3-bed homes, and properties with modest UFH zones. The 13.5kW (SBSP13SC) is the right pick for 3–4 bedroom homes, properties with higher heat loss, large UFH installs, or households with high simultaneous hot-water demand (e.g. multiple bathrooms). When in doubt, size on heat loss first — an under-sized boiler will struggle to maintain comfort on the coldest design days — and check that the 13.5kW's 63A breaker requirement is supported by the property's consumer unit.
Explore Related Products & Guides
If you are still in the research phase, these collections and guides on AIZO Quality Heating will help you build out a complete all-electric heating specification:
- Electric Boiler Collection — full range of Strom and other UK-market electric boilers in heat-only, combi, and stored-combi formats.
- Water Heaters Collection — instantaneous, multipoint, and storage water heaters for pairing with electric heating systems.
- Water Underfloor Heating — manifolds, pipe, and accessories for wet UFH systems compatible with the AuraHeat.
- Water Heaters Buying Guide — helps you decide between stored, instantaneous, and combi-based hot-water solutions.
- Electric Boilers with Solar PV — how to make AuraHeat-style systems pay for themselves on solar households.
- Electric Boilers FAQ — general questions on running costs, sizing, and installation.
Ready to Specify a Strom AuraHeat?
Whether you are a homeowner planning an all-electric replacement, an installer specifying a new-build apartment system, or a developer briefing a low-carbon housing scheme — our team can help size the right AuraHeat, the right accessories, and the right pairing strategy for your project.
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