Baxi Amptec S Electric System Boiler - 4kW to 18kW Electric Central Heating
The Baxi Amptec S is a compact, UK-manufactured electric system boiler that brings the familiar look and feel of a gas boiler to homes and properties where mains gas is not an option. Available in six output sizes from 4 kW to 18 kW, with both single-phase and three-phase models, it suits everything from small flats to larger properties requiring more heating capacity. With a modulating ratio of up to 9:1, OpenTherm compatibility, and a built-in circulation pump and expansion vessel, the Amptec S is engineered to deliver genuinely efficient electric heating — and to keep installation tidy and fast.
Available as Amptec S4, S6, S8, S12, S14, and S18 — covering outputs from 4 kW to 18 kW. Single-phase models cover 4–12 kW; three-phase models cover 14 and 18 kW, giving specifiers the right fit for small flats up to larger multi-room properties.
Rather than simply switching on and off at full power, the Amptec S modulates its heating element output in a ratio of up to 9:1. This means it intelligently matches heat delivery to demand, consuming only the electricity needed and directly cutting running costs.
A wide temperature range of 35°C to 80°C makes the Amptec S equally at home driving a traditional radiator system at higher flow temperatures or an underfloor heating circuit at lower temperatures — no additional controls or settings needed to switch between system types.
Full OpenTherm compatibility allows the boiler to communicate with smart controls — including the Baxi uSense 2 — enabling weather compensation and load modulation for maximum system efficiency. OpenTherm connection unlocks better performance than a simple on/off thermostat connection.
The Amptec S ships with a built-in circulation pump and 7-litre expansion vessel. These components are housed within the boiler casing, reducing pipework, cutting installation time, and keeping the plant space tidy — all pipework connections are contained inside the unit.
At just 284 mm deep, the Amptec S fits comfortably inside a standard 290 mm deep cupboard. Weighing between 20 and 22.5 kg empty depending on model, it is light enough for one person to handle safely, making installation easier in tight or awkward spaces.
Duty cycling rotates which heating elements are active, distributing wear evenly across all elements. This extends the working life of each element, improves long-term reliability, and helps maintain consistent thermal efficiency across the product's lifespan.
For properties without mains gas — rural homes, older buildings with flue restrictions, flats, garages, or extensions — the Amptec S is a cleaner, safer alternative to LPG. No fuel deliveries, no storage tanks, no flue penetrations. Just a reliable electric heating solution.
The Amptec S can be used in conjunction with a Solar PV battery system, allowing homeowners to use self-generated renewable electricity to run the boiler and directly offset running costs — making it a strong choice for homes with existing or planned solar installations.
| Specification | S4 | S6 | S8 | S12 | S14 | S18 |
|---|---|---|---|---|---|---|
| Product Code | 7828706 | 7828707 | 7828708 | 7828710 | 7828711 | 7828712 |
| Phase | Single Phase (230 V) | Three Phase (400 V) | ||||
| Max output (kW) | 4 | 6 | 8 | 12 | 14 | 18 |
| Weight empty (kg) | 20 | 20 | 21.5 | 21.5 | 22.5 | 22.5 |
| Weight full (kg) | 21 | 21 | 23 | 23 | 24.5 | 24.5 |
| Internal volume (litres) | 1 | 1 | 1.5 | 1.5 | 2 | 2 |
| Expansion vessel (litres) | 7 (all models) | |||||
| Temperature range | 35–80°C (all models) | |||||
| Min / Max heating pressure (bar) | 0.5 / 2.8 (all models) | |||||
| PRV setting (bar) | 2.8 (all models) | |||||
| Supply voltage | 230 V / 50 Hz | 400 V 3-ph / 50 Hz | ||||
| Power consumption (W) | 4,060 | 6,060 | 8,060 | 12,060 | 14,060 | 18,060 |
| Internal MCB (elements) | 10 A × 3 | 20 A × 3 | 32 A × 3 | 32 A × 4 | ||
| Pipe connections (flow & return) | 22 mm (all models) | |||||
Which Amptec S model is right for my property?
Output sizing depends on the heat loss of the property. As a rough guide, 4–6 kW suits smaller flats or well-insulated properties; 8–12 kW suits typical 2–3 bedroom homes; and 14–18 kW (three-phase) suits larger properties with higher heat demand. A heat loss calculation by a qualified engineer will give you an accurate answer. Note that S14 and S18 models require a three-phase 400 V supply.
Does the Amptec S provide hot water as well as heating?
No. The Amptec S is a system boiler and provides central heating only. To supply domestic hot water you will need a separate indirect hot water cylinder. The boiler heats the cylinder's coil, which in turn heats the stored water. This is a standard and straightforward arrangement for system boiler installations.
Is the Amptec S suitable for underfloor heating?
Yes. The adjustable temperature range of 35°C to 80°C means the Amptec S can operate at the low flow temperatures typically required for underfloor heating (usually 35–45°C) as well as the higher temperatures needed for standard radiator systems. No additional low-loss header or blending valve is required for typical UFH circuits, though system design will dictate the exact configuration.
What does OpenTherm compatibility mean in practice?
OpenTherm is a communication standard that allows a smart thermostat — such as the Baxi uSense 2 — to send temperature demand information directly to the boiler rather than simply switching it on or off. This enables the Amptec S to modulate its output precisely to match the demand, avoiding over-heating and reducing electricity consumption. An OpenTherm-connected system will typically be more efficient than a standard on/off thermostat installation.
Does the Amptec S need an annual service?
Electric boilers generally require less routine maintenance than gas boilers. There is no annual gas safety certificate requirement, no combustion analysis, and no flue inspection. Baxi recommends a periodic check by a qualified engineer to inspect electrical connections, system pressure, and the condition of the heating water — but the service requirements are significantly lighter than for gas or oil appliances.
Can the Amptec S work with a Solar PV or battery system?
Yes. The Amptec S is compatible with use alongside a Solar PV battery system. By diverting surplus solar-generated electricity to run the boiler, homeowners can reduce the amount of grid electricity consumed for heating — directly lowering running costs. This makes the Amptec S a particularly strong choice for properties with existing solar installations or those planning to add renewables in the future.
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Baxi Amptec S Electric System Boiler - 4kW to 18kW Electric Central Heating
The Baxi Amptec S is a compact, UK-manufactured electric system boiler that brings the familiar look and feel of a gas boiler to homes and properties where mains gas is not an option. Available in six output sizes from 4 kW to 18 kW, with both single-phase and three-phase models, it suits everything from small flats to larger properties requiring more heating capacity. With a modulating ratio of up to 9:1, OpenTherm compatibility, and a built-in circulation pump and expansion vessel, the Amptec S is engineered to deliver genuinely efficient electric heating — and to keep installation tidy and fast.
Available as Amptec S4, S6, S8, S12, S14, and S18 — covering outputs from 4 kW to 18 kW. Single-phase models cover 4–12 kW; three-phase models cover 14 and 18 kW, giving specifiers the right fit for small flats up to larger multi-room properties.
Rather than simply switching on and off at full power, the Amptec S modulates its heating element output in a ratio of up to 9:1. This means it intelligently matches heat delivery to demand, consuming only the electricity needed and directly cutting running costs.
A wide temperature range of 35°C to 80°C makes the Amptec S equally at home driving a traditional radiator system at higher flow temperatures or an underfloor heating circuit at lower temperatures — no additional controls or settings needed to switch between system types.
Full OpenTherm compatibility allows the boiler to communicate with smart controls — including the Baxi uSense 2 — enabling weather compensation and load modulation for maximum system efficiency. OpenTherm connection unlocks better performance than a simple on/off thermostat connection.
The Amptec S ships with a built-in circulation pump and 7-litre expansion vessel. These components are housed within the boiler casing, reducing pipework, cutting installation time, and keeping the plant space tidy — all pipework connections are contained inside the unit.
At just 284 mm deep, the Amptec S fits comfortably inside a standard 290 mm deep cupboard. Weighing between 20 and 22.5 kg empty depending on model, it is light enough for one person to handle safely, making installation easier in tight or awkward spaces.
Duty cycling rotates which heating elements are active, distributing wear evenly across all elements. This extends the working life of each element, improves long-term reliability, and helps maintain consistent thermal efficiency across the product's lifespan.
For properties without mains gas — rural homes, older buildings with flue restrictions, flats, garages, or extensions — the Amptec S is a cleaner, safer alternative to LPG. No fuel deliveries, no storage tanks, no flue penetrations. Just a reliable electric heating solution.
The Amptec S can be used in conjunction with a Solar PV battery system, allowing homeowners to use self-generated renewable electricity to run the boiler and directly offset running costs — making it a strong choice for homes with existing or planned solar installations.
| Specification | S4 | S6 | S8 | S12 | S14 | S18 |
|---|---|---|---|---|---|---|
| Product Code | 7828706 | 7828707 | 7828708 | 7828710 | 7828711 | 7828712 |
| Phase | Single Phase (230 V) | Three Phase (400 V) | ||||
| Max output (kW) | 4 | 6 | 8 | 12 | 14 | 18 |
| Weight empty (kg) | 20 | 20 | 21.5 | 21.5 | 22.5 | 22.5 |
| Weight full (kg) | 21 | 21 | 23 | 23 | 24.5 | 24.5 |
| Internal volume (litres) | 1 | 1 | 1.5 | 1.5 | 2 | 2 |
| Expansion vessel (litres) | 7 (all models) | |||||
| Temperature range | 35–80°C (all models) | |||||
| Min / Max heating pressure (bar) | 0.5 / 2.8 (all models) | |||||
| PRV setting (bar) | 2.8 (all models) | |||||
| Supply voltage | 230 V / 50 Hz | 400 V 3-ph / 50 Hz | ||||
| Power consumption (W) | 4,060 | 6,060 | 8,060 | 12,060 | 14,060 | 18,060 |
| Internal MCB (elements) | 10 A × 3 | 20 A × 3 | 32 A × 3 | 32 A × 4 | ||
| Pipe connections (flow & return) | 22 mm (all models) | |||||
Which Amptec S model is right for my property?
Output sizing depends on the heat loss of the property. As a rough guide, 4–6 kW suits smaller flats or well-insulated properties; 8–12 kW suits typical 2–3 bedroom homes; and 14–18 kW (three-phase) suits larger properties with higher heat demand. A heat loss calculation by a qualified engineer will give you an accurate answer. Note that S14 and S18 models require a three-phase 400 V supply.
Does the Amptec S provide hot water as well as heating?
No. The Amptec S is a system boiler and provides central heating only. To supply domestic hot water you will need a separate indirect hot water cylinder. The boiler heats the cylinder's coil, which in turn heats the stored water. This is a standard and straightforward arrangement for system boiler installations.
Is the Amptec S suitable for underfloor heating?
Yes. The adjustable temperature range of 35°C to 80°C means the Amptec S can operate at the low flow temperatures typically required for underfloor heating (usually 35–45°C) as well as the higher temperatures needed for standard radiator systems. No additional low-loss header or blending valve is required for typical UFH circuits, though system design will dictate the exact configuration.
What does OpenTherm compatibility mean in practice?
OpenTherm is a communication standard that allows a smart thermostat — such as the Baxi uSense 2 — to send temperature demand information directly to the boiler rather than simply switching it on or off. This enables the Amptec S to modulate its output precisely to match the demand, avoiding over-heating and reducing electricity consumption. An OpenTherm-connected system will typically be more efficient than a standard on/off thermostat installation.
Does the Amptec S need an annual service?
Electric boilers generally require less routine maintenance than gas boilers. There is no annual gas safety certificate requirement, no combustion analysis, and no flue inspection. Baxi recommends a periodic check by a qualified engineer to inspect electrical connections, system pressure, and the condition of the heating water — but the service requirements are significantly lighter than for gas or oil appliances.
Can the Amptec S work with a Solar PV or battery system?
Yes. The Amptec S is compatible with use alongside a Solar PV battery system. By diverting surplus solar-generated electricity to run the boiler, homeowners can reduce the amount of grid electricity consumed for heating — directly lowering running costs. This makes the Amptec S a particularly strong choice for properties with existing solar installations or those planning to add renewables in the future.
Product Information
Product Information
Shipping & Returns
Shipping & Returns
Description
The Baxi Amptec S is a compact, UK-manufactured electric system boiler that brings the familiar look and feel of a gas boiler to homes and properties where mains gas is not an option. Available in six output sizes from 4 kW to 18 kW, with both single-phase and three-phase models, it suits everything from small flats to larger properties requiring more heating capacity. With a modulating ratio of up to 9:1, OpenTherm compatibility, and a built-in circulation pump and expansion vessel, the Amptec S is engineered to deliver genuinely efficient electric heating — and to keep installation tidy and fast.
Available as Amptec S4, S6, S8, S12, S14, and S18 — covering outputs from 4 kW to 18 kW. Single-phase models cover 4–12 kW; three-phase models cover 14 and 18 kW, giving specifiers the right fit for small flats up to larger multi-room properties.
Rather than simply switching on and off at full power, the Amptec S modulates its heating element output in a ratio of up to 9:1. This means it intelligently matches heat delivery to demand, consuming only the electricity needed and directly cutting running costs.
A wide temperature range of 35°C to 80°C makes the Amptec S equally at home driving a traditional radiator system at higher flow temperatures or an underfloor heating circuit at lower temperatures — no additional controls or settings needed to switch between system types.
Full OpenTherm compatibility allows the boiler to communicate with smart controls — including the Baxi uSense 2 — enabling weather compensation and load modulation for maximum system efficiency. OpenTherm connection unlocks better performance than a simple on/off thermostat connection.
The Amptec S ships with a built-in circulation pump and 7-litre expansion vessel. These components are housed within the boiler casing, reducing pipework, cutting installation time, and keeping the plant space tidy — all pipework connections are contained inside the unit.
At just 284 mm deep, the Amptec S fits comfortably inside a standard 290 mm deep cupboard. Weighing between 20 and 22.5 kg empty depending on model, it is light enough for one person to handle safely, making installation easier in tight or awkward spaces.
Duty cycling rotates which heating elements are active, distributing wear evenly across all elements. This extends the working life of each element, improves long-term reliability, and helps maintain consistent thermal efficiency across the product's lifespan.
For properties without mains gas — rural homes, older buildings with flue restrictions, flats, garages, or extensions — the Amptec S is a cleaner, safer alternative to LPG. No fuel deliveries, no storage tanks, no flue penetrations. Just a reliable electric heating solution.
The Amptec S can be used in conjunction with a Solar PV battery system, allowing homeowners to use self-generated renewable electricity to run the boiler and directly offset running costs — making it a strong choice for homes with existing or planned solar installations.
| Specification | S4 | S6 | S8 | S12 | S14 | S18 |
|---|---|---|---|---|---|---|
| Product Code | 7828706 | 7828707 | 7828708 | 7828710 | 7828711 | 7828712 |
| Phase | Single Phase (230 V) | Three Phase (400 V) | ||||
| Max output (kW) | 4 | 6 | 8 | 12 | 14 | 18 |
| Weight empty (kg) | 20 | 20 | 21.5 | 21.5 | 22.5 | 22.5 |
| Weight full (kg) | 21 | 21 | 23 | 23 | 24.5 | 24.5 |
| Internal volume (litres) | 1 | 1 | 1.5 | 1.5 | 2 | 2 |
| Expansion vessel (litres) | 7 (all models) | |||||
| Temperature range | 35–80°C (all models) | |||||
| Min / Max heating pressure (bar) | 0.5 / 2.8 (all models) | |||||
| PRV setting (bar) | 2.8 (all models) | |||||
| Supply voltage | 230 V / 50 Hz | 400 V 3-ph / 50 Hz | ||||
| Power consumption (W) | 4,060 | 6,060 | 8,060 | 12,060 | 14,060 | 18,060 |
| Internal MCB (elements) | 10 A × 3 | 20 A × 3 | 32 A × 3 | 32 A × 4 | ||
| Pipe connections (flow & return) | 22 mm (all models) | |||||
Which Amptec S model is right for my property?
Output sizing depends on the heat loss of the property. As a rough guide, 4–6 kW suits smaller flats or well-insulated properties; 8–12 kW suits typical 2–3 bedroom homes; and 14–18 kW (three-phase) suits larger properties with higher heat demand. A heat loss calculation by a qualified engineer will give you an accurate answer. Note that S14 and S18 models require a three-phase 400 V supply.
Does the Amptec S provide hot water as well as heating?
No. The Amptec S is a system boiler and provides central heating only. To supply domestic hot water you will need a separate indirect hot water cylinder. The boiler heats the cylinder's coil, which in turn heats the stored water. This is a standard and straightforward arrangement for system boiler installations.
Is the Amptec S suitable for underfloor heating?
Yes. The adjustable temperature range of 35°C to 80°C means the Amptec S can operate at the low flow temperatures typically required for underfloor heating (usually 35–45°C) as well as the higher temperatures needed for standard radiator systems. No additional low-loss header or blending valve is required for typical UFH circuits, though system design will dictate the exact configuration.
What does OpenTherm compatibility mean in practice?
OpenTherm is a communication standard that allows a smart thermostat — such as the Baxi uSense 2 — to send temperature demand information directly to the boiler rather than simply switching it on or off. This enables the Amptec S to modulate its output precisely to match the demand, avoiding over-heating and reducing electricity consumption. An OpenTherm-connected system will typically be more efficient than a standard on/off thermostat installation.
Does the Amptec S need an annual service?
Electric boilers generally require less routine maintenance than gas boilers. There is no annual gas safety certificate requirement, no combustion analysis, and no flue inspection. Baxi recommends a periodic check by a qualified engineer to inspect electrical connections, system pressure, and the condition of the heating water — but the service requirements are significantly lighter than for gas or oil appliances.
Can the Amptec S work with a Solar PV or battery system?
Yes. The Amptec S is compatible with use alongside a Solar PV battery system. By diverting surplus solar-generated electricity to run the boiler, homeowners can reduce the amount of grid electricity consumed for heating — directly lowering running costs. This makes the Amptec S a particularly strong choice for properties with existing solar installations or those planning to add renewables in the future.
