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Strom 7kW Single Phase Electric System Boiler SBSP7S — No Flue Off-Grid UFH Vented Unvented Cylinder Compatible
Strom 7kW Single Phase Electric System Boiler SBSP7S — No Flue Off-Grid UFH Vented Unvented Cylinder Compatible
The Strom 7kW Single Phase Electric System Boiler is a compact, fully self-contained central heating boiler with an integrated pump, expansion vessel, and a unique multi-strand heat exchanger — designed from the ground up to be familiar to installers with experience of gas, oil, or LPG systems. It connects to an indirect hot water cylinder (vented or unvented) for domestic hot water, and circulates water around a conventional radiator or underfloor heating circuit without requiring a flue, gas supply, or annual Gas Safe inspection. Suitable for all off-gas-grid properties and for gas conversions where a flue route is not available. Fully self-modulating — the boiler steps down to as little as 1kW, reducing running costs on mild days and on time-of-use tariffs such as Economy 10. 5-year manufacturer's warranty when registered within 45 days of purchase.
⚠ Qualified Installation Required — Must be installed by a Part P registered electrician working with a qualified heating engineer. The electrical installation must comply with BS 7671 (IET Wiring Regulations) and Part P of the Building Regulations. A minimum 40A MCB and 4mm² cable are required on a dedicated circuit from the consumer unit. The boiler requires a double-pole isolation switch. Flexi hoses (¾") are recommended for the primary heating connections. Fixings are not supplied.
ℹ System Boiler — Cylinder Required for Hot Water
The Strom 7kW is a system boiler: it heats the central heating circuit and an indirect hot water cylinder for DHW. A separate hot water cylinder is required — it is not a combi boiler and does not produce instantaneous hot water. It is compatible with both vented (gravity-fed) and unvented (mains-pressure) indirect cylinders. For a complete heating and hot water solution, pair with an appropriate indirect cylinder and wiring centre for zone control.
The Strom 7kW is a system boiler: it heats the central heating circuit and an indirect hot water cylinder for DHW. A separate hot water cylinder is required — it is not a combi boiler and does not produce instantaneous hot water. It is compatible with both vented (gravity-fed) and unvented (mains-pressure) indirect cylinders. For a complete heating and hot water solution, pair with an appropriate indirect cylinder and wiring centre for zone control.
7 kW
Single phase 230V
No flue
Site anywhere
~100%
Efficient
Modulates
Down to 1kW
5-year
Warranty
Features & Benefits
✔ Multi-Strand Heat Exchanger — Self-Modulating to 1kW
Where most electric boiler competitors use a single heating element strand, the Strom uses multiple independent heating strands within a single heat exchanger unit — each strand individually controlled. This enables fully self-modulating output from as little as 1kW up to 7kW, stepping in fine increments to match demand precisely. On mild days or in well-insulated properties, the boiler runs at a fraction of its rated output rather than cycling on/off at full power — reducing electricity consumption and improving comfort stability. Modulation also reduces thermal stress on the element, extending component life.
✔ No Flue — No Gas — No Annual Safety Certificate
There are no combustion gases, no flue terminal required, and no obligation to obtain an annual Gas Safe safety certificate. The boiler can be installed in any interior location where an electrical supply can be run — kitchen, utility room, airing cupboard, or garage — regardless of proximity to an external wall. This removes the most common constraint in boiler installation and is particularly important in listed buildings, conservation areas, and flats where flue positions are restricted or prohibited by planning conditions.
✔ Integrated Pump, Expansion Vessel & Filter
The Strom system boiler contains pump, expansion vessel, and a magnetic system filter within the compact 700 × 425 × 250mm body — no separate sealed system kit, external pump, or expansion vessel is required. Compared to a heat-only boiler, this dramatically simplifies installation and reduces the number of external fittings in the airing cupboard or plant room. The integrated filter captures ferrous debris from the heating circuit, protecting the heat exchanger from sludge accumulation without requiring a separate magnetic filter to be fitted to the pipework.
✔ UFH, Radiators & Vented or Unvented Cylinders
The Strom 7kW is compatible with conventional panel radiator circuits, underfloor heating (wet), and both vented and unvented indirect hot water cylinders. The adjustable flow temperature range of 20–80°C means it can supply the lower flow temperatures required by underfloor heating manifolds (typically 35–50°C) as well as the higher temperatures needed for radiators in less well-insulated properties. A single wiring centre (S-plan or Y-plan) provides zone control between heating and hot water when combined with a cylinder thermostat and motorised zone valves.
✔ Touch Screen — Near-Silent Operation
The touch screen control panel provides direct access to flow temperature setting, operating mode selection, and system pressure display without requiring an external controller for basic operation. With minimal moving parts — the only significant moving component is the circulation pump — the Strom operates near-silently compared to gas boilers with their combustion fan, ignition sequence, and flue gas noise. This makes it suitable for installation adjacent to living areas, bedrooms, or in open-plan properties where boiler noise would be intrusive.
✔ Economy Tariff Compatible — Off-Grid Ideal
When paired with a hot water cylinder and timed on a time-of-use tariff (Economy 10, Octopus Go, Agile), the Strom 7kW system boiler is a competitive heating solution for off-grid properties that would otherwise rely on oil or LPG. The cylinder stores hot water heated during cheap-rate periods; the boiler's modulating output means the heating circuit can also be programmed to run primarily during low-rate windows. 100% renewable electricity tariffs make this the lowest carbon heating option available for off-gas-grid homes without a heat pump.
Technical Specifications — Strom 7kW Single Phase (SBSP7S)
| Manufacturer | Strom Limited (UK) |
| Model Code | SBSP7S / WBSP7S |
| Boiler Type | Electric system boiler (cylinder required for DHW) |
| Max. Heating Output | 7 kW — modulates down to 1kW |
| Supply | Single phase 230V AC, 50Hz |
| Load Current | 32A |
| Minimum MCB / Breaker | 40A |
| Minimum Cable Size | 4mm² |
| Flow Temperature Range | 20°C – 80°C (adjustable) |
| Max. System Pressure | 1.5 bar |
| Min. System Pressure | 0.5 bar |
| Heating Connections | ¾" Male BSP (flexi hoses recommended) |
| PRV Connection | 15mm compression female |
| Integral Components | Pump · expansion vessel · magnetic system filter · touch screen |
| Cylinder Compatibility | Vented indirect · unvented indirect |
| Dimensions (H × W × D) | 700 × 425 × 250 mm |
| ErP Heating Rating | D |
| Flue Required | No |
| Warranty | 5 years — must register at stromltd.com within 45 days of purchase. Defaults to 1 year if not registered. |
Frequently Asked Questions
Is 7kW enough to heat my property?
7kW is sufficient for a well-insulated property with a heat loss up to approximately 7kW — typically a 1–3 bedroom flat or smaller house. The starting point is always a heat loss calculation to BS EN 12831, which a heating engineer can carry out. As a rough rule of thumb, a modern well-insulated 2-bedroom house in England might have a heat loss of around 3–5kW, meaning the 7kW model has headroom to spare. For larger or older properties with higher heat loss, the Strom range also offers 11kW and 14.4kW single-phase models. Because the boiler is fully self-modulating, it will run efficiently even if the 7kW rating is significantly higher than the actual heat loss — it simply modulates down rather than cycling.
Does this boiler need an annual service?
Unlike gas or oil boilers, the Strom electric system boiler does not require a mandatory annual safety service — there are no combustion components, no heat exchanger flue gases, and no Carbon Monoxide risk that drives the legal servicing requirement for fossil fuel appliances. However, Strom recommend periodic maintenance checks by a qualified person — typically every two to three years — covering system pressure, expansion vessel pre-charge, filter cleaning, and a check of the electrical connections. The integrated magnetic filter should be checked and cleaned annually, and the heating system should be treated with corrosion inhibitor. Keeping Benchmark or equivalent service records is good practice and supports any warranty claim.
Can I use this with solar panels?
Yes — the Strom electric system boiler is directly compatible with solar PV systems. When the property generates more solar electricity than it consumes, a solar diverter (such as the Eddi from myenergi, or an iBoost) can redirect the surplus export to the boiler — running the heating circuit and/or charging a hot water cylinder with otherwise-wasted generation. The boiler's self-modulation is particularly useful in this context: a diverter can instruct the boiler to consume exactly the surplus available (from 1kW up to 7kW) rather than needing a fixed large load. This is one of the most effective ways to maximise self-consumption on a solar PV installation.
What is the warranty and how do I register?
The Strom 7kW system boiler carries a 5-year manufacturer's warranty, subject to registration and Strom's terms and conditions. Registration must be completed within 45 days of purchase at stromltd.com using the registration card supplied with the boiler. If the boiler is not registered within 45 days, the warranty defaults to 1 year. The 5-year warranty covers manufacturing defects in materials and workmanship. The guarantee is held by the original purchasing homeowner and is not transferable. Annual servicing records — while not strictly mandatory — will support any warranty claim and demonstrate the system has been properly maintained.
Can I replace my existing gas or oil boiler with this?
Yes — the Strom system boiler is designed to connect to existing radiator and pipework without replacement. The existing radiators, pipework, and indirect cylinder can generally remain in place. The key changes are: removing the old boiler and flue, upgrading the electrical supply to provide a dedicated 40A circuit, and potentially adding zone valve controls if not already fitted. If the existing boiler was a combi (no cylinder), a hot water cylinder will need to be added — this is a more significant installation. If the property currently has a separate cylinder (system or regular boiler setup), the changeover is straightforward. The boiler's ¾" connections match standard UK heating pipework via flexi hoses.
Is it compatible with underfloor heating?
Yes — the Strom 7kW is fully compatible with wet underfloor heating (UFH) systems. The flow temperature is adjustable down to 20°C, and typical UFH manifold supply temperatures (35–45°C for screed systems, up to 50–55°C for suspended floor systems) are well within the boiler's operating range. For mixed systems combining underfloor heating with panel radiators at different flow temperatures, a thermostatic blending valve or weather compensation control can be added to the UFH circuit. The boiler's modulating output is particularly well-suited to UFH, which responds best to stable, lower-temperature inputs rather than high-temperature on/off cycling.
$1,495.43
Strom 7kW Single Phase Electric System Boiler SBSP7S — No Flue Off-Grid UFH Vented Unvented Cylinder Compatible—
$1,495.43
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Strom 7kW Single Phase Electric System Boiler SBSP7S — No Flue Off-Grid UFH Vented Unvented Cylinder Compatible
The Strom 7kW Single Phase Electric System Boiler is a compact, fully self-contained central heating boiler with an integrated pump, expansion vessel, and a unique multi-strand heat exchanger — designed from the ground up to be familiar to installers with experience of gas, oil, or LPG systems. It connects to an indirect hot water cylinder (vented or unvented) for domestic hot water, and circulates water around a conventional radiator or underfloor heating circuit without requiring a flue, gas supply, or annual Gas Safe inspection. Suitable for all off-gas-grid properties and for gas conversions where a flue route is not available. Fully self-modulating — the boiler steps down to as little as 1kW, reducing running costs on mild days and on time-of-use tariffs such as Economy 10. 5-year manufacturer's warranty when registered within 45 days of purchase.
⚠ Qualified Installation Required — Must be installed by a Part P registered electrician working with a qualified heating engineer. The electrical installation must comply with BS 7671 (IET Wiring Regulations) and Part P of the Building Regulations. A minimum 40A MCB and 4mm² cable are required on a dedicated circuit from the consumer unit. The boiler requires a double-pole isolation switch. Flexi hoses (¾") are recommended for the primary heating connections. Fixings are not supplied.
ℹ System Boiler — Cylinder Required for Hot Water
The Strom 7kW is a system boiler: it heats the central heating circuit and an indirect hot water cylinder for DHW. A separate hot water cylinder is required — it is not a combi boiler and does not produce instantaneous hot water. It is compatible with both vented (gravity-fed) and unvented (mains-pressure) indirect cylinders. For a complete heating and hot water solution, pair with an appropriate indirect cylinder and wiring centre for zone control.
The Strom 7kW is a system boiler: it heats the central heating circuit and an indirect hot water cylinder for DHW. A separate hot water cylinder is required — it is not a combi boiler and does not produce instantaneous hot water. It is compatible with both vented (gravity-fed) and unvented (mains-pressure) indirect cylinders. For a complete heating and hot water solution, pair with an appropriate indirect cylinder and wiring centre for zone control.
7 kW
Single phase 230V
No flue
Site anywhere
~100%
Efficient
Modulates
Down to 1kW
5-year
Warranty
Features & Benefits
✔ Multi-Strand Heat Exchanger — Self-Modulating to 1kW
Where most electric boiler competitors use a single heating element strand, the Strom uses multiple independent heating strands within a single heat exchanger unit — each strand individually controlled. This enables fully self-modulating output from as little as 1kW up to 7kW, stepping in fine increments to match demand precisely. On mild days or in well-insulated properties, the boiler runs at a fraction of its rated output rather than cycling on/off at full power — reducing electricity consumption and improving comfort stability. Modulation also reduces thermal stress on the element, extending component life.
✔ No Flue — No Gas — No Annual Safety Certificate
There are no combustion gases, no flue terminal required, and no obligation to obtain an annual Gas Safe safety certificate. The boiler can be installed in any interior location where an electrical supply can be run — kitchen, utility room, airing cupboard, or garage — regardless of proximity to an external wall. This removes the most common constraint in boiler installation and is particularly important in listed buildings, conservation areas, and flats where flue positions are restricted or prohibited by planning conditions.
✔ Integrated Pump, Expansion Vessel & Filter
The Strom system boiler contains pump, expansion vessel, and a magnetic system filter within the compact 700 × 425 × 250mm body — no separate sealed system kit, external pump, or expansion vessel is required. Compared to a heat-only boiler, this dramatically simplifies installation and reduces the number of external fittings in the airing cupboard or plant room. The integrated filter captures ferrous debris from the heating circuit, protecting the heat exchanger from sludge accumulation without requiring a separate magnetic filter to be fitted to the pipework.
✔ UFH, Radiators & Vented or Unvented Cylinders
The Strom 7kW is compatible with conventional panel radiator circuits, underfloor heating (wet), and both vented and unvented indirect hot water cylinders. The adjustable flow temperature range of 20–80°C means it can supply the lower flow temperatures required by underfloor heating manifolds (typically 35–50°C) as well as the higher temperatures needed for radiators in less well-insulated properties. A single wiring centre (S-plan or Y-plan) provides zone control between heating and hot water when combined with a cylinder thermostat and motorised zone valves.
✔ Touch Screen — Near-Silent Operation
The touch screen control panel provides direct access to flow temperature setting, operating mode selection, and system pressure display without requiring an external controller for basic operation. With minimal moving parts — the only significant moving component is the circulation pump — the Strom operates near-silently compared to gas boilers with their combustion fan, ignition sequence, and flue gas noise. This makes it suitable for installation adjacent to living areas, bedrooms, or in open-plan properties where boiler noise would be intrusive.
✔ Economy Tariff Compatible — Off-Grid Ideal
When paired with a hot water cylinder and timed on a time-of-use tariff (Economy 10, Octopus Go, Agile), the Strom 7kW system boiler is a competitive heating solution for off-grid properties that would otherwise rely on oil or LPG. The cylinder stores hot water heated during cheap-rate periods; the boiler's modulating output means the heating circuit can also be programmed to run primarily during low-rate windows. 100% renewable electricity tariffs make this the lowest carbon heating option available for off-gas-grid homes without a heat pump.
Technical Specifications — Strom 7kW Single Phase (SBSP7S)
| Manufacturer | Strom Limited (UK) |
| Model Code | SBSP7S / WBSP7S |
| Boiler Type | Electric system boiler (cylinder required for DHW) |
| Max. Heating Output | 7 kW — modulates down to 1kW |
| Supply | Single phase 230V AC, 50Hz |
| Load Current | 32A |
| Minimum MCB / Breaker | 40A |
| Minimum Cable Size | 4mm² |
| Flow Temperature Range | 20°C – 80°C (adjustable) |
| Max. System Pressure | 1.5 bar |
| Min. System Pressure | 0.5 bar |
| Heating Connections | ¾" Male BSP (flexi hoses recommended) |
| PRV Connection | 15mm compression female |
| Integral Components | Pump · expansion vessel · magnetic system filter · touch screen |
| Cylinder Compatibility | Vented indirect · unvented indirect |
| Dimensions (H × W × D) | 700 × 425 × 250 mm |
| ErP Heating Rating | D |
| Flue Required | No |
| Warranty | 5 years — must register at stromltd.com within 45 days of purchase. Defaults to 1 year if not registered. |
Frequently Asked Questions
Is 7kW enough to heat my property?
7kW is sufficient for a well-insulated property with a heat loss up to approximately 7kW — typically a 1–3 bedroom flat or smaller house. The starting point is always a heat loss calculation to BS EN 12831, which a heating engineer can carry out. As a rough rule of thumb, a modern well-insulated 2-bedroom house in England might have a heat loss of around 3–5kW, meaning the 7kW model has headroom to spare. For larger or older properties with higher heat loss, the Strom range also offers 11kW and 14.4kW single-phase models. Because the boiler is fully self-modulating, it will run efficiently even if the 7kW rating is significantly higher than the actual heat loss — it simply modulates down rather than cycling.
Does this boiler need an annual service?
Unlike gas or oil boilers, the Strom electric system boiler does not require a mandatory annual safety service — there are no combustion components, no heat exchanger flue gases, and no Carbon Monoxide risk that drives the legal servicing requirement for fossil fuel appliances. However, Strom recommend periodic maintenance checks by a qualified person — typically every two to three years — covering system pressure, expansion vessel pre-charge, filter cleaning, and a check of the electrical connections. The integrated magnetic filter should be checked and cleaned annually, and the heating system should be treated with corrosion inhibitor. Keeping Benchmark or equivalent service records is good practice and supports any warranty claim.
Can I use this with solar panels?
Yes — the Strom electric system boiler is directly compatible with solar PV systems. When the property generates more solar electricity than it consumes, a solar diverter (such as the Eddi from myenergi, or an iBoost) can redirect the surplus export to the boiler — running the heating circuit and/or charging a hot water cylinder with otherwise-wasted generation. The boiler's self-modulation is particularly useful in this context: a diverter can instruct the boiler to consume exactly the surplus available (from 1kW up to 7kW) rather than needing a fixed large load. This is one of the most effective ways to maximise self-consumption on a solar PV installation.
What is the warranty and how do I register?
The Strom 7kW system boiler carries a 5-year manufacturer's warranty, subject to registration and Strom's terms and conditions. Registration must be completed within 45 days of purchase at stromltd.com using the registration card supplied with the boiler. If the boiler is not registered within 45 days, the warranty defaults to 1 year. The 5-year warranty covers manufacturing defects in materials and workmanship. The guarantee is held by the original purchasing homeowner and is not transferable. Annual servicing records — while not strictly mandatory — will support any warranty claim and demonstrate the system has been properly maintained.
Can I replace my existing gas or oil boiler with this?
Yes — the Strom system boiler is designed to connect to existing radiator and pipework without replacement. The existing radiators, pipework, and indirect cylinder can generally remain in place. The key changes are: removing the old boiler and flue, upgrading the electrical supply to provide a dedicated 40A circuit, and potentially adding zone valve controls if not already fitted. If the existing boiler was a combi (no cylinder), a hot water cylinder will need to be added — this is a more significant installation. If the property currently has a separate cylinder (system or regular boiler setup), the changeover is straightforward. The boiler's ¾" connections match standard UK heating pipework via flexi hoses.
Is it compatible with underfloor heating?
Yes — the Strom 7kW is fully compatible with wet underfloor heating (UFH) systems. The flow temperature is adjustable down to 20°C, and typical UFH manifold supply temperatures (35–45°C for screed systems, up to 50–55°C for suspended floor systems) are well within the boiler's operating range. For mixed systems combining underfloor heating with panel radiators at different flow temperatures, a thermostatic blending valve or weather compensation control can be added to the UFH circuit. The boiler's modulating output is particularly well-suited to UFH, which responds best to stable, lower-temperature inputs rather than high-temperature on/off cycling.
Product Information
Product Information
Shipping & Returns
Shipping & Returns
Description
The Strom 7kW Single Phase Electric System Boiler is a compact, fully self-contained central heating boiler with an integrated pump, expansion vessel, and a unique multi-strand heat exchanger — designed from the ground up to be familiar to installers with experience of gas, oil, or LPG systems. It connects to an indirect hot water cylinder (vented or unvented) for domestic hot water, and circulates water around a conventional radiator or underfloor heating circuit without requiring a flue, gas supply, or annual Gas Safe inspection. Suitable for all off-gas-grid properties and for gas conversions where a flue route is not available. Fully self-modulating — the boiler steps down to as little as 1kW, reducing running costs on mild days and on time-of-use tariffs such as Economy 10. 5-year manufacturer's warranty when registered within 45 days of purchase.
⚠ Qualified Installation Required — Must be installed by a Part P registered electrician working with a qualified heating engineer. The electrical installation must comply with BS 7671 (IET Wiring Regulations) and Part P of the Building Regulations. A minimum 40A MCB and 4mm² cable are required on a dedicated circuit from the consumer unit. The boiler requires a double-pole isolation switch. Flexi hoses (¾") are recommended for the primary heating connections. Fixings are not supplied.
ℹ System Boiler — Cylinder Required for Hot Water
The Strom 7kW is a system boiler: it heats the central heating circuit and an indirect hot water cylinder for DHW. A separate hot water cylinder is required — it is not a combi boiler and does not produce instantaneous hot water. It is compatible with both vented (gravity-fed) and unvented (mains-pressure) indirect cylinders. For a complete heating and hot water solution, pair with an appropriate indirect cylinder and wiring centre for zone control.
The Strom 7kW is a system boiler: it heats the central heating circuit and an indirect hot water cylinder for DHW. A separate hot water cylinder is required — it is not a combi boiler and does not produce instantaneous hot water. It is compatible with both vented (gravity-fed) and unvented (mains-pressure) indirect cylinders. For a complete heating and hot water solution, pair with an appropriate indirect cylinder and wiring centre for zone control.
7 kW
Single phase 230V
No flue
Site anywhere
~100%
Efficient
Modulates
Down to 1kW
5-year
Warranty
Features & Benefits
✔ Multi-Strand Heat Exchanger — Self-Modulating to 1kW
Where most electric boiler competitors use a single heating element strand, the Strom uses multiple independent heating strands within a single heat exchanger unit — each strand individually controlled. This enables fully self-modulating output from as little as 1kW up to 7kW, stepping in fine increments to match demand precisely. On mild days or in well-insulated properties, the boiler runs at a fraction of its rated output rather than cycling on/off at full power — reducing electricity consumption and improving comfort stability. Modulation also reduces thermal stress on the element, extending component life.
✔ No Flue — No Gas — No Annual Safety Certificate
There are no combustion gases, no flue terminal required, and no obligation to obtain an annual Gas Safe safety certificate. The boiler can be installed in any interior location where an electrical supply can be run — kitchen, utility room, airing cupboard, or garage — regardless of proximity to an external wall. This removes the most common constraint in boiler installation and is particularly important in listed buildings, conservation areas, and flats where flue positions are restricted or prohibited by planning conditions.
✔ Integrated Pump, Expansion Vessel & Filter
The Strom system boiler contains pump, expansion vessel, and a magnetic system filter within the compact 700 × 425 × 250mm body — no separate sealed system kit, external pump, or expansion vessel is required. Compared to a heat-only boiler, this dramatically simplifies installation and reduces the number of external fittings in the airing cupboard or plant room. The integrated filter captures ferrous debris from the heating circuit, protecting the heat exchanger from sludge accumulation without requiring a separate magnetic filter to be fitted to the pipework.
✔ UFH, Radiators & Vented or Unvented Cylinders
The Strom 7kW is compatible with conventional panel radiator circuits, underfloor heating (wet), and both vented and unvented indirect hot water cylinders. The adjustable flow temperature range of 20–80°C means it can supply the lower flow temperatures required by underfloor heating manifolds (typically 35–50°C) as well as the higher temperatures needed for radiators in less well-insulated properties. A single wiring centre (S-plan or Y-plan) provides zone control between heating and hot water when combined with a cylinder thermostat and motorised zone valves.
✔ Touch Screen — Near-Silent Operation
The touch screen control panel provides direct access to flow temperature setting, operating mode selection, and system pressure display without requiring an external controller for basic operation. With minimal moving parts — the only significant moving component is the circulation pump — the Strom operates near-silently compared to gas boilers with their combustion fan, ignition sequence, and flue gas noise. This makes it suitable for installation adjacent to living areas, bedrooms, or in open-plan properties where boiler noise would be intrusive.
✔ Economy Tariff Compatible — Off-Grid Ideal
When paired with a hot water cylinder and timed on a time-of-use tariff (Economy 10, Octopus Go, Agile), the Strom 7kW system boiler is a competitive heating solution for off-grid properties that would otherwise rely on oil or LPG. The cylinder stores hot water heated during cheap-rate periods; the boiler's modulating output means the heating circuit can also be programmed to run primarily during low-rate windows. 100% renewable electricity tariffs make this the lowest carbon heating option available for off-gas-grid homes without a heat pump.
Technical Specifications — Strom 7kW Single Phase (SBSP7S)
| Manufacturer | Strom Limited (UK) |
| Model Code | SBSP7S / WBSP7S |
| Boiler Type | Electric system boiler (cylinder required for DHW) |
| Max. Heating Output | 7 kW — modulates down to 1kW |
| Supply | Single phase 230V AC, 50Hz |
| Load Current | 32A |
| Minimum MCB / Breaker | 40A |
| Minimum Cable Size | 4mm² |
| Flow Temperature Range | 20°C – 80°C (adjustable) |
| Max. System Pressure | 1.5 bar |
| Min. System Pressure | 0.5 bar |
| Heating Connections | ¾" Male BSP (flexi hoses recommended) |
| PRV Connection | 15mm compression female |
| Integral Components | Pump · expansion vessel · magnetic system filter · touch screen |
| Cylinder Compatibility | Vented indirect · unvented indirect |
| Dimensions (H × W × D) | 700 × 425 × 250 mm |
| ErP Heating Rating | D |
| Flue Required | No |
| Warranty | 5 years — must register at stromltd.com within 45 days of purchase. Defaults to 1 year if not registered. |
Frequently Asked Questions
Is 7kW enough to heat my property?
7kW is sufficient for a well-insulated property with a heat loss up to approximately 7kW — typically a 1–3 bedroom flat or smaller house. The starting point is always a heat loss calculation to BS EN 12831, which a heating engineer can carry out. As a rough rule of thumb, a modern well-insulated 2-bedroom house in England might have a heat loss of around 3–5kW, meaning the 7kW model has headroom to spare. For larger or older properties with higher heat loss, the Strom range also offers 11kW and 14.4kW single-phase models. Because the boiler is fully self-modulating, it will run efficiently even if the 7kW rating is significantly higher than the actual heat loss — it simply modulates down rather than cycling.
Does this boiler need an annual service?
Unlike gas or oil boilers, the Strom electric system boiler does not require a mandatory annual safety service — there are no combustion components, no heat exchanger flue gases, and no Carbon Monoxide risk that drives the legal servicing requirement for fossil fuel appliances. However, Strom recommend periodic maintenance checks by a qualified person — typically every two to three years — covering system pressure, expansion vessel pre-charge, filter cleaning, and a check of the electrical connections. The integrated magnetic filter should be checked and cleaned annually, and the heating system should be treated with corrosion inhibitor. Keeping Benchmark or equivalent service records is good practice and supports any warranty claim.
Can I use this with solar panels?
Yes — the Strom electric system boiler is directly compatible with solar PV systems. When the property generates more solar electricity than it consumes, a solar diverter (such as the Eddi from myenergi, or an iBoost) can redirect the surplus export to the boiler — running the heating circuit and/or charging a hot water cylinder with otherwise-wasted generation. The boiler's self-modulation is particularly useful in this context: a diverter can instruct the boiler to consume exactly the surplus available (from 1kW up to 7kW) rather than needing a fixed large load. This is one of the most effective ways to maximise self-consumption on a solar PV installation.
What is the warranty and how do I register?
The Strom 7kW system boiler carries a 5-year manufacturer's warranty, subject to registration and Strom's terms and conditions. Registration must be completed within 45 days of purchase at stromltd.com using the registration card supplied with the boiler. If the boiler is not registered within 45 days, the warranty defaults to 1 year. The 5-year warranty covers manufacturing defects in materials and workmanship. The guarantee is held by the original purchasing homeowner and is not transferable. Annual servicing records — while not strictly mandatory — will support any warranty claim and demonstrate the system has been properly maintained.
Can I replace my existing gas or oil boiler with this?
Yes — the Strom system boiler is designed to connect to existing radiator and pipework without replacement. The existing radiators, pipework, and indirect cylinder can generally remain in place. The key changes are: removing the old boiler and flue, upgrading the electrical supply to provide a dedicated 40A circuit, and potentially adding zone valve controls if not already fitted. If the existing boiler was a combi (no cylinder), a hot water cylinder will need to be added — this is a more significant installation. If the property currently has a separate cylinder (system or regular boiler setup), the changeover is straightforward. The boiler's ¾" connections match standard UK heating pipework via flexi hoses.
Is it compatible with underfloor heating?
Yes — the Strom 7kW is fully compatible with wet underfloor heating (UFH) systems. The flow temperature is adjustable down to 20°C, and typical UFH manifold supply temperatures (35–45°C for screed systems, up to 50–55°C for suspended floor systems) are well within the boiler's operating range. For mixed systems combining underfloor heating with panel radiators at different flow temperatures, a thermostatic blending valve or weather compensation control can be added to the UFH circuit. The boiler's modulating output is particularly well-suited to UFH, which responds best to stable, lower-temperature inputs rather than high-temperature on/off cycling.
