4
Heat pump ranges available
4.9–17.4 kW
Output range at A-7/W35
75°C
Max flow temperature
A+++
Top efficiency class
Stiebel Eltron is one of the most respected names in low-carbon heating — a German engineering firm with decades in renewable heating and a UK air source heat pump line-up that spans everything from a compact 4.91 kW single-phase unit for a well-insulated new-build to a 17.36 kW three-phase machine for larger period homes or small commercial buildings.
This guide walks through every current Stiebel Eltron air source heat pump on our range at AIZO Quality Heating, explains the difference between the HPA-O Trend, HPA-O Plus, HPA-O W Plus and WPL-A Premium platforms, breaks down the pre-configured cylinder packages, and sets out exactly what we need to know about your property to specify the right system.
The technology that sets Stiebel Eltron apart
All four ranges are inverter-driven monobloc air source heat pumps, but they differ meaningfully in refrigerant chemistry, sound signature, and finish — and those differences drive the choice of range.
Inverter-matched output
A variable-speed compressor matches heating output to demand instead of cycling on and off. Efficiency stays high across the full range of outdoor temperatures, and short-cycling wear is avoided.
High flow temperature
All ranges support flow temperatures up to 75 °C. That makes them viable for retrofit properties running existing radiator circuits — not just new-builds with underfloor heating.
Active cooling in summer
Circuit reversal provides active cooling when paired with a compatible area heating system (typically underfloor). One unit covers heating, hot water and summer comfort.
Smart app control
Add the ISG accessory for MyStiebel app control and installer remote diagnostics. Modbus and KNX integration is supported for home automation, BMS integration and PV self-consumption.
R290 vs R454C: two natural refrigerant paths
The single biggest technical difference across the Stiebel Eltron range is refrigerant chemistry. The HPA-O family uses natural propane (R290); the WPL-A Premium platform uses the low-GWP HFO blend R454C. Both are dramatically lower-impact than the legacy HFC refrigerants (R32, R410A) that still dominate much of the market.
R290 (propane) — HPA-O Trend / Plus / W Plus
- Global Warming Potential of just 3
- Future-proofed against F-Gas HFC phase-down
- Excellent low-temperature performance
- Mildly flammable (A3) — installation clearances apply
- Newer platform, widest capacity range (4.9–17.4 kW)
R454C (HFO blend) — WPL-A Premium
- GWP under 150 — over 10x lower than legacy HFCs
- Non-flammable classification (A2L, mild)
- Established Premium platform used across kit packages
- Simpler installation clearance requirements
- A+++ efficiency class at 35 °C flow
Compliance note: All grid-connected Stiebel Eltron heat pumps require a DNO notification (G98/G99) prior to commissioning. Electrical connection must be to Part P and BS 7671. R290 units additionally require Stiebel Eltron’s clearance and ventilation requirements to be observed for the refrigerant charge size.
The four Stiebel Eltron heat pump ranges
From the value-focused Trend to the flagship WPL-A Premium platform, here is how the ranges differ — and where each one fits.
HPA-O Trend
The value-focused R290 monobloc platform — six sizes from 4.91 kW to 17.36 kW, single or three-phase, dark grey RAL 7021 finish. The best price-performance entry point into a proper German-engineered heat pump.
From £6,700
HPA-O Plus
Steps up from Trend with exceptionally quiet operation (from 43 dB(A)), A+++ efficiency across most sizes, and a choice of anthracite or white casework. Four sizes from 7.09 kW to 13.15 kW.
From £7,300
HPA-O W Plus
Same R290 platform and performance as HPA-O Plus in a factory white finish. Designed for premium new-build architecture where the outdoor unit needs to disappear against light rendered walls.
From £9,000
WPL-A Premium
Stiebel Eltron’s flagship Premium platform with R454C refrigerant, A+++ efficiency, silent night mode and the widest kit ecosystem. Delivers 6.87 kW at A-7/W35 with a SCOP of 4.88 at 35 °C flow.
From £7,500
What makes Stiebel Eltron a premium choice
Anyone can sell a monobloc air source heat pump. What distinguishes Stiebel Eltron — and justifies the specification on higher-end retrofits, developer plots, and long-life installations — is the engineering approach and the ecosystem around the unit.
German engineering, purpose-built for heat pumps
Stiebel Eltron has been engineering renewable heating since long before it was fashionable. The HPA-O and WPL-A platforms are ground-up heat pump designs — not repackaged air-conditioning tech.
Low-GWP refrigerant from launch
The whole range uses either natural R290 (GWP 3) or low-GWP R454C (GWP <150). No legacy F-gas exposure — important for long-term serviceability and future compliance.
Quiet by design
The Plus range starts at 43 dB(A) sound power — genuinely garden-friendly. WPL-A Premium includes a night silent mode. Both matter for MCS noise assessments (MCS 020) and neighbour relations.
Deep hydronic ecosystem
Matched cylinders (SBB, SBB HP Trend), integrated Heat Store & Buffer Cylinders (HSBC 220/300, HSBC S), pre-plumbed compact assemblies — every hydraulic scenario has an OEM-engineered answer.
Open integration
MyStiebel app plus Modbus and KNX give installers a real path into BMS, PV diversion and third-party smart controls — without being locked into a proprietary walled garden.
75 °C flow — genuine retrofit-ready
Some heat pumps struggle above 55 °C. Stiebel Eltron units run reliably at 75 °C, which means existing radiator circuits stay in service without wholesale rework — a huge advantage on period property retrofits.
Pre-configured Stiebel Eltron heat pump packages
For projects where installation time and hydraulic simplicity matter, Stiebel Eltron offers factory-matched sets pairing the heat pump with an OEM cylinder or integrated Heat Store, Buffer and Cylinder (HSBC) unit. Compared to hand-picking cylinder and buffer separately, the packages arrive matched for capacity, controls integration and refrigerant flow behaviour.
Understand the cylinder types first
SBB — separate DHW cylinder
A conventional heat-pump-optimised hot water cylinder (SBB 200 HP Trend, SBB 300 HP Trend, SBB 300 Trend). Sits alongside a separate buffer vessel and pump group. More flexible on siting, especially where cylinder and heat pump manager must be in different rooms.
HSBC — integrated compact unit
Heat Store, Buffer and Cylinder combined into a single floor-standing tower (HSBC 220, HSBC 300, HSBC 225 S). One cabinet contains DHW cylinder, buffer volume, pump group and hydraulic switching — ideal for utility rooms with tight floor plans.
Popular packages on our range
Trend + integrated tower
HPA-O Trend + HSBC 220
Value-tier R290 outdoor unit paired with the integrated Heat Store, Buffer and Cylinder tower. The most straightforward Trend-based install.
From £9,999
View package →Plus + integrated tower
HPA-O Plus + HSBC 220
The quieter, higher-efficiency Plus outdoor unit with the same compact HSBC 220 tower. Popular on properties where noise budget matters.
£9,999
View package →Plus + separate cylinder
HPA-O Plus + SBB 200 HP Trend
Plus outdoor unit with a 200-litre separate heat-pump cylinder — suits smaller households or where the plant room already has a buffer.
£11,300
View package →Plus + larger cylinder
HPA-O Plus + SBB 300 HP Trend
Plus outdoor unit with the 300-litre SBB HP Trend cylinder. Sized for families of 4–6 or homes with high peak draw-off across multiple bathrooms.
£12,230
View package →Trend + separate cylinder
HPA-O Trend + SBB 300 Trend
Value-tier package with a 300-litre Trend-series cylinder. A cost-effective route to a larger DHW volume without stepping up to Plus.
£13,330
View package →WPL-A Premium Compact Set
ASHP 7.5kW Premium + HSBC 225 S
The Premium WPL-A pack with the compact HSBC 225 S integrated tower. Flagship platform in its most floor-space-efficient configuration.
£9,900
View package →WPL-A Premium Pack
ASHP 7.5kW Premium + SBB 300
Premium platform with the 300-litre SBB cylinder as a separate unit — the traditional layout for homes with dedicated plant space.
£9,770
View package →WPL-A Premium Compact Pack
ASHP 7.5kW Premium + HSBC 300
Premium WPL-A with the larger HSBC 300 integrated tower for households needing more DHW capacity in a single-cabinet indoor solution.
£11,800
View package →See the full package range on our heat pump bundles collection, and browse all standalone units on the air source heat pumps page.
Model comparison at a glance
Key headline specs across the four ranges — use this to shortlist before diving into full technical data.
| Range | Refrigerant | Capacities | Output (A-7/W35) | SCOP 35°C | Sound power | Finish | Electrical |
|---|---|---|---|---|---|---|---|
| HPA-O Trend | R290 (propane) | 6 sizes | 4.91 – 17.36 kW | 4.55 – 4.69 | 44 – 52 dB(A) | Dark grey RAL 7021 | HC 230 / HC 400 |
| HPA-O Plus | R290 (propane) | 4 sizes | 7.09 – 13.15 kW | 4.89 – 5.09 | 43 – 46 dB(A) | Anthracite or white | HC 230 / HC 400 |
| HPA-O W Plus | R290 (propane) | 4 sizes | 7.09 – 13.15 kW | 4.89 – 5.09 | 43 – 46 dB(A) | White | HC 230 / HC 400 |
| WPL-A Premium | R454C (HFO) | 1 size shown | 6.87 kW | 4.88 | 48 dB(A) | White | 230V single-phase |
Sizing rule of thumb
For UK properties, 4–5 kW tends to suit compact new-builds and well-insulated flats, 7–10 kW covers most three-to-four-bedroom family homes, and 12–17 kW is territory for larger detached properties, poorly-insulated period homes running at higher flow temperatures, or small commercial buildings. That said — heat pump sizing should always be based on a proper heat loss calculation, not floor area. For anything more complex than a like-for-like replacement, we’ll run the numbers with you.
What we need to specify the right system for you
Every Stiebel Eltron installation is matched to the property. The more of the following you can share up front, the faster we can turn round a properly-costed quote — whether you’re a homeowner, an installer sizing a client’s job, or a developer standardising kit across multiple plots.
- System configuration — will the heat pump run as the sole heat source, or in a bivalent arrangement alongside an existing boiler or secondary heat source (dual-fuel)?
- Hot water demand — expected DHW usage volume for the property: occupants, bathrooms, peak draw-off patterns. Or is DHW production not required at all?
- Hydraulic layout — is the property zoned S-plan, Y-plan, or another arrangement? How many heating zones are needed?
- Pre-plumbed preference — would a pre-plumbed cylinder or HSBC assembly be preferred to reduce on-site installation time and simplify commissioning?
- Secondary return — does the property need a secondary return circulation loop for the DHW system (larger homes, long pipe runs, or premium bathrooms with rapid hot water expectations)?
- Installation restrictions — are there size or positioning restrictions for the outdoor unit, indoor cylinder, or condensate route? Any acoustic constraints from neighbouring properties?
- Electrical supply — is a single-phase (HC 230) or three-phase (HC 400) supply available? Three-phase unlocks the larger 13.15 kW and 17.36 kW outputs.
- Pump groups — how many pump groups are required downstream of the buffer on the secondary (heating distribution) side?
- Control logic — should the system be controlled by the OEM heat pump manager, or integrated with a third-party room thermostat, BMS or KNX system via Modbus?
- Heat loss data — a heat loss calculation to MCS 3005 (or equivalent) is the gold standard. If you have an EPC and floor plans, we can work from there for initial sizing.
For installers and developers: we can quote at trade specification depth — DNO paperwork guidance, MCS-compliant cylinder pairings, PCDB entries for SAP, and multi-plot standardised kits. Get in touch through the quote request form and flag your role.
About Stiebel Eltron
Founded in Germany in 1924, Stiebel Eltron has spent a century engineering water heating and, more recently, renewable energy systems. The company holds a leading position in Europe’s heat pump market with production facilities in Germany, plus additional manufacturing across Europe and Asia. Their heat pump division has been a pure-play renewables business since long before the current UK boiler transition, which shows in the depth of the hydronic ecosystem — matched cylinders, integrated HSBC compact units, controls, ISG smart gateways and open Modbus/KNX integration.
For UK homeowners, the practical result is a range that’s been proven at scale across colder European climates. For heating engineers, it’s a manufacturer with commissioning tooling, remote diagnostics, and long-term parts support. For developers and premium builders, it’s a brand that carries architectural credibility — particularly the white HPA-O W Plus and WPL-A Premium units, which are specified regularly on high-end residential schemes where the outdoor unit needs to look considered rather than tacked-on.
You can read more about the manufacturer’s air source heat pump product philosophy on Stiebel Eltron UK, and browse the whole range in our Stiebel Eltron collection.
Related buying guides and resources
New to heat pumps or comparing options? These resources go deeper on sizing, controls and hydraulic decisions:
- Heat Pump Buying Guide — sizing, refrigerant choice, and installation planning
- Heat Pumps FAQs — the questions our technical team hears most often
- Heat Pump Cylinders — standalone SBB and third-party cylinders compatible with Stiebel Eltron systems
- Pre-plumbed Heat Pump Cylinders — HSBC-style integrated compact units
- Heat Pump Buffer Tanks — when you need a separate buffer volume
- Heat Pump + Underfloor Heating Bundles — the most efficient distribution pairing
- How to meet Part L Building Regulations — useful for developers and self-builders
Ready to specify a Stiebel Eltron heat pump?
Share your property details and we’ll match you to the right range, size and cylinder pairing — usually within one working day.