The Sunamp Thermino ePlus is a direct electric heat battery — a compact, mains-pressure hot water system that replaces a traditional hot water cylinder. Using Plentigrade P58 phase change material (PCM), it stores thermal energy far more densely than water, making it up to 4× smaller than the cylinder it replaces. Available in four sizes — 70, 150, 210 and 300 (litre equivalents) — covering single-bedroom flats through to 4+ bedroom homes. Charged by a 2,800W electric heating element directly from the mains, it can exploit off-peak electricity tariffs and be upgraded for solar PV diversion at any time by adding the Optimino ePV key — no new unit required. Mains-pressure hot water on demand with V40 outputs from 105 to 436 litres. No mandatory annual servicing. 10-year warranty on heating element and PCM core. Designed and manufactured in Scotland, UK.
Up to 4×
Smaller Than Cylinder
2,800W
Heating Element
105–436 L
V40 Output
10 yr
Warranty
Off-Peak
Tariff Ready
Solar PV
Optimino Key
Thermino ePlus Model Range — Technical Data
Model
Part Number
Equiv. Cylinder (L)
V40 (L)
Max Flow (L/min)
Heat Loss (kWh/24h)
Energy Class
Weight Filled (kg)
Height (mm)
70 ePlus
SGP-KNW-AVZ-1
74
105
6
0.48 (20W)
C
79
440
150 ePlus
SKP-KNW-AVZ-1
140
199
15
0.67 (28.1W)
C
140
640
210 ePlus
SNP-KNW-AVZ-1
212
301
20
0.77 (32.1W)
C
178
870
300 ePlus
DRP-KNW-AVY-1
306
436
25
0.84 (34.9W)
C
233
1050
All models: Width 365mm × Depth 575mm. V40 = volume of hot water available at 40°C. Heating element: 2,800W at 230V/50Hz. Minimum mains supply pressure: 1.5 bar. Maximum working pressure: 5 bar. Recommended TMV setting: 45–55°C. Annual electricity consumption (AEC): 542 / 1,398 / 2,690 / 2,701 kWh/annum.
⚠ Scald Prevention: In line with UK Building Regulations, Sunamp requires a thermostatic mixing valve (TMV) to be fitted at the outlet of the heat battery, set to deliver hot water at 45–55°C. The PCM stores energy at temperatures that can cause severe burns if delivered unmixed directly to outlets.
Key Features
Plentigrade PCM — Up to 4× Smaller Than the Cylinder It Replaces
The Thermino ePlus stores thermal energy in Plentigrade P58 — Sunamp's patented phase change material (PCM). PCM stores latent heat as it transitions between solid and liquid states at 58°C, delivering far more energy per litre than water-based storage. The result: Thermino ePlus is up to 4× smaller than the equivalent hot water cylinder, freeing up significant space in kitchens, utility rooms and service cupboards.
Plentigrade P58 PCMUp to 4× smallerMade in UK
Direct Electric Heating — Grid, Off-Peak and Solar PV Ready
The ePlus is a direct electric heat battery — charged by a built-in 2,800W immersion element connected directly to the mains. Connect to an off-peak electricity tariff (Economy 7, Agile etc.) to charge at night at lower rates. Add solar PV diversion at any time by fitting the Optimino ePV key — no new unit required. Compatible with power diverters including myenergi eddi.
Direct electricOff-peak tariffSolar PV via Optimino key
Optimino Keys — Future-Proof in Stages
The Optimino key system allows the ePlus to evolve with your energy setup without replacing the heat battery. Start with grid electricity; later add the Optimino ePV key to divert solar PV generation to the unit. This staged upgrade path means you are never locked into a fixed configuration.
Optimino ePV keyUpgradeable in stages
Mains-Pressure Hot Water — On Demand
Delivers mains-pressure hot water instantly on demand — no waiting for a tank to reheat. V40 output ranges from 105 litres (70 model) to 436 litres (300 model) at 40°C, covering 1-bedroom apartments through to 4+ bedroom homes. Maximum flow rates from 6 l/min (70) to 25 l/min (300) — suitable for multiple simultaneous outlets.
Mains pressure105–436 L at 40°CInstant delivery
Ultra-Low Heat Loss — No Annual Servicing Required
Heat loss rates of just 0.48 kWh/24h (70 model) to 0.84 kWh/24h (300 model) — significantly lower than conventional hot water cylinders. No mandatory annual maintenance is required. The unit contains no user-serviceable parts and requires no access to the PCM container in the field.
Ultra-low heat lossNo annual service
Modular and Scalable — Series or Parallel Connection
Multiple Thermino ePlus units can be connected in series or parallel to increase storage capacity and flow rate for higher-demand installations without requiring larger pipework runs.
ModularSeries / parallelScalable
Flexible Pipe Access — Three Sides
Pipe and cable entries on three sides (rear, left, right) give installers the flexibility to route connections in the most convenient direction for the installation, reducing the need for awkward bends.
3-side accessFlexible installation
10-Year Warranty on Heating Element
Sunamp provides a market-leading 10-year warranty on the heating element and storage core (Plentigrade P58 PCM) for products purchased and installed in the UK. The warranty is registered online at the time of installation.
10-year warrantyElement + PCM core
Technical Specifications
Electrical
Heating Element Capacity
2,800W at 230V / 50Hz (1,800W low-power model also available)
10 years (UK purchase and installation, online registration)
No Annual Service Required
Yes — no mandatory maintenance
Country of Origin
United Kingdom (Macmerry, East Lothian)
ℹ Installation: Must be installed by a qualified and competent person. Always refer to the manufacturer's latest installation manual. In line with UK Building Regulations, a thermostatic mixing valve (TMV) must be fitted at the outlet of all Thermino heat batteries to prevent scalding.
Frequently Asked Questions
What is the difference between the ePlus 70, 150, 210 and 300?
The models differ in thermal storage capacity and V40 hot water output: 70 (105 L at 40°C, 6 l/min max — 1-bed home or flat); 150 (199 L at 40°C, 15 l/min — 1 to 2-bed home); 210 (301 L at 40°C, 20 l/min — 3-bed home); 300 (436 L at 40°C, 25 l/min — 4+ bed home). All share the same footprint (365 × 575mm) — only height varies.
Can I add solar PV later without buying a new unit?
Yes — the ePlus is designed to be future-proofed. Fit the Optimino ePV key at any point after installation to enable solar PV diversion. No new heat battery is needed. Compatible power diverters include myenergi eddi and others listed on Sunamp's Optimino resources page.
Is the ePlus suitable for tank-fed systems?
No — the Thermino ePlus is not suitable for tank-fed hot water systems. The property must have a mains-pressurised cold water supply. Tank-fed systems must be converted to mains pressure before installation.
What is V40 and how does it relate to my hot water needs?
V40 is the volume of hot water deliverable at 40°C from a single charge. A 150 ePlus delivers 199 litres at 40°C — comparable to a 140-litre hot water cylinder. A 210 ePlus delivers 301 litres. For a 3-bed home with typical demand, the 210 is generally recommended.
What happens in hard water areas?
Where mains water hardness exceeds 150 ppm, Sunamp requires a scale-reducing device in the cold-water supply to the heat battery. Options include polyphosphate dosers, electrolytic scale reducers or water softeners. The Sunamp water conditioner (C5381) is the recommended accessory for this purpose.
Related Products
Sunamp Thermino xPlus Heat Battery
Indirect — for boilers and heat pumps
Sunamp A2057 Installation Kit
PRV, TMV, expansion vessel — required accessories
Solar iBoost+ Immersion Controller
Divert surplus PV to immersion/heat battery
myenergi eddi Solar Diverter
Compatible PV diverter for Optimino ePV key
BTU & WATT Calculator
Room Dimensions
Room Type
Living Room
Bedroom
Kitchen
Bathroom
Conservatory
Hallway
Glazing Type
Single Glazed
Double Glazed
Triple Glazed
External Walls
0 Wall
1 Wall
2 Walls
3 Walls
4 Walls
Insulation Level
Poor
Average
Good (New Build)
Required Heating
0
Watts
0
BTUs
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