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If you are searching Viessmann boilers, you are looking at the engineering pick in the UK combi market: a patented Inox-Radial stainless steel heat exchanger across the range, 94% efficiency and 10:1 modulation on the Vitodens 100-W, and built-in WiFi on the models we have reviewed. The catch is the warranty. Two years out of the box, seven free if the install is registered within 30 days, and the 10- and 12-year figures are paid extensions.
This hub covers the current Vitodens range, the warranty structure from Viessmann’s own UK table, typical fitted prices we have already published, who the brand is for, and how it compares with Worcester, Vaillant and Ideal. We have reviewed the Vitodens 100-W (HeatScore 8.7) and the Vitodens 050-W (HeatScore 8.0). For the ranked shortlist across brands, use best combi boiler UK.
Viessmann boilers: brand verdict
The strongest engineering case at mid-market money. Stainless steel Inox-Radial heat exchangers on the 050-W and 100-W, 10:1 modulation and 94% ErP on the 100-W, and WiFi built in on the 100-W rather than sold as an add-on. The concession is the warranty admin: two years unregistered, seven free if someone registers within 30 days, and 10 or 12 years only as a paid extension. Heatable does not fit Viessmann. iHeat does.
HeatScore range across the two Vitodens models we have reviewed. We have not scored the 200-W.
The Viessmann Vitodens range at a glance
| Range | Tier | Warranty (registered) | From (fitted) | HeatScore |
|---|---|---|---|---|
| Vitodens 050-W | Entry | 7 years free; 10 years £180 | £2,000-£2,600 | 8.0 |
| Vitodens 100-W | Mid-premium | 7 years free; 10 years £210; 12 years £270 | ~£2,500 | 8.7 |
| Vitodens 200-W | Premium | 7 years free; 10 years £390; 12 years £480 | not published here | not reviewed |
Warranty figures are from Viessmann UK’s published product-warranty table. Fitted prices are the ranges already used on our 050-W and 100-W reviews and the best combi boiler UK shortlist. The 050-W review puts the 100-W roughly £400 to £600 above the 050-W. We have not reviewed the 200-W, so there is no HeatScore and no fitted-price band of our own.
About Viessmann
Viessmann designs and builds the Vitodens range in Allendorf, Germany. The company started as a family heating business. In 2023 the family agreed to sell Viessmann Climate Solutions, the division that makes the boilers, to the American group Carrier Global for around €12 billion. That deal completed in January 2024. Max Viessmann joined Carrier’s board. The Allendorf headquarters and German production were retained under the deal terms reported at the time.
If you are buying partly on the old family-owned German story, the current position is that the boiler business sits inside a US-listed group, while the factory and the Inox-Radial specification have not changed. That is the version we use on the Vitodens 100-W review.
In the UK the brand sits as the engineering alternative to Worcester and Vaillant. It does not have Worcester’s service-network density or homeowner recognition. It does put a patented stainless steel heat exchanger into the entry 050-W, which most rivals at that price do not. Which? has awarded Best Buy status to both models we have reviewed; award lists are reviewed periodically, so check the current listing if that is central to your decision.
One practical constraint: iHeat carries Viessmann. Heatable does not. If you have already shortlisted a Vitodens, start the quote at iHeat. If you want a second number on Worcester, Vaillant, Ideal or Baxi, use Heatable. The head-to-head is on Heatable vs iHeat.
The Viessmann range explained
Vitodens 050-W (entry)
The cheapest way to get Viessmann’s Inox-Radial stainless steel heat exchanger. Combis in 25kW, 30kW and 35kW. ErP efficiency is 92% (A rated), not the “up to 97%” figure you will see on some sales pages. Modulation is 8:1. Size is 700 × 400 × 300mm, so it fits a standard kitchen cupboard. Natural gas or LPG with no conversion kit. Hydrogen blend ready to 20%.
Warranty: two years out of the box, seven free if registered within 30 days, ten years as a £180 paid extension. The heat exchanger is covered separately for ten years. A like-for-like combi swap typically lands between £2,000 and £2,600 fitted, with the 25 at the bottom and the 35 at the top. The boiler alone runs roughly £930 to £1,150. Full write-up: Vitodens 050-W review (HeatScore 8.0).
Vitodens 100-W (mid-premium)
The model we rank as best engineering on the best combi boiler UK list. Combi, system and heat-only. Combi hot-water outputs of 27.3kW, 31.7kW and 34.9kW (sold as the 26, 30 and 35). Flow rates 10.6 to 14.3 L/min, with 12.3 L/min on the volume-selling 30. ErP efficiency 94%. Modulation 10:1. Built-in WiFi and the ViCare app on combi and system models. Made in Allendorf. Around 35kg. 700 × 400 × 300-360mm depending on output.
Warranty: two years out of the box, seven free on registration within 30 days, then £210 for ten years and £270 for twelve, registered by the installer on Viessmann’s VPlus platform. The 050-W review puts the step up at roughly £400 to £600 more fitted. The shortlist figure we use for the 100-W is from about £2,500 fitted. Full write-up: Vitodens 100-W review (HeatScore 8.7).
Vitodens 200-W (premium, not reviewed)
Viessmann’s current premium wall-hung condensing boiler, listed on the official UK gas-boiler page with rated output from 1.9 to 35kW, Lambda Pro Plus combustion control and a colour touchscreen. The same page says “10 years standard warranty”. Viessmann’s warranty table for the 200 still shows two years out of the box, seven free via the homeowner portal, then £390 for ten years and £480 for twelve. Those two official pages disagree on what “standard” means, so treat the table as the terms and ask your installer which figure is in the quote. We have not reviewed the 200-W and we have not published a HeatScore or a fitted-price band for it.
The official lineup also includes the floor-standing Vitodens 222-F (with a 100-litre cylinder) and a 100-W heat-only variant at 11, 16, 19, 25 and 32kW. Those sit outside the two reviews this hub draws on.
Viessmann warranties explained
This is the part of buying a Viessmann that catches people out. Viessmann’s own UK warranty page is clear: to get longer than the two-year term in the standard Terms and Conditions of Sale, the installation must be registered within 30 days. You or your installer can do that. Paid extensions on some models have to be registered by the installer on the VPlus platform.
| Range | Out of the box | Registered in 30 days | Paid extension |
|---|---|---|---|
| Vitodens 050-W | 2 years | 7 years, free | 10 years, £180 |
| Vitodens 100-W | 2 years | 7 years, free | 10 years £210; 12 years £270 |
| Vitodens 200-W | 2 years | 7 years, free | 10 years £390; 12 years £480 |
Source: Viessmann UK product-warranty table. Annual Gas Safe servicing is required throughout or cover lapses. The Inox-Radial heat exchanger is covered under a separate heat-exchanger guarantee, which our model reviews describe as ten years.
Seven years free is a competitive term once someone has done the registration. Two years is not, and it is what you get if the 30-day window is missed. iHeat registers the warranty as part of the fixed-price job. If you use a local engineer, ask for the registration confirmation in writing, and check whether any paid extension is in the price or is the extra you would be buying yourself.
If you want a long warranty with no registration deadline and no accreditation hoop, Alpha gives ten years as standard on the E-Tec Plus, rising to 13 with the Premier Pack Plus. That is the cleaner paperwork, not the stronger engineering.
Viessmann boiler prices
Indicative fitted prices we have already published, for like-for-like swaps. Conversions and awkward installs cost more. Prices run lower in the north and higher in London and the South East.
| Model | What we have published |
|---|---|
| Vitodens 050-W (25 / 30 / 35) | £2,000-£2,600 fitted. Boiler alone roughly £930-£1,150. |
| Vitodens 100-W | From about £2,500 fitted on our shortlist. The 050-W review puts it £400-£600 above the 050-W. |
| Vitodens 200-W | No fitted-price band published on HomeBoiler yet. |
Those figures assume the boiler, Gas Safe installation, flue, flush, filter, controls, warranty registration and old-boiler removal when you order through iHeat. Your live quote is the one that counts. For how we pick the installer, see best boiler installers UK.
Viessmann through iHeat. Other brands through Heatable.
iHeat is the online installer that actually lists Viessmann. Heatable is the one we send most other homes to first, for 48-month 0% and a broader credit panel.
- Carries Viessmann, Alpha and Glow-worm
- Quote in about 60 seconds
- Next working day if you order by 3pm
- Which? Trusted Trader
- Worcester, Vaillant, Ideal, Baxi, Navien
- Does not list Viessmann
- 0% on selected boilers, 12 to 48 months
- Which? Trusted Trader
Viessmann vs Worcester vs Vaillant vs Ideal
| Viessmann | Worcester Bosch | Vaillant | Ideal | |
|---|---|---|---|---|
| Manufacturing | Allendorf, Germany | Gas boilers made in Worcester | Germany | Hull, Yorkshire |
| Heat exchanger | Stainless Inox-Radial | Mixed: stainless on 1000 and 8000, aluminium on 2000 and 4000 | Stainless steel | Aluminium |
| Top-tier modulation | 10:1 (100-W) | See model reviews; 4000 is 10:1 on the shortlist, 8:1 on the 100-W comparison table | 12:1 (ecoTEC Plus) | 6:1 (Logic Max, Vogue MAX) |
| Warranty route | 2 years, then 7 free if registered in 30 days | Accredited installer plus filter; 1000 and 2000 cannot be extended | Longer standard terms; ecoTEC Plus reaches 12 on our Vaillant hub | Accredited installer for the longest Vogue MAX term |
| Built-in WiFi | Yes on the 100-W combi and system | Optional | Optional | Halo add-on |
| UK service network | Smaller | Densest in the UK | Strong | Strong |
| Online installer | iHeat | Heatable and iHeat | Heatable and iHeat | Heatable and iHeat |
Worcester Greenstar 4000 modulation is listed as 10:1 on the best-combi shortlist and as 8:1 on the Vitodens 100-W comparison table. We have left both figures in view rather than picking one.
The read across those four: Viessmann wins on the heat exchanger at every price we have reviewed, and on built-in WiFi at the 100-W. Worcester wins on the service network and the badge. Vaillant wins on modulation depth and a simpler long-warranty path on the ecoTEC Plus. Ideal wins on UK manufacturing and price per pound. For the model-level comparisons, use the Worcester Bosch and Vaillant hubs.
Are Viessmann boilers any good?
Yes, if you will register the install. The 100-W is the second-highest HeatScore we have published on a current combi (8.7), level with the Vaillant ecoTEC Plus and behind the Worcester Greenstar 8000 at 8.9. The 050-W scores 8.0. Both use the same patented stainless steel exchanger, which is the component that usually decides whether a boiler reaches the mid-teens or dies around year ten.
Our 100-W review puts expected life, with annual Gas Safe servicing, in excess of 15 years, at the upper end for a UK combi. That is a design claim plus the exchanger argument, not a promise. Annual servicing is also a condition of the warranty.
The concessions are the smaller UK engineer network versus Worcester, lower homeowner recognition at resale, and a warranty that is only competitive after a piece of admin. Miss the 30-day window and you have bought premium engineering with two years of cover.
Viessmann customer service
Viessmann’s UK support, warranty claims and engineer dispatch run from the UK. We have not published the phone number here in case it changes; the current number is on Viessmann’s own site. The network is smaller than Worcester’s. Rural Scotland and Wales can wait longer for a warranty visit, which is the same pattern we note on Vaillant.
For installation issues, your installer is the first call. For a Vitodens that is iHeat. For warranty repairs once the boiler is registered and serviced, Viessmann handles the claim. The 100-W display names the failed component rather than a generic code, and Viessmann support can see some faults remotely through ViCare.
ViCare and smart thermostats
The 100-W combi and system models have WiFi built in and connect to the ViCare app for scheduling, weather compensation and remote diagnostics. The heat-only 100-W needs a separate module. Some 050-W variants also need the Vitoconnect module, so check what the quote includes.
Third-party thermostats: the 100-W review lists tado°, Hive and Nest. The 050-W review is stricter on Hive. Hive is not OpenTherm compliant, so pairing it with a 050-W throws away the modulation range. On the 050-W, use tado° or ViCare. We have left that model-level difference in place rather than flattening it into one brand rule.
Pros and cons of choosing Viessmann
Where Viessmann wins
- Patented Inox-Radial stainless steel heat exchanger on the 050-W and 100-W, where Ideal and the mid Worcester range use aluminium
- Separate heat-exchanger guarantee, described as ten years on our model reviews
- 94% ErP and 10:1 modulation on the 100-W
- Built-in WiFi on the 100-W combi and system
- Which? Best Buy on both models we have reviewed
- 050-W fits a standard cupboard at 700 × 400 × 300mm
- Hydrogen blend ready to 20% on the reviewed models
Where Viessmann loses
- Two years of cover if the install is not registered within 30 days
- 10- and 12-year terms are paid extensions (£180 to £480 depending on range)
- Smaller UK service network than Worcester
- Modulation trails the Vaillant ecoTEC Plus at 12:1
- Lower brand recognition with UK homeowners
- Heatable does not fit the brand, so you have one fewer online quote path
- Boiler business is Carrier-owned, not family-owned
Should you buy a Viessmann boiler in 2026?
Buy one if you plan to stay long enough for the heat exchanger to matter (roughly eight years or more), you will register the boiler within 30 days or use an installer who does, and you want stainless steel without paying flagship Worcester money. Quote iHeat first.
- 3-bed semi, one bathroom, staying 8+ years: Vitodens 100-W 30. 12.3 L/min, 94% ErP, 10:1 modulation, built-in WiFi. HeatScore 8.7.
- Same home, tighter budget: Vitodens 050-W 30. Same stainless exchanger, 92% ErP, 8:1 modulation, seven years free if registered. HeatScore 8.0.
- Two bathrooms in regular use: 100-W 35 at 14.3 L/min, or the 100-W system boiler with an unvented cylinder if two showers run at once.
- Flat or small terrace: 050-W 25. Compact, quiet, stainless at entry money.
- Look elsewhere if: you want the largest UK service network (Worcester), a long warranty with no 30-day window (Vaillant ecoTEC Plus, or Alpha E-Tec Plus), or UK manufacturing at a lower price (Ideal or Baxi).
For the installer decision on a Vitodens, iHeat is the path. For how that sits against Heatable on finance and credit, use Heatable vs iHeat.
Frequently asked questions about Viessmann boilers
Yes, with the registration done. The Vitodens 100-W scores 8.7 on our HeatScore, the 050-W scores 8.0, and both use a patented stainless steel heat exchanger. Which? has given both a Best Buy. The weak point is the warranty if nobody registers the install within 30 days.
Two years out of the box on the 050-W, 100-W and 200-W. Register within 30 days and that becomes seven years free. Paid extensions then run to 10 years (£180 on the 050-W, £210 on the 100-W, £390 on the 200-W) and 12 years on the 100-W (£270) and 200-W (£480). Annual Gas Safe servicing is required. Figures are from Viessmann UK’s own table.
Our 100-W review says they are designed to last in excess of 15 years with annual servicing, at the upper end for a UK combi. The stainless Inox-Radial exchanger is the main reason. Servicing is also what keeps the warranty valid.
On the heat exchanger and on 100-W modulation, Viessmann is the stronger engineering buy against a Greenstar 4000. Worcester wins on the size of the UK service network, brand recognition, and a warranty that does not hinge on a 30-day registration window. For long ownership pick the Viessmann; for nationwide support pick the Worcester. See the Worcester Bosch hub.
Carrier Global. The family sold Viessmann Climate Solutions in a deal that completed in January 2024. Production stays in Allendorf. The boilers are still designed and built there.
No. Heatable’s list is Worcester, Vaillant, Ideal, Baxi and Navien. iHeat is the online installer that carries Viessmann, plus Alpha and Glow-worm. Quote iHeat for a Vitodens. Quote Heatable if you switch to a brand it does fit.
For most homes the Vitodens 100-W, HeatScore 8.7. Take the 050-W if the extra £400 to £600 does not fit the budget: you keep the stainless exchanger and lose some efficiency, modulation, built-in WiFi and the 12-year paid ceiling.
This guide was last updated in August 2026. HeatScore ratings reflect our independent reviews of the Vitodens 050-W and 100-W. Warranty terms are taken from Viessmann UK’s published table and can change, so confirm the details on your quote. We are not a credit broker, lender or installer. iHeat and Heatable handle quoting, finance and installation directly.