Assess First. Recommend Second.
A cylinder-based system range with 15, 18 and 24 kW heating labels.
CH means central heating; DHW means domestic hot water. Nominal model labels are shown separately from verified ratings. Gas CH maximum/minimum values use the non-condensing basis; a second maximum is shown only where a verified condensing rating is available. The source basis below controls the comparison. No missing value is calculated from another variant.
| Model / fuel | Nominal label (kW) | CH maximum (kW) | DHW output (kW) | CH minimum (kW) | DHW at ΔT 35°C |
|---|---|---|---|---|---|
| Baxi 615 System 2 · Natural gas | 15 | 15 / 16.3 condensing | Stored water / separate design | 4.8 | Not a verified instantaneous flow rating |
| Baxi 615 System 2 · LPG | 15 | 15 / 16.3 condensing | Stored water / separate design | 4.8 | Not a verified instantaneous flow rating |
| Baxi 618 System 2 · Natural gas | 18 | 18 / 19.9 condensing | Stored water / separate design | 4.8 | Not a verified instantaneous flow rating |
| Baxi 618 System 2 · LPG | 18 | 18 / 19.9 condensing | Stored water / separate design | 4.8 | Not a verified instantaneous flow rating |
| Baxi 624 System 2 · Natural gas | 24 | 24 / 26.3 condensing | Stored water / separate design | 4.8 | Not a verified instantaneous flow rating |
| Baxi 624 System 2 · LPG | 24 | 24 / 26.3 condensing | Stored water / separate design | 4.8 | Not a verified instantaneous flow rating |
A built-in system arrangement, stainless steel heat exchanger and brass hydraulics are documented. Easy-Fill 2, an external gauge and Easy-Flue compatibility are listed for this generation.
Consider it when retaining or designing a separate hot-water cylinder. Bathroom demand is addressed by the cylinder, recovery and incoming supply together.
A system boiler may suit a home retaining or adding a separate hot-water cylinder. Assess storage volume, recovery, incoming water supply, controls and cylinder safety together. The boiler has no comparable instantaneous combi DHW flow rating.
Up to 7 years, subject to Baxi terms, product eligibility, registration, commissioning and annual servicing. The eligible installation package is confirmed in your written quotation.
Manufacturer warranty, SwiftHeat installation cover and qualifying Care+ services are separate. Keep the required registration, commissioning and service records. Your quotation confirms the exact terms before purchase.
Manufacturer warranty information · Ongoing servicingExact controller, wiring and generation must be checked against the manufacturer instructions; no universal smart-control compatibility is assumed.
The LPG rows are verified compatible configurations, not separate universal conversion instructions. Fuel conversion and commissioning must follow the exact manufacturer manual.
Discuss heating controlsAssess gas supply, flue route, condensate disposal, heating water quality, controls and future service access. The casing dimensions alone cannot approve a cupboard installation.
A same-arrangement replacement, relocation and conversion involve different work. SwiftHeat confirms the appliance and complete installation scope after survey. Assess First. Recommend Second.
The guide separates nominal model labels from verified heating output. Non-condensing and condensing ratings use different operating conditions. A heat-loss calculation and installation assessment are still required.
Up to 7 years, subject to Baxi terms, product eligibility, registration, commissioning and annual servicing. The eligible installation package is confirmed in your written quotation.
Baxi lists natural gas and LPG configurations for the variants shown here. Manual conversion and commissioning by a suitably competent engineer are required; compatibility does not mean a natural-gas setup can be used unchanged. Confirm the exact generation and instructions.
Checked 1 October 2026. Availability and terms can change; the exact appliance and current instructions are confirmed again at quotation.
Official Baxi product photography and trademarks remain the property of their respective owners. Manufacturer warranty graphics do not confirm the eligibility of a SwiftHeat package.
The installed price for your selected boiler is confirmed after assessment. The quotation covers the appliance, controls, flue, system preparation and any required pipework. A conversion or relocation can have a different scope from a straightforward replacement.
New boiler installations from £1,790 inc. VAT apply to a qualifying standard, straightforward replacement: one bathroom, fewer than 10 radiators and a standard horizontal flue, subject to survey. Specification and warranty selection affect the final cost. This is a general starting offer and is not a price for every model in this catalogue.
Read the starting-package conditions0% options over 3, 6, 9 or 12 months through Humm Group Limited, subject to application, affordability, eligibility, approval and provider terms. Any applicable deposit, fees and repayment conditions are confirmed during your enquiry/application. Acceptance is not guaranteed.
Finance terms and chargesTwo free annual services and a Hive Mini are available on qualifying installations only. Every model is considered under the qualification rules; inclusion in this catalogue does not confirm eligibility. Ask us to confirm the offer in your quotation.
Ask about Care+ eligibilityPlan the maintenance your appliance requires and keep its service records. If you are considering replacement because of a fault, diagnosis can help establish whether repair is a suitable option first.
Boiler servicing · Repair advicePrice confirmed following assessment for this configuration. The general New boiler installations from £1,790 inc. VAT offer does not apply to every model or property.
From or indicative prices remain provisional. SwiftHeat issues a written fixed quotation for the agreed scope after the appropriate property and installation assessment, technical checks and warranty-package verification. Remote information gathering may be suitable initially; a home survey is required where the necessary checks cannot be completed remotely.
We assess heat loss, heating and hot-water requirements, water supply, controls and installation access before recommending an appliance. Bedroom count or a catalogue model number alone cannot establish the right boiler.
Gas Safe registration 978273 · Serving Cardiff, South Wales and across the UK.
Understand suitable boiler types · Start the Boiler Finder · Our installation assessment · Areas we cover
