Assess First. Recommend Second.
An internal oil combi with its own hot-water provision, for a surveyed off-gas installation rather than the gas replacement starting package.
Model names identify discrete variants. The heating and hot-water columns reproduce the stated output basis from the cited manufacturer documentation; they are not interchangeable. Where a model label differs from rated output, compare the rating rather than rounding it to the name. An oil model band describes that appliance’s settings, not every integer as a separate model to buy.
| Exact model / fuel variant | Fuel | Heating output (kW) | DHW output (kW) |
|---|---|---|---|
| Greenstar Heatslave II 12/18 2022+ · Part 7 731 600 260 | Oil | 18 Maximum of the documented 12–18 kW boiler band | 18 |
| Greenstar Heatslave II 18/25 2022+ · Part 7 731 600 261 | Oil | 25 Maximum of the documented 18–25 kW boiler band; manufacturer installation manual 6721843978, sections 3.2–3.3, does not publish a separate maximum DHW kW rating | Not independently verified |
| Greenstar Heatslave II 25/32 2022+ · Part 7 731 600 262 | Oil | 32 Maximum of the documented 25–32 kW boiler band; manufacturer installation manual 6721843978, sections 3.2–3.3, does not publish a separate maximum DHW kW rating | Not independently verified |
Manufacturer installation manual 6721843978 (2022/01), sections 3.2–3.3, confirms the 18/25 and 25/32 internal variants and their rated heating outputs. DHW is specified by maximum draw-off flow and temperature rise; a separate maximum DHW kW rating is not published in these tables and remains unavailable. No DHW kW figure is inferred from heating output, draw-off flow or an external model.
Unless an operating temperature is expressly stated, the current product-page output label does not specify its measurement temperature. The exact installation literature must be checked before technical design; no modulation range or seasonal performance claim is inferred here.
The internal utility format combines space heating and hot water without a separate household cylinder. Front access and the position of the worktop deserve attention when planning servicing.
An internal oil combi with its own hot-water provision, for a surveyed off-gas installation rather than the gas replacement starting package.
A combi supplies heating and hot water within the appliance arrangement and normally avoids a separate household hot-water cylinder. Check the measured incoming mains pressure and flow, the taps and showers used together, and the distances to outlets. Increasing the appliance rating cannot create a water supply the home does not receive. Oil combis have a different internal hot-water arrangement from gas combis; do not compare the printed numbers as interchangeable flow performance.
For an oil installation, assess the tank, fuel delivery route, oil-line condition, flue, condensate disposal and safe access. Confirm the precise appliance fuel specification from its instructions. Alternative fuels or conversion kits are separate engineering decisions; the catalogue does not authorise use of an unverified fuel. Outdoor pipework needs an assessed protection strategy. SwiftHeat confirms whether it can provide the required installation and servicing scope before accepting the work.
A like-for-like arrangement and a conversion have different scopes. Check pipework condition, system cleaning and protection, controls, siting and future access before comparing quotations. Removing a cylinder, relocating the boiler or changing fuel can affect the whole project. Bedroom count, bathroom count and the model designation cannot replace a heat-loss calculation and a water-supply assessment.
Manufacturer standard cover: 2 years. With the qualifying system filter: 5 years. Maximum eligible extended cover: 7 years, conditional on a Greenstar System Filter and the qualifying installer loyalty/accreditation arrangement in the manufacturer terms. A System Filter Micro does not qualify for this longer extension. SwiftHeat’s installer status and your package must be confirmed in writing; the maximum is not automatically included.
The manufacturer guarantee and SwiftHeat service offers are separate. Your written quotation must identify the exact cover and eligible accessories. Keep installation and commissioning records, complete manufacturer registration in the required time and arrange the annual servicing required by the applicable terms. The installer must establish eligibility before promising extended cover.
Current guarantee schedule · Manufacturer guarantee terms · Arrange ongoing servicingVerified 1 October 2026. Product availability and manufacturer terms can change; the final specification is checked again at quotation.
Exact manufacturer product information · Verified technical source 1 · Verified technical source 2 · Official manuals and technical literatureThe 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
