The Biasi Pro-Electric 25kW Three-Phase Combi Boiler with Combi Fittings Pack (model BIPROELEC25C) is the highest-output boiler in Biasi UK’s electric range — designed as a direct drop-in replacement for a gas combi boiler in larger homes with multiple bathrooms, high hot water demand or bath filling requirements. It delivers a continuous 12 L/min of hot water on demand and provides central heating compatible with existing radiators and underfloor heating, all without a flue, without gas, and without any combustion whatsoever. The boiler operates on a 400V three-phase 50Hz supply at 36A, requiring a 40A breaker and 3 × 6 mm² cable. Power modulates from 2kW to the full 25kW to match actual heating demand, at near-100% conversion efficiency. At just 15 dB(A), it is virtually inaudible in operation. Dimensions: 630 × 380 × 230 mm, ~25 kg. This package includes the boiler, installation manual, mounting hardware, and the Biasi Combi Fittings Pack (Ei1124500) — full-bore service valves and automatic bypass valve. Three-year warranty (register within 45 days, annual electrical service required).
25kW
Output
12 L/min
Hot Water
400V 3Φ
Supply
15 dB
Sound Level
3-yr
Warranty
Near 100%
Efficient
What’s Included
Biasi Pro-Electric 25kW Combi Boiler (3-phase)
Model BIPROELEC25C. Wall-mounted, pre-wired, with built-in pump and 6L expansion vessel.
Biasi Combi Fittings Pack (Ei1124500)
Full-bore service valves, automatic bypass valve (ABV) — everything needed for a clean installation.
Biasi Pro-Electric installation manual with commissioning checklist.
ℹ Filling loop note: Biasi does not recommend a filling loop for this boiler. The system should be filled and pressurised via an alternative method approved by your installer. Consult the installation manual and your system designer.
Three-Phase Electrical Requirements
25kW three-phase (400V 3N∼) supply requirements
Supply voltage: 400V three-phase 50Hz (3N∼) Current draw: 36A Recommended breaker (MCB/RCD): 40A Minimum cable size: 3 × 6 mm² copper core Leakage protection switch: ≥50A Wiring: L1, L2, L3, N and Earth — 4+E configuration Part P certificate: Required immediately after live connection. Must be issued by a registered electrician. Warranty registration: Within 45 days of purchase at biasi.co.uk
⚠ Three-phase supply required: This boiler requires a 400V three-phase (3N∼) supply. It is not compatible with standard single-phase 230V domestic wiring. Verify that a suitable three-phase supply is available at the property before ordering. Wiring must be carried out by a qualified electrician to BS 7671; a Part P certificate must be issued. Annual service by a registered electrician is required to maintain the warranty.
Key Features
25kW Output — Sized for Larger Homes, Multiple Bathrooms and Bath Filling
At 25kW, this is the highest-output electric combi boiler in the Biasi Pro-Electric range. It delivers a continuous hot water flow rate of up to 12 L/min — enough to fill a bath at a usable temperature, supply a power shower, or run multiple outlets simultaneously. The 25kW output also provides the heating capacity for larger homes with four or more bedrooms, multiple bathrooms or higher heat-loss properties. It replaces a gas combi boiler directly, using the same pipework and radiator circuit.
25kW12 L/min DHWBath filling4+ bedroom homes
Three-Phase 400V Supply — Unlocks the Full 25kW Rating
The 20kW and 25kW outputs of the Biasi Pro-Electric range require a 400V three-phase supply. Single-phase 230V electrical circuits cannot physically supply 25kW continuously — a 25kW single-phase load would require approximately 109A, which exceeds standard domestic metering. Three-phase distribution spreads the load across three phases at approximately 36A per phase, within standard three-phase supply infrastructure. This boiler is therefore specifically suited to properties that already have a three-phase supply, or where one is being installed as part of a broader electrical upgrade.
400V 3-phase36A per phase3 × 6mm² cable40A breaker
Power Modulates from 2kW to Full 25kW — Near-100% Efficiency
The Biasi Pro-Electric modulates output from a minimum of 2kW up to the full 25kW. In mild weather, the boiler runs at reduced power to match the actual heat loss of the building, rather than cycling on and off at full power. Electric resistance heating converts electricity to heat at near-100% efficiency (there are no flue losses, no condensation cycle and no standby pilot flame). This is in contrast to gas boilers, which — even at rated efficiency — lose heat through the flue and condensate circuit.
Drop-In Replacement for Gas Combi Boilers — Same Pipework and Radiators
The Pro-Electric uses the same flow and return connections as a gas combi boiler (¾″ male heating, ½″ male hot water). It can be connected directly to existing pipework and radiator circuits without modification. The built-in pump, expansion vessel (6L), safety valve and pressure gauge are all pre-fitted — the installation is no more complex than replacing one combi with another. No flue, no gas connection, no combustion air requirements.
Same connections as gas combiExisting pipework compatibleNo flue needed
No Flue Required — Install Anywhere in the Property
As an electric boiler, the Pro-Electric produces no combustion gases and requires no flue whatsoever. This means it can be sited in any location that meets the physical and electrical access requirements: kitchen, utility room, airing cupboard, loft, basement or any other indoor location. There are no flue route restrictions, no minimum clearance from windows or doors, and no requirement for room ventilation for combustion air.
No flueNo gasNo CO riskInstall anywhere indoors
Touchscreen Controls — Radiator and Underfloor Heating Modes
The digital touchscreen allows adjustment of flow temperature from 30°C to 80°C for radiator mode, or 30°C to 60°C for underfloor heating mode. Summer and winter modes allow hot water only or combined heating and hot water. A 24-hour timer, child lock, anti-freeze function and fault code display are all built in. Room thermostat input for external control is supported.
The Pro-Electric measures just 15 dB(A) in operation — quieter than a whisper (which is approximately 30 dB). There is no combustion, no fan, no gas valve noise and no condensate gurgling. The only moving part is the circulating pump. This makes it suitable for installation in bedrooms, living rooms and open-plan spaces without noise disruption.
15 dB(A)Near-silentNo combustion noise
Three-Year Warranty — Register Within 45 Days
Biasi UK provides a three-year warranty on the Pro-Electric range (excluding damage from human error, natural causes or non-compliance with installation requirements). Warranty activation requires: (1) registration within 45 days of purchase at biasi.co.uk; (2) a Part P electrical certificate issued at installation; (3) annual service by a registered electrician.
3-year warrantyRegister within 45 daysAnnual service required
Combi Fittings Pack Included (Ei1124500) — Everything for a Complete Installation
This bundle includes the Biasi Pro-Electric Combination Boiler Fittings Pack (Ei1124500), which provides the ancillary components needed for a code-compliant, complete boiler installation: full-bore service valves (isolation for maintenance), and an automatic bypass valve (ABV) (maintains minimum flow when zone valves close). Sourcing these separately would typically add both cost and procurement time to the job.
Full-bore service valvesAutomatic bypass valve
Technical Specifications
Boiler
Model
BIPROELEC25C — Pro-Electric 25kW Combi Boiler Three Phase
Biasi Combi Fittings Pack Ei1124500: full-bore service valves, ABV
Also Included
Mounting bracket and hardware, installation manual
Warranty and Compliance
Warranty
3 years (register within 45 days at biasi.co.uk)
Warranty Conditions
Part P certificate required; annual service by registered electrician required
Standards
BS EN 12828, BS EN 12831, BS EN 14336, BS 7671 (IEE Wiring Regs 17th Ed.), BS EN 7593
Manufacturer
Biasi UK Ltd, Walsall, UK (est. 1990; parent: Biasi S.p.A., Pordenone, Italy)
Frequently Asked Questions
Does my property need a three-phase supply for this boiler?
Yes. This boiler requires a 400V three-phase 50Hz (3N∼) supply. Standard UK domestic properties are supplied on single-phase 230V and will not be compatible without a three-phase upgrade, which requires DNO (Distribution Network Operator) approval and additional electrical work. Properties that already have three-phase supplies include many commercial premises, rural properties with large electrical demands, and some larger new-builds. Check your electricity meter and supply fuse before ordering. If in doubt, contact your DNO or a qualified electrician.
Can this replace my existing gas combi boiler without changing pipework?
Yes. The Biasi Pro-Electric uses the same connection sizes as a standard gas combi boiler: ¾″ male heating flow and return, ½″ male hot water connections, 15mm PRV. It can connect directly to existing pipework and radiators. The system should be flushed (BS 7593) before connection to remove debris. No flue disconnection/capping is legally required but is recommended for a clean installation.
What is included in the Combi Fittings Pack (Ei1124500)?
The Biasi Pro-Electric Combination Boiler Fittings Pack (Ei1124500) includes full-bore service valves (for isolation during maintenance), and an automatic bypass valve (maintains minimum flow through the boiler when zone valves close, preventing heat build-up). Note that a filling loop is not included and Biasi does not recommend one for this boiler — discuss pressurisation method with your installer.
Why is the energy efficiency rated D for heating but A for hot water?
ErP energy ratings for electric resistance boilers score D for heating because the rating is calculated against a European scale that strongly favours low-temperature heat pumps at the top. An electric boiler that converts electricity to heat at near-100% efficiency scores D because the calculation penalises primary energy conversion (electricity generation losses) rather than the device efficiency itself. The A rating for hot water reflects that the instantaneous hot water production is highly efficient with minimal standby losses. When used with a renewable electricity tariff, the actual carbon footprint is substantially lower than the ErP heating rating implies.
What annual maintenance is required?
The Biasi Pro-Electric warranty requires an annual service by a registered electrician. Service intervals are typically much simpler than gas boilers: there is no burner, flue, heat exchanger, gas valve or ignition system to inspect. A typical annual service covers electrical connections, element resistance checks, flow and pressure settings, and system water quality.
Related Products
Biasi Pro-Electric 14kW Single-Phase Combi Boiler
Smaller single-phase option for 1–2 bed properties
Biasi Pro-Electric 20kW Combi Boiler
Mid-range 3-phase option for 3–4 bed homes
Strom 14.4kW Electric Heat-Only Boiler + 150L Cylinder
Alternative electric heat-only system
EHC Compact All-in-One Electric System Boiler
Alternative electric system boiler range
TypeCombi Boilers
VendorBiasi
SKUBIPROELEC25C
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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