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ThermoSphere Micro Electric Boiler – Instant Hot Water, 4.8–9.6kW, 5 Models, No Cylinder Required, TSMEB Series
ThermoSphere Micro Electric Boiler – Instant Hot Water, 4.8–9.6kW, 5 Models, No Cylinder Required, TSMEB Series
Instant Hot Water99.7% Efficient4.8–9.6 kWUp to 5.5 l/minA4-Sized — 315×210×120mmIP44240V Single Phase10 Bar20–60°C Temperature ControlNo Scaling / No BurnoutDual-Unit Tandem Option5-Year Warranty
The ThermoSphere Micro Electric Boiler (MEB) is an instant hot water heater and heating boiler that delivers a continuous flow of hot water at up to 60°C with 99.7% efficiency — with no cylinder, no expansion vessel and no immersion element. A patented direct energy transfer system heats the water as it flows through the unit, adjusting power output 100 times per second to maintain the exact set temperature regardless of flow rate changes — eliminating the temperature spikes and fluctuations common with conventional instantaneous heaters. Available in five output variants from 4.8 kW to 9.6 kW, with the option to install two units in tandem for up to 11 l/min combined flow. At just 315 × 210 × 120mm — the footprint of an A4 sheet of paper — it fits under sinks, in airing cupboards, loft spaces and service voids where no other water heating solution would be practical. Suitable for domestic hot water, wet UFH, solar thermal top-up and care home temperature limiting.
99.7%
Efficiency
5.5 l/m
Max Flow (single)
11 l/m
Max Flow (tandem)
60°C
Max Temperature
10 bar
Max Pressure
5 yr
Warranty
ℹ Choosing Your Model: Use the variant table below to select the right output. The key figure is your outlet flow rate in litres per minute — measure it with a 1-litre jug and a stopwatch. Match this to the flow column at +25°C temperature rise. Most UK homes with a shower will need the TSMEB-9 (9.6 kW), the most popular model. If in doubt, size up rather than down.
Select Your Variant — Single & Dual Installation
| Model | Max Output | Flow (+25°C) | MCB / Current | Supply Cable | Best For |
| TSMEB-4 | 4.8 kW | 2.8 l/min | 20A | 2.5 mm² | Lowest output — suited to hand basins and modest kitchen taps where very low flow rates (under 2.5 l/min) are typical. |
| TSMEB-6 | 6.0 kW | 3.4 l/min | 25A | 4.0 mm² | Good match for a single kitchen tap or cloakroom basin in a home with moderate mains pressure. |
| TSMEB-7 | 7.2 kW | 4.1 l/min | 30A | 4.0 mm² | Mid-range choice — handles a single shower at typical UK shower head flow rates (3.5–4 l/min). |
| TSMEB-8 | 8.4 kW | 4.8 l/min | 35A | 6.0 mm² | Comfortable single-shower option with headroom; also suitable for kitchen applications with higher flow rates. |
| TSMEB-9 ★ | 9.6 kW | 5.5 l/min | 40A | 6.0 mm² | Most popular model. Maximum single-unit output — up to 5.5 l/min at a 25°C temperature rise. |
★ Most popular model. All models: 240V, single phase. MCB ratings above are maximum load — install RCBO for circuit protection.
Dual / Tandem Installation (two units in parallel)
| Tandem Pair | Combined Output | Combined Flow | MCB per unit | Cable per unit |
| TSMEB-4 ×2 | 9.6 kW | 5.6 l/min | 20A each | 2.5 mm² each |
| TSMEB-6 ×2 | 12.0 kW | 6.8 l/min | 25A each | 4.0 mm² each |
| TSMEB-7 ×2 | 14.4 kW | 8.2 l/min | 30A each | 4.0 mm² each |
| TSMEB-8 ×2 | 16.8 kW | 9.6 l/min | 35A each | 6.0 mm² each |
| TSMEB-9 ×2 | 19.2 kW | 11.0 l/min | 40A each | 6.0 mm² each |
Each unit in a tandem pair requires its own dedicated supply circuit and RCBO.
Applications
🚿
Domestic Hot Water — Showers & Taps
Instant hot water at the tap or showerhead. The digital temperature control prevents scalding; particularly suited to care homes and assisted-living environments where water temperature must be limited to 43°C.
☀️
Solar Thermal & Heat Pump Top-Up
Acts as a 100%-efficient electric top-up when solar or heat pump output falls short — for example, on overcast days or during high demand. The heat pump runs at its optimum set point; the MEB handles the temperature shortfall.
🔥
Wet Underfloor Heating
Delivers water at the exact flow temperature required for UFH circuits — no mixing valve or buffer tank needed. Particularly useful in retrofit single-room UFH where running full heating pipework is impractical.
🏥
Temperature Limiting — Care & Commercial
Precise digital temperature limiting makes the MEB ideal for care homes, schools and commercial premises where safe hot water temperatures must be maintained consistently across all outlets.
✅ No Cylinder, No Expansion Vessel: Unlike unvented cylinders, the MEB needs only a 5 bar pressure-limiting valve and an isolating stop valve on the cold supply. Water connection is ½" BSP. Typical installation time: half a day for a qualified plumber/electrician working together.
Key Features & Technology
Patented Direct Energy Transfer — No Element, No Scale, No Burnout
The Micro Electric Boiler uses a patented direct energy transfer heating system — not a resistive wire element or immersion heater. Energy is transferred directly into the water as it flows through the unit, making it impossible to overheat, burn out or scale in the way that conventional instantaneous heaters do. There is no heating element surface that can calcify, no hot spot that can burn out, and no thermal runaway risk.
Intelligent Power Adjustment — 100 Times Per Second
An on-board microprocessor measures incoming water temperature and flow rate and adjusts power output 100 times per second to deliver the set outlet temperature regardless of changes in flow or incoming temperature. Turn on a second tap, flush a toilet — the MEB compensates instantly and the shower temperature does not spike or drop. This eliminates the temperature fluctuation that affects conventional instantaneous heaters and electric showers.
Double the Flow Rate of Conventional Instantaneous Heaters
Most instantaneous electric water heaters achieve 2.5–3 l/min at a 25°C temperature rise. The MEB delivers up to 5.5 l/min on a single unit — roughly double. For installations needing more, two units installed in tandem give up to 11 l/min — enough for a bath fill or simultaneous multi-outlet demand. Each unit in a tandem pair runs on its own dedicated circuit.
A4 Footprint — 315 × 210 × 120mm — Fits Anywhere
The MEB occupies roughly the space of a sheet of A4 paper on the wall at just 315mm tall × 210mm wide × 120mm deep, with a nominal water capacity of 385 ml. It installs directly to any wall surface using the included fixing plate, making it practical for under-sink kitchen cupboards, airing cupboards, service voids and loft spaces — wherever a cylinder or unvented unit would be impossible to accommodate.
20–60°C Digital Temperature Selection
Outlet temperature is set digitally from 20°C to 60°C in precise increments via the on-unit display. This makes the MEB particularly suitable for care homes, schools and shared accommodation where a safe maximum must be enforced — typically 43°C for care home hot water outlets — without relying on a thermostatic mixing valve.
No Expansion Vessel Required — Simplified Installation
Unlike unvented cylinders, the MEB does not require an expansion vessel. The incoming cold water supply needs only a 5 bar pressure-limiting valve and an isolating stop valve. Water connection is via a ½" BSP fitting. This dramatically reduces installation time and pipework — typically a half-day installation for a qualified electrician/plumber.
Activates at 1.5 l/min — Low Flow Rate Start
The MEB switches on automatically when flow rate reaches 1.5 litres per minute and switches off when flow stops. No manual switching required. The 385ml nominal water capacity means only a small volume of cool water is displaced at the start of a draw — hot water arrives at the outlet almost immediately after opening the tap.
5-Year Warranty — Made in the UK
ThermoSphere designs and manufactures in the UK. The MEB carries a 5-year product warranty. ThermoSphere provides installer technical support directly, including on-site commissioning assistance and a zero-callback guarantee for registered installers once the system is correctly commissioned.
Technical Specifications (ThermoSphere MEB Datasheet — 2025)
| Common Specification — All Models | |
| Output Range | 4.8 to 9.6 kW (5 models) |
| Efficiency | 99.7% |
| Switch-On Flow Rate | 1.5 litres per minute |
| Temperature Selection | 20°C to 60°C (digital) |
| Max Operating Pressure | 10 bar |
| Water Conductivity Range | 12.5 kΩ·cm to 1.2 kΩ·cm ±15% at 20°C |
| Dimensions (W × H × D) | 210 × 315 × 120 mm |
| IP Rating | IP44 |
| Voltage | 240V single phase |
| Nominal Water Capacity | 385 ml |
| Water Connection | ½" BSP (inlet and outlet) |
| Warranty | 5 years |
| Model Variants — Single Unit | |
| Model | Max Output | Flow @ +25°C | Current | MCB Size | Cable (mm²) |
| TSMEB-4 | 4.8 kW | 2.8 l/min | 20AA | 20AA RCBO | 2.5 mm² |
| TSMEB-6 | 6.0 kW | 3.4 l/min | 25AA | 25AA RCBO | 4.0 mm² |
| TSMEB-7 | 7.2 kW | 4.1 l/min | 30AA | 30AA RCBO | 4.0 mm² |
| TSMEB-8 | 8.4 kW | 4.8 l/min | 35AA | 35AA RCBO | 6.0 mm² |
| TSMEB-9 ★ | 9.6 kW | 5.5 l/min | 40AA | 40AA RCBO | 6.0 mm² |
★ Most popular model. All models 240V / single phase. Each model requires a dedicated circuit.
ℹ Installation: Fit a 5 bar pressure-limiting valve and isolating stop valve on the cold water inlet. Install an RCBO (not just an MCB) to protect the dedicated circuit. For a tandem installation, each unit requires its own independent circuit and RCBO. The MEB must be installed and commissioned by a qualified electrician and plumber. Technical support and commissioning assistance is available directly from ThermoSphere.
Frequently Asked Questions
Related Products
ThermoSphere Electric Combi Boiler
Full central heating + DHW — for properties with radiators
Wet Underfloor Heating Kits
Paired perfectly with the MEB as a compact UFH heat source
DAB VS Bronze Circulating Pump
Sanitary hot water circulation for DHWS loops
Select Output
From $431.29
Original: $1,232.25
-65%ThermoSphere Micro Electric Boiler – Instant Hot Water, 4.8–9.6kW, 5 Models, No Cylinder Required, TSMEB Series—
$1,232.25
$431.29More Images
ThermoSphere Micro Electric Boiler – Instant Hot Water, 4.8–9.6kW, 5 Models, No Cylinder Required, TSMEB Series
Instant Hot Water99.7% Efficient4.8–9.6 kWUp to 5.5 l/minA4-Sized — 315×210×120mmIP44240V Single Phase10 Bar20–60°C Temperature ControlNo Scaling / No BurnoutDual-Unit Tandem Option5-Year Warranty
The ThermoSphere Micro Electric Boiler (MEB) is an instant hot water heater and heating boiler that delivers a continuous flow of hot water at up to 60°C with 99.7% efficiency — with no cylinder, no expansion vessel and no immersion element. A patented direct energy transfer system heats the water as it flows through the unit, adjusting power output 100 times per second to maintain the exact set temperature regardless of flow rate changes — eliminating the temperature spikes and fluctuations common with conventional instantaneous heaters. Available in five output variants from 4.8 kW to 9.6 kW, with the option to install two units in tandem for up to 11 l/min combined flow. At just 315 × 210 × 120mm — the footprint of an A4 sheet of paper — it fits under sinks, in airing cupboards, loft spaces and service voids where no other water heating solution would be practical. Suitable for domestic hot water, wet UFH, solar thermal top-up and care home temperature limiting.
99.7%
Efficiency
5.5 l/m
Max Flow (single)
11 l/m
Max Flow (tandem)
60°C
Max Temperature
10 bar
Max Pressure
5 yr
Warranty
ℹ Choosing Your Model: Use the variant table below to select the right output. The key figure is your outlet flow rate in litres per minute — measure it with a 1-litre jug and a stopwatch. Match this to the flow column at +25°C temperature rise. Most UK homes with a shower will need the TSMEB-9 (9.6 kW), the most popular model. If in doubt, size up rather than down.
Select Your Variant — Single & Dual Installation
| Model | Max Output | Flow (+25°C) | MCB / Current | Supply Cable | Best For |
| TSMEB-4 | 4.8 kW | 2.8 l/min | 20A | 2.5 mm² | Lowest output — suited to hand basins and modest kitchen taps where very low flow rates (under 2.5 l/min) are typical. |
| TSMEB-6 | 6.0 kW | 3.4 l/min | 25A | 4.0 mm² | Good match for a single kitchen tap or cloakroom basin in a home with moderate mains pressure. |
| TSMEB-7 | 7.2 kW | 4.1 l/min | 30A | 4.0 mm² | Mid-range choice — handles a single shower at typical UK shower head flow rates (3.5–4 l/min). |
| TSMEB-8 | 8.4 kW | 4.8 l/min | 35A | 6.0 mm² | Comfortable single-shower option with headroom; also suitable for kitchen applications with higher flow rates. |
| TSMEB-9 ★ | 9.6 kW | 5.5 l/min | 40A | 6.0 mm² | Most popular model. Maximum single-unit output — up to 5.5 l/min at a 25°C temperature rise. |
★ Most popular model. All models: 240V, single phase. MCB ratings above are maximum load — install RCBO for circuit protection.
Dual / Tandem Installation (two units in parallel)
| Tandem Pair | Combined Output | Combined Flow | MCB per unit | Cable per unit |
| TSMEB-4 ×2 | 9.6 kW | 5.6 l/min | 20A each | 2.5 mm² each |
| TSMEB-6 ×2 | 12.0 kW | 6.8 l/min | 25A each | 4.0 mm² each |
| TSMEB-7 ×2 | 14.4 kW | 8.2 l/min | 30A each | 4.0 mm² each |
| TSMEB-8 ×2 | 16.8 kW | 9.6 l/min | 35A each | 6.0 mm² each |
| TSMEB-9 ×2 | 19.2 kW | 11.0 l/min | 40A each | 6.0 mm² each |
Each unit in a tandem pair requires its own dedicated supply circuit and RCBO.
Applications
🚿
Domestic Hot Water — Showers & Taps
Instant hot water at the tap or showerhead. The digital temperature control prevents scalding; particularly suited to care homes and assisted-living environments where water temperature must be limited to 43°C.
☀️
Solar Thermal & Heat Pump Top-Up
Acts as a 100%-efficient electric top-up when solar or heat pump output falls short — for example, on overcast days or during high demand. The heat pump runs at its optimum set point; the MEB handles the temperature shortfall.
🔥
Wet Underfloor Heating
Delivers water at the exact flow temperature required for UFH circuits — no mixing valve or buffer tank needed. Particularly useful in retrofit single-room UFH where running full heating pipework is impractical.
🏥
Temperature Limiting — Care & Commercial
Precise digital temperature limiting makes the MEB ideal for care homes, schools and commercial premises where safe hot water temperatures must be maintained consistently across all outlets.
✅ No Cylinder, No Expansion Vessel: Unlike unvented cylinders, the MEB needs only a 5 bar pressure-limiting valve and an isolating stop valve on the cold supply. Water connection is ½" BSP. Typical installation time: half a day for a qualified plumber/electrician working together.
Key Features & Technology
Patented Direct Energy Transfer — No Element, No Scale, No Burnout
The Micro Electric Boiler uses a patented direct energy transfer heating system — not a resistive wire element or immersion heater. Energy is transferred directly into the water as it flows through the unit, making it impossible to overheat, burn out or scale in the way that conventional instantaneous heaters do. There is no heating element surface that can calcify, no hot spot that can burn out, and no thermal runaway risk.
Intelligent Power Adjustment — 100 Times Per Second
An on-board microprocessor measures incoming water temperature and flow rate and adjusts power output 100 times per second to deliver the set outlet temperature regardless of changes in flow or incoming temperature. Turn on a second tap, flush a toilet — the MEB compensates instantly and the shower temperature does not spike or drop. This eliminates the temperature fluctuation that affects conventional instantaneous heaters and electric showers.
Double the Flow Rate of Conventional Instantaneous Heaters
Most instantaneous electric water heaters achieve 2.5–3 l/min at a 25°C temperature rise. The MEB delivers up to 5.5 l/min on a single unit — roughly double. For installations needing more, two units installed in tandem give up to 11 l/min — enough for a bath fill or simultaneous multi-outlet demand. Each unit in a tandem pair runs on its own dedicated circuit.
A4 Footprint — 315 × 210 × 120mm — Fits Anywhere
The MEB occupies roughly the space of a sheet of A4 paper on the wall at just 315mm tall × 210mm wide × 120mm deep, with a nominal water capacity of 385 ml. It installs directly to any wall surface using the included fixing plate, making it practical for under-sink kitchen cupboards, airing cupboards, service voids and loft spaces — wherever a cylinder or unvented unit would be impossible to accommodate.
20–60°C Digital Temperature Selection
Outlet temperature is set digitally from 20°C to 60°C in precise increments via the on-unit display. This makes the MEB particularly suitable for care homes, schools and shared accommodation where a safe maximum must be enforced — typically 43°C for care home hot water outlets — without relying on a thermostatic mixing valve.
No Expansion Vessel Required — Simplified Installation
Unlike unvented cylinders, the MEB does not require an expansion vessel. The incoming cold water supply needs only a 5 bar pressure-limiting valve and an isolating stop valve. Water connection is via a ½" BSP fitting. This dramatically reduces installation time and pipework — typically a half-day installation for a qualified electrician/plumber.
Activates at 1.5 l/min — Low Flow Rate Start
The MEB switches on automatically when flow rate reaches 1.5 litres per minute and switches off when flow stops. No manual switching required. The 385ml nominal water capacity means only a small volume of cool water is displaced at the start of a draw — hot water arrives at the outlet almost immediately after opening the tap.
5-Year Warranty — Made in the UK
ThermoSphere designs and manufactures in the UK. The MEB carries a 5-year product warranty. ThermoSphere provides installer technical support directly, including on-site commissioning assistance and a zero-callback guarantee for registered installers once the system is correctly commissioned.
Technical Specifications (ThermoSphere MEB Datasheet — 2025)
| Common Specification — All Models | |
| Output Range | 4.8 to 9.6 kW (5 models) |
| Efficiency | 99.7% |
| Switch-On Flow Rate | 1.5 litres per minute |
| Temperature Selection | 20°C to 60°C (digital) |
| Max Operating Pressure | 10 bar |
| Water Conductivity Range | 12.5 kΩ·cm to 1.2 kΩ·cm ±15% at 20°C |
| Dimensions (W × H × D) | 210 × 315 × 120 mm |
| IP Rating | IP44 |
| Voltage | 240V single phase |
| Nominal Water Capacity | 385 ml |
| Water Connection | ½" BSP (inlet and outlet) |
| Warranty | 5 years |
| Model Variants — Single Unit | |
| Model | Max Output | Flow @ +25°C | Current | MCB Size | Cable (mm²) |
| TSMEB-4 | 4.8 kW | 2.8 l/min | 20AA | 20AA RCBO | 2.5 mm² |
| TSMEB-6 | 6.0 kW | 3.4 l/min | 25AA | 25AA RCBO | 4.0 mm² |
| TSMEB-7 | 7.2 kW | 4.1 l/min | 30AA | 30AA RCBO | 4.0 mm² |
| TSMEB-8 | 8.4 kW | 4.8 l/min | 35AA | 35AA RCBO | 6.0 mm² |
| TSMEB-9 ★ | 9.6 kW | 5.5 l/min | 40AA | 40AA RCBO | 6.0 mm² |
★ Most popular model. All models 240V / single phase. Each model requires a dedicated circuit.
ℹ Installation: Fit a 5 bar pressure-limiting valve and isolating stop valve on the cold water inlet. Install an RCBO (not just an MCB) to protect the dedicated circuit. For a tandem installation, each unit requires its own independent circuit and RCBO. The MEB must be installed and commissioned by a qualified electrician and plumber. Technical support and commissioning assistance is available directly from ThermoSphere.
Frequently Asked Questions
Related Products
ThermoSphere Electric Combi Boiler
Full central heating + DHW — for properties with radiators
Wet Underfloor Heating Kits
Paired perfectly with the MEB as a compact UFH heat source
DAB VS Bronze Circulating Pump
Sanitary hot water circulation for DHWS loops
Product Information
Product Information
Shipping & Returns
Shipping & Returns
Description
Instant Hot Water99.7% Efficient4.8–9.6 kWUp to 5.5 l/minA4-Sized — 315×210×120mmIP44240V Single Phase10 Bar20–60°C Temperature ControlNo Scaling / No BurnoutDual-Unit Tandem Option5-Year Warranty
The ThermoSphere Micro Electric Boiler (MEB) is an instant hot water heater and heating boiler that delivers a continuous flow of hot water at up to 60°C with 99.7% efficiency — with no cylinder, no expansion vessel and no immersion element. A patented direct energy transfer system heats the water as it flows through the unit, adjusting power output 100 times per second to maintain the exact set temperature regardless of flow rate changes — eliminating the temperature spikes and fluctuations common with conventional instantaneous heaters. Available in five output variants from 4.8 kW to 9.6 kW, with the option to install two units in tandem for up to 11 l/min combined flow. At just 315 × 210 × 120mm — the footprint of an A4 sheet of paper — it fits under sinks, in airing cupboards, loft spaces and service voids where no other water heating solution would be practical. Suitable for domestic hot water, wet UFH, solar thermal top-up and care home temperature limiting.
99.7%
Efficiency
5.5 l/m
Max Flow (single)
11 l/m
Max Flow (tandem)
60°C
Max Temperature
10 bar
Max Pressure
5 yr
Warranty
ℹ Choosing Your Model: Use the variant table below to select the right output. The key figure is your outlet flow rate in litres per minute — measure it with a 1-litre jug and a stopwatch. Match this to the flow column at +25°C temperature rise. Most UK homes with a shower will need the TSMEB-9 (9.6 kW), the most popular model. If in doubt, size up rather than down.
Select Your Variant — Single & Dual Installation
| Model | Max Output | Flow (+25°C) | MCB / Current | Supply Cable | Best For |
| TSMEB-4 | 4.8 kW | 2.8 l/min | 20A | 2.5 mm² | Lowest output — suited to hand basins and modest kitchen taps where very low flow rates (under 2.5 l/min) are typical. |
| TSMEB-6 | 6.0 kW | 3.4 l/min | 25A | 4.0 mm² | Good match for a single kitchen tap or cloakroom basin in a home with moderate mains pressure. |
| TSMEB-7 | 7.2 kW | 4.1 l/min | 30A | 4.0 mm² | Mid-range choice — handles a single shower at typical UK shower head flow rates (3.5–4 l/min). |
| TSMEB-8 | 8.4 kW | 4.8 l/min | 35A | 6.0 mm² | Comfortable single-shower option with headroom; also suitable for kitchen applications with higher flow rates. |
| TSMEB-9 ★ | 9.6 kW | 5.5 l/min | 40A | 6.0 mm² | Most popular model. Maximum single-unit output — up to 5.5 l/min at a 25°C temperature rise. |
★ Most popular model. All models: 240V, single phase. MCB ratings above are maximum load — install RCBO for circuit protection.
Dual / Tandem Installation (two units in parallel)
| Tandem Pair | Combined Output | Combined Flow | MCB per unit | Cable per unit |
| TSMEB-4 ×2 | 9.6 kW | 5.6 l/min | 20A each | 2.5 mm² each |
| TSMEB-6 ×2 | 12.0 kW | 6.8 l/min | 25A each | 4.0 mm² each |
| TSMEB-7 ×2 | 14.4 kW | 8.2 l/min | 30A each | 4.0 mm² each |
| TSMEB-8 ×2 | 16.8 kW | 9.6 l/min | 35A each | 6.0 mm² each |
| TSMEB-9 ×2 | 19.2 kW | 11.0 l/min | 40A each | 6.0 mm² each |
Each unit in a tandem pair requires its own dedicated supply circuit and RCBO.
Applications
🚿
Domestic Hot Water — Showers & Taps
Instant hot water at the tap or showerhead. The digital temperature control prevents scalding; particularly suited to care homes and assisted-living environments where water temperature must be limited to 43°C.
☀️
Solar Thermal & Heat Pump Top-Up
Acts as a 100%-efficient electric top-up when solar or heat pump output falls short — for example, on overcast days or during high demand. The heat pump runs at its optimum set point; the MEB handles the temperature shortfall.
🔥
Wet Underfloor Heating
Delivers water at the exact flow temperature required for UFH circuits — no mixing valve or buffer tank needed. Particularly useful in retrofit single-room UFH where running full heating pipework is impractical.
🏥
Temperature Limiting — Care & Commercial
Precise digital temperature limiting makes the MEB ideal for care homes, schools and commercial premises where safe hot water temperatures must be maintained consistently across all outlets.
✅ No Cylinder, No Expansion Vessel: Unlike unvented cylinders, the MEB needs only a 5 bar pressure-limiting valve and an isolating stop valve on the cold supply. Water connection is ½" BSP. Typical installation time: half a day for a qualified plumber/electrician working together.
Key Features & Technology
Patented Direct Energy Transfer — No Element, No Scale, No Burnout
The Micro Electric Boiler uses a patented direct energy transfer heating system — not a resistive wire element or immersion heater. Energy is transferred directly into the water as it flows through the unit, making it impossible to overheat, burn out or scale in the way that conventional instantaneous heaters do. There is no heating element surface that can calcify, no hot spot that can burn out, and no thermal runaway risk.
Intelligent Power Adjustment — 100 Times Per Second
An on-board microprocessor measures incoming water temperature and flow rate and adjusts power output 100 times per second to deliver the set outlet temperature regardless of changes in flow or incoming temperature. Turn on a second tap, flush a toilet — the MEB compensates instantly and the shower temperature does not spike or drop. This eliminates the temperature fluctuation that affects conventional instantaneous heaters and electric showers.
Double the Flow Rate of Conventional Instantaneous Heaters
Most instantaneous electric water heaters achieve 2.5–3 l/min at a 25°C temperature rise. The MEB delivers up to 5.5 l/min on a single unit — roughly double. For installations needing more, two units installed in tandem give up to 11 l/min — enough for a bath fill or simultaneous multi-outlet demand. Each unit in a tandem pair runs on its own dedicated circuit.
A4 Footprint — 315 × 210 × 120mm — Fits Anywhere
The MEB occupies roughly the space of a sheet of A4 paper on the wall at just 315mm tall × 210mm wide × 120mm deep, with a nominal water capacity of 385 ml. It installs directly to any wall surface using the included fixing plate, making it practical for under-sink kitchen cupboards, airing cupboards, service voids and loft spaces — wherever a cylinder or unvented unit would be impossible to accommodate.
20–60°C Digital Temperature Selection
Outlet temperature is set digitally from 20°C to 60°C in precise increments via the on-unit display. This makes the MEB particularly suitable for care homes, schools and shared accommodation where a safe maximum must be enforced — typically 43°C for care home hot water outlets — without relying on a thermostatic mixing valve.
No Expansion Vessel Required — Simplified Installation
Unlike unvented cylinders, the MEB does not require an expansion vessel. The incoming cold water supply needs only a 5 bar pressure-limiting valve and an isolating stop valve. Water connection is via a ½" BSP fitting. This dramatically reduces installation time and pipework — typically a half-day installation for a qualified electrician/plumber.
Activates at 1.5 l/min — Low Flow Rate Start
The MEB switches on automatically when flow rate reaches 1.5 litres per minute and switches off when flow stops. No manual switching required. The 385ml nominal water capacity means only a small volume of cool water is displaced at the start of a draw — hot water arrives at the outlet almost immediately after opening the tap.
5-Year Warranty — Made in the UK
ThermoSphere designs and manufactures in the UK. The MEB carries a 5-year product warranty. ThermoSphere provides installer technical support directly, including on-site commissioning assistance and a zero-callback guarantee for registered installers once the system is correctly commissioned.
Technical Specifications (ThermoSphere MEB Datasheet — 2025)
| Common Specification — All Models | |
| Output Range | 4.8 to 9.6 kW (5 models) |
| Efficiency | 99.7% |
| Switch-On Flow Rate | 1.5 litres per minute |
| Temperature Selection | 20°C to 60°C (digital) |
| Max Operating Pressure | 10 bar |
| Water Conductivity Range | 12.5 kΩ·cm to 1.2 kΩ·cm ±15% at 20°C |
| Dimensions (W × H × D) | 210 × 315 × 120 mm |
| IP Rating | IP44 |
| Voltage | 240V single phase |
| Nominal Water Capacity | 385 ml |
| Water Connection | ½" BSP (inlet and outlet) |
| Warranty | 5 years |
| Model Variants — Single Unit | |
| Model | Max Output | Flow @ +25°C | Current | MCB Size | Cable (mm²) |
| TSMEB-4 | 4.8 kW | 2.8 l/min | 20AA | 20AA RCBO | 2.5 mm² |
| TSMEB-6 | 6.0 kW | 3.4 l/min | 25AA | 25AA RCBO | 4.0 mm² |
| TSMEB-7 | 7.2 kW | 4.1 l/min | 30AA | 30AA RCBO | 4.0 mm² |
| TSMEB-8 | 8.4 kW | 4.8 l/min | 35AA | 35AA RCBO | 6.0 mm² |
| TSMEB-9 ★ | 9.6 kW | 5.5 l/min | 40AA | 40AA RCBO | 6.0 mm² |
★ Most popular model. All models 240V / single phase. Each model requires a dedicated circuit.
ℹ Installation: Fit a 5 bar pressure-limiting valve and isolating stop valve on the cold water inlet. Install an RCBO (not just an MCB) to protect the dedicated circuit. For a tandem installation, each unit requires its own independent circuit and RCBO. The MEB must be installed and commissioned by a qualified electrician and plumber. Technical support and commissioning assistance is available directly from ThermoSphere.
Frequently Asked Questions
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