Assess First. Recommend Second.
A cylinder-based gas system boiler with four heating-output choices, rather than an instantaneous combi.
Subject to registration, correct commissioning and recorded annual servicing.
Your written quotation confirms the cover included. Register within one month of installation.
The model-specific UK page advertises 10 years of boiler warranty. The installation manual requires registration within one month, correct installation and commissioning, a completed Benchmark checklist and servicing at least annually by a competent Gas Safe registered engineer, with records retained. System-water treatment and any required protection components must meet the selected manual. Maximum cover is not automatic; the written quotation confirms actual cover. No manufacturer accreditation or paid extension entitlement is assumed. Any proposed extension, qualifying components or installer eligibility must be verified before agreement. Component-only cover must not be presented as whole-boiler cover.
Official model warranty information · Check registered warranty · Installation and servicing requirementsA cylinder-based gas system boiler with four heating-output choices, rather than an instantaneous combi.
Natural-gas specification table: heating at 80/60°C; condensing heating at 50/30°C. LPG conversion is supported but no LPG performance figure is inferred.
| Model / configuration | Heating at 80/60°C | Heating at 50/30°C | Hot-water output | Hot-water delivery |
|---|---|---|---|---|
| NCB500-15K System | 2.6–15 kW | 16.4 kW | Separate cylinder | No instantaneous rating |
| NCB500-18K System | 3.1–18 kW | 19.4 kW | Separate cylinder | No instantaneous rating |
| NCB500-24K System | 4.2–24 kW | 25.6 kW | Separate cylinder | No instantaneous rating |
| NCB500-30K System | 4.5–30 kW | 32.6 kW | Separate cylinder | No instantaneous rating |
Navien documents natural-gas/LPG conversion for these configurations using the supplied kit. A Gas Safe engineer qualified for LPG must verify the correct kit, gas supply and manual, then convert, label and commission the appliance. The displayed output, flow and efficiency figures are natural-gas data, not verified LPG performance.
Model designations are verified; a separate merchant SKU or retail order code has not been verified and must be confirmed before ordering.
| Configuration | Weight | Published modulation | Energy rating |
|---|---|---|---|
| NCB500-15K System | Confirm from model manual | 6:1 — manufacturer table | ErP A (93%) |
| NCB500-18K System | Confirm from model manual | 6:1 — manufacturer table | ErP A (93%) |
| NCB500-24K System | Confirm from model manual | 6:1 — manufacturer table | ErP A (93%) |
| NCB500-30K System | Confirm from model manual | 7:1 — manufacturer table | ErP A (93%) |
A+ is a conditional package rating with the specified Navien Smart Plus controls, not the appliance alone. Lift weight and shipping weight can differ. The product page lists three weight figures for four configurations; individual mapping needs confirmation from the model manual.
Outlet descriptions are manufacturer guidance, subject to sufficient measured water flow and dynamic pressure, outlet temperatures and pipework. Bathroom count alone does not establish delivery or suitability.
The 15, 18, 24 and 30 models provide different heating ranges in a compact casing. Smart Plus and Multikit compatibility are documented, subject to the selected installation design.
Specify the boiler alongside cylinder capacity, recovery and safety controls. A system-boiler heating rating is not a tap-flow rating.
The model-specific UK page advertises 10 years of boiler warranty. The installation manual requires registration within one month, correct installation and commissioning, a completed Benchmark checklist and servicing at least annually by a competent Gas Safe registered engineer, with records retained. System-water treatment and any required protection components must meet the selected manual. Maximum cover is not automatic; the written quotation confirms actual cover. No manufacturer accreditation or paid extension entitlement is assumed. Any proposed extension, qualifying components or installer eligibility must be verified before agreement. Component-only cover must not be presented as whole-boiler cover.
Official model warranty statement · Registered warranty lookupSmart Plus control-pack, three-zone and Navien Multikit compatibility are listed. Confirm the cylinder, sensors, valves and control strategy against the selected manual.
Casing: 680 × 395 × 283 mm (H × W × D). Pipework, flue and installation/service clearances are additional.
The Finder can shortlist individual configurations from your fuel and design answers. LPG conversion compatibility is recorded, but LPG-specific performance and supply must be confirmed at survey. Final output is subject to heat-loss, water and installation assessment.
System guidanceSpecify the boiler alongside cylinder capacity, recovery and safety controls. A system-boiler heating rating is not a tap-flow rating.
The model-specific UK page advertises 10 years of boiler warranty. The installation manual requires registration within one month, correct installation and commissioning, a completed Benchmark checklist and servicing at least annually by a competent Gas Safe registered engineer, with records retained. System-water treatment and any required protection components must meet the selected manual. Maximum cover is not automatic; the written quotation confirms actual cover. No manufacturer accreditation or paid extension entitlement is assumed. Any proposed extension, qualifying components or installer eligibility must be verified before agreement. Component-only cover must not be presented as whole-boiler cover.
Navien lists natural-gas and LPG support with an included conversion kit. Conversion, gas supply and commissioning must be completed by a suitably qualified engineer. The natural-gas figures in this guide are not assumed LPG ratings.
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 adviceProduct photography and technical information: Navien UK. Checked 2 October 2026. Family casing views may be shared across outputs; current stock and the precise supplied model are confirmed before quotation.
Price 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.
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