Viessmann Vitodens 100-W System Boiler Cost with Installation
The Viessmann Vitodens 100-W System costs approximately £1,350 for the 19kW, £1,450 for the 26kW, £1,650 for the 30kW, and £1,650 for the 35kW.
With installation costs of around £1,500, the total cost of the boiler and installation can cost anywhere between £2,600 and £2,880.
The Vitodens 100-W is Viessmann’s flagship residential boiler and the most widely installed Viessmann model in the UK.
In system configuration, it brings the same stainless steel Inox-Radial heat exchanger, MatriX-Plus burner, built-in WiFi, and 1:6 modulation that make the 100-W combi so well regarded – configured to charge a hot water cylinder rather than deliver hot water on demand. Four outputs from 19kW to 35kW, 94% efficiency, and a 10-year warranty with a Viessmann Academy Trained Installer.
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See more of the Viessmann Vitodens 100-W system boiler specifications below:
| Viessmann Vitodens 100-W System Boiler Product Table | |||||
 | Models | 19kW | 26kW | 30kW | 35kW |
 | Type | System | System | System | System |
| Fuel | Gas | Gas | Gas | Gas | |
| Condensing | Yes | Yes | Yes | Yes | |
| Efficiency rating (%) | 94 | 94 | 94 | 94 | |
| ErP | A | A | A | A | |
| LPG compatible | No | No | No | No | |
| Standard guarantee | 5 years | ||||
| Max guarantee | 10 years* | ||||
| Max output (kW) | 19 | 26 | 30 | 35 | |
| Modulation ratio | 1:6 | ||||
| Heat exchanger | Stainless steel (Inox-Radial) | ||||
| DHW flow rate | Determined by cylinder | ||||
| Mounting | Wall-mounted | ||||
| Dimensions (mm) | 700 x 400 x 350 | ||||
| Built-in WiFi | Yes | ||||
| Typical price (incl. flue) | £1,350 | £1,450 | £1,550 | £1,650 | |
| Typical installation cost (incl. VAT) | £1,500 | ||||
| Total cost | £2,850 | £2,950 | £3,050 | £3,150 | |
*10-year warranty with Viessmann Academy Trained Installer and annual servicing. Terms and conditions apply.
Viessmann Vitodens 100-W System Boiler overview
The Vitodens 100-W is where Viessmann’s reputation is built and sustained. It’s their best-selling model, it holds a Which? Best Buy award, and it’s the boiler that converted a generation of UK installers who’d previously stuck to domestic brands. In system configuration, it pairs with a hot water cylinder to supply large volumes of stored hot water simultaneously to multiple bathrooms – the configuration that outperforms any combi when peak demand is genuinely high.
The step up from the 050-W System is substantial. The 050-W uses an aluminium heat exchanger; the 100-W uses the stainless steel Inox-Radial. The 050-W tops out at 25kW; the 100-W goes to 35kW. The 050-W carries a 3-year standard warranty; the 100-W carries 5 years standard with a route to 10 via a Viessmann Academy Trained Installer. If you’re choosing between the two, the 100-W is the right answer for any property with higher output requirements, harder water, or a longer ownership horizon.
| Viessmann Vitodens 100-W System Boiler Range | |||
| Model | Suitable for | Radiators | Notes |
| 19kW | Small to medium homes, 2-3 bedrooms | Up to 12 | Pairs well with a 150-litre cylinder |
| 26kW | Medium homes, 3 bedrooms | Up to 16 | Good all-round choice for family homes |
| 30kW | Medium-large homes, 3-4 bedrooms | Up to 20 | Most popular system output |
| 35kW | Large homes, 4+ bedrooms | Up to 20+ | For properties with high heat demand |
Key benefits at a glance
- ErP A-rated efficiency (94% efficient)
- Stainless steel Inox-Radial heat exchanger – Viessmann’s signature component
- MatriX-Plus burner for low-noise, low-emission operation
- Built-in WiFi with ViCare app as standard
- 1:6 modulation ratio for efficient low-demand operation
- Four outputs from 19kW to 35kW
- Which? Best Buy award holder
- Pre-plumbing jig included for faster installation
- Flue lengths up to 19m
- 5-year standard warranty, 10 years with Viessmann Academy Trained Installer
- Made in Germany
- Hydrogen blend ready (up to 20%)
Viessmann Vitodens 100-W System Boiler technical specifications
The 100-W’s reputation rests on two components: the stainless steel Inox-Radial heat exchanger and the MatriX-Plus burner. Both are Viessmann proprietary designs, both are manufactured in Germany, and together they account for the boiler’s efficiency, quiet operation, and long service life. At 94% ErP efficiency with a 1:6 modulation ratio, the 100-W System performs consistently well across the full range of UK heating demand conditions – from the steady low-load requirement of a well-insulated modern home to the high-demand peaks of a large family property in a cold snap.
Output and efficiency ratings
All four outputs run at 94% ErP A-rated efficiency. As condensing boilers, they recover heat from exhaust gases that older non-condensing boilers vented outside. The seasonal efficiency improvement over a pre-2005 installation is typically meaningful and visible in bills within the first heating season.
The 1:6 modulation ratio means the 35kW model can operate as low as approximately 5.8kW under minimal demand. For a well-insulated home that only needs a light top-up on a mild day, the boiler holds that temperature steadily without cycling on and off – reducing wear on components and maintaining more even room temperatures than boilers with narrower modulation ranges.
Dimensions
At 700mm tall, 400mm wide, and 350mm deep, the 100-W System is deeper than the 050-W System (300mm) and the Ideal Logic Max (278mm), but fits the majority of standard boiler positions. The pre-plumbing jig is included, allowing pipework to be prepared in advance so the boiler drops onto prepared connections on installation day – a time-saver that experienced Viessmann installers use routinely. Flue runs of up to 19m are supported across all four outputs.
What’s under the casing
The Inox-Radial stainless steel heat exchanger is the component that justifies the 100-W’s premium over aluminium-exchanged rivals. Stainless steel resists limescale build-up in hard water areas and handles the repeated thermal cycling of daily use better over a long service life. The Inox-Radial design distributes heat exchange across a radial surface rather than a flat one, increasing the effective surface area and improving efficiency at the same casing volume. The same exchanger design has accumulated millions of installations across the Viessmann range in over 70 countries.
The MatriX-Plus burner fires in a cylindrical matrix pattern rather than a flat flame, which achieves more even combustion across the burner surface and reduces thermal stress on the heat exchanger. It’s one of the reasons the 100-W is consistently among the quietest system boilers in independent tests.
Built-in WiFi connects to the ViCare app as standard – no separate hub or gateway required. Remote temperature control, schedule programming, and system diagnostics are all accessible from a smartphone. The boiler is also OpenTherm compatible with tado, Nest, and Honeywell for full weather and load compensation.
Prices and installation costs
The Viessmann Vitodens 100-W System costs approximately approximately £1,350 for the 19kW, £1,450 for the 26kW, £1,650 for the 30kW, and £1,650 for the 35kW – all including a standard horizontal side-wall flue. The cylinder and Viessmann filter are separate purchases. If a vertical roof flue is required, budget an additional £300-£500.
Using a mid-range installation figure of £1,500:
| Viessmann Vitodens 100-W System Boiler Costs | ||
| Output size | Unit cost (incl. flue) | Total (incl. installation) |
| 19kW | £1,350 | £2,850 |
| 26kW | £1,450 | £2,950 |
| 30kW | £1,550 | £3,050 |
| 35kW | £1,650 | £3,150 |
These prices assume a like-for-like system boiler replacement with an existing cylinder in place. A new unvented cylinder adds £500-£1,000 plus fitting. Converting from a combi with no existing cylinder can add up to £2,000 to the total project cost.
These prices are indicative, based on our research and actual boiler prices submitted to WhatPrice by homeowners. For a broader overview of Viessmann pricing, see our Viessmann boiler prices guide. Get quotes from at least three Gas Safe registered installers, or use the WhatPrice Boiler Cost Calculator for a guide price.
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Warranty and support
Five years standard, ten years with a Viessmann Academy Trained Installer and annual servicing by a Gas Safe engineer. Registration must be completed within 30 days of installation. The 5-year standard baseline is shorter than the Ideal Logic Max (10 years standard) and the Baxi 800 System (10 years standard) – the route to 10 years requires an Academy Trained Installer, which is worth confirming before booking.
Viessmann’s engineer and parts network has strengthened considerably in the UK over the past decade. Earlier criticism about parts availability has largely dated – Viessmann’s UK growth has been accompanied by significant investment in the installer network and parts infrastructure.
Installation information
A like-for-like system boiler replacement is a one-day job. The included pre-plumbing jig means pipework can be prepared in advance, so the boiler drops onto prepared connections and commissioning begins without delay. Experienced Viessmann Academy installers know the 100-W well enough to complete the job efficiently. If fitting a new cylinder at the same time, expect one to two days – and confirm G3 qualification alongside Gas Safe registration.
What to expect on installation day
- Survey first. Boiler position, flue route, condensate pipe path, and cylinder compatibility confirmed. The pre-plumbing jig is confirmed at this stage if being used.
- Out with the old. Drained, disconnected, and removed. Switching from a combi means cylinder pipework is run at this stage.
- In with the new. Drops onto prepared connections if the pre-plumbing jig was used. Flue connected. Magnetic filter fitted separately – confirm this is in the quote.
- ViCare setup. Built-in WiFi configured and app connected. OpenTherm thermostats paired and tested.
- Handover. Benchmark logbook completed. Warranty registered within 30 days. Confirm Academy installer status and registration before the engineer leaves.
Do you need a system flush or filter?
The Vitodens 100-W’s stainless steel Inox-Radial heat exchanger performs best in a clean system – fitting a quality magnetic filter from day one is the single most effective thing you can do to protect it long-term.
A Viessmann Vitoset or compatible Adey filter satisfies the UK Building Regulations requirement for a magnetic filter on any new installation and is typically a condition of the extended warranty.
Budget £80-£150 and confirm it’s in the quote before the job starts, not after.
On systems over ten years old, a powerflush before the new boiler goes in is worth the £350-£800 cost – iron oxide sludge in the pipework will find the heat exchanger eventually.
Finding a Gas Safe registered engineer
All gas boiler installations must be carried out by a Gas Safe registered engineer. For the 10-year warranty, Viessmann Academy Trained status is additionally required. For a new unvented cylinder, G3 qualification is also needed.
How the Viessmann Vitodens 100-W System Boiler compares
| Viessmann Vitodens 100-W System Boiler Comparison Table | |||
| Model | Viessmann Vitodens 100-W System | Viessmann Vitodens 050-W System | Worcester Bosch Greenstar 8000+ System |
| Typical unit price (30kW) | £1,550 | £1,150 | £1,400 |
| Heat exchanger | Stainless steel (Inox-Radial) | Aluminium | Aluminium |
| Standard warranty | 5 years | 3 years | 5 years |
| Max warranty | 10 years | 10 years | 12 years |
| Built-in WiFi | Yes | Yes | Yes |
| App control | ViCare (built-in) | ViCare (built-in) | EasyControl (built-in) |
| Modulation | 1:6 | 1:6 | Not specified |
| Max system output | 35kW | 25kW | 35kW |
| LPG compatible | No | No | Yes |
For personalised guidance on choosing the right boiler, we recommend speaking with a Gas Safe registered engineer.
Final thoughts – is the Viessmann Vitodens 100-W System right for you?
The 100-W System is the right boiler for homeowners who want German engineering, a stainless steel heat exchanger, and built-in WiFi without paying the premium of a Worcester Bosch 8000+. At £1,550 for the 30kW, it sits above the 050-W System and the 8000+, but brings the most technically distinctive component in the comparison – the Inox-Radial stainless steel heat exchanger – at the middle price point.
The warranty structure is the main practical consideration. Five years standard is shorter than the Ideal Logic Max and Baxi 800 System, both of which offer 10 years as standard without installer conditions. The 10-year Viessmann tier requires an Academy Trained Installer, which is not difficult to find in most UK regions but is a step that needs to be confirmed before booking rather than assumed. For homeowners who can verify Academy status at the quoting stage, the 10-year cover is competitive with anything in the class.
Against the 050-W System, the 100-W’s stainless steel heat exchanger, higher output ceiling (35kW vs 25kW), and stronger standard warranty (5 years vs 3) are the meaningful upgrades. The extra £130 at 30kW for those three improvements is well spent in most cases, particularly in hard water areas where the heat exchanger material matters most over a 10-15 year ownership period.
FAQ
Is the Vitodens 100-W System hydrogen-ready?
Yes. The boiler is certified for use with up to a 20% hydrogen blend in the gas supply.
Is the Vitodens 100-W System LPG compatible?
No. The 100-W System is natural gas only. For LPG properties, consider the Viessmann ecoTEC plus range, which offers LPG compatibility.
Does the Vitodens 100-W System include built-in WiFi?
Yes. All four outputs include built-in WiFi connecting to the Viessmann ViCare app as standard – no separate hub required. Remote temperature control, schedule programming, and system diagnostics are available from a smartphone. The boiler is also OpenTherm compatible with tado, Nest, and Honeywell.
What is the warranty on the Viessmann Vitodens 100-W System?
5 years standard. This extends to 10 years when installed by a Viessmann Academy Trained Installer and registered within 30 days of installation, with annual servicing by a Gas Safe engineer required to maintain cover.
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