PHAM NEWS | OCTOBER 2026 24 Gas & Oil Boilers


Simplifying boiler installation without compromise


The Vitodens 025-W is designed to challenge established perceptions of Viessmann boilers while addressing a gap in the UK heating market. Lauren Mason explains how combining a compact format with pre-commissioning and simplified installation makes this combi especially suitable for housing projects.


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here has long been a belief among some installers that, while Viessmann boilers are well engineered


and reliable, they can be more technically demanding and time-consuming to install than competing products. For high- volume housing projects, where engineers may be expected to complete multiple installations in a day, that can be a significant consideration. However, Viessmann is now


challenging that perception with the Vitodens 025-W, a compact gas condensing combi boiler designed specifically for the large-scale specification market. Available in 24 and 28kW outputs, it’s been developed with direct input from the trade about what limits productivity on site. The result is a unit designed


to make installation and commissioning as quick and uncomplicated as possible, without compromising engineering quality, performance or durability. This fulfils a long-standing UK market need for a premium- quality, quick-fitting, compact combi at a price that works for both the installer and the end user.


Against the clock This focus on productivity reflects the pressures facing installers across the housing sector. Whether replacing boilers in rental properties, refurbishing social housing or fitting out new homes at scale, engineers are working in an environment where labour costs, tight programmes and the need to minimise disruption all place a premium on time. Simplifying commissioning is therefore not simply a convenience for the installer; it can directly influence the economics and viability of an entire project. The pre-commissioned


Lauren Mason Residential gas product manager at Viessmann


design of the Vitodens 025-W addresses this directly. Rather than requiring engineers to work through a lengthy commissioning procedure, the boiler is supplied ready for installation. The engineer is required only to complete a five- minute flue gas sensor check via the white LED screen on the deliberately minimal control panel. This ‘one and done’ approach


is a direct implementation of the feedback we received from installers. It represents a very significant departure from the commissioning process associated with earlier generations of Viessmann boilers which could involve up to 15 steps. The sister product to the


This ‘one and done’ approach is a very significant


departure from the commissioning process associated with earlier generations of Viessmann boilers


025-W KEY FEATURES


 Pre-commissioned design requires only a five-minute flue gas sensor check before operation


 Available in 24 and 28kW outputs for large-scale domestic housing applications


 MatriX-Plus burner provides a 1:5 modulation ratio, adjusting output to match demand


 The 24kW model achieves ErP Class A and seasonal efficiency up to 98%


Vitodens 025-W, the Vitodens classic, simplifies matters further still, thanks to its standard fittings pack with male connections (while the 025-W comes with female connections). Aimed at independent merchants and installers serving the private domestic modernisation market, the classic also offers the lowest possible upfront price.


Space-saving For housing providers, property developers and homeowners, the benefits of both models extend beyond commissioning, however. Measuring just 300 x 400 x 700mm, they have been designed to fit into tight domestic spaces, including standard kitchen cupboards and smaller utility areas. This is particularly relevant for urban homes where it’s frequently the case that every inch counts. Additionally, all components


can be accessed from the front, meaning there is no requirement for side clearance. This can make a real difference when working inside a cupboard or other confined location. The boiler’s operating noise


Viessmann’s Vitodens 025-W combi boiler


has also been kept to 48dB for the 24kW model and 51dB for the 28kW version (equivalent to the hum of a fridge), which is ideal for bedroom-adjacent installations in flats and terraced housing. Installer experience suggests


that the compact sizing and pre-commissioned approach translate into practical benefits on site as well. Stuart Wall of Stuart Wall Heating & Plumbing, who works across Cheshire, North Wales and the Wirral, was among the first installers to fit the Vitodens 025-W after its launch. After recommending it to a customer as a low-cost option, he was pleasantly surprised by how quick and easy it was to install. “It was actually very straightforward. Everything was answered on the display. It went into a kitchen cupboard very easily.”


Quality components Importantly, the focus on simplicity and pricing does not mean the underlying technology has been stripped back. Both the Vitodens 025-W and Vitodens classic retain Viessmann’s corrosion- and temperature-resistant stainless steel Inox-Radial heat exchanger and MatriX-Plus burner system. This gives them the consistent combustion performance and durability associated with the wider Vitodens range, including the flagship 200-W. This is why both models come with a full five-


year warranty as well as a 10- year heat exchanger guarantee – a standout commitment at this price tier. On efficiency, the Vitodens


025-W achieves an ErP Class A rating of 92% and seasonal efficiency to DIN of up to 98%. The MatriX-Plus burner’s 1:5 modulation ratio means the boiler adjusts output to match demand rather than cycling on and off, reducing energy waste and wear. A householder replacing an aging boiler is likely to notice a clear improvement in running costs and system stability.


The perfect package? The launch of the Vitodens 025-W and Vitodens classic in February 2025 represented more than another addition to Viessmann’s boiler portfolio. It demonstrates how boiler design is increasingly being shaped around the realities of installation work, particularly in markets where productivity is critical. For installers who may have


previously viewed Viessmann as a technically excellent but time- intensive choice, the Vitodens 025-W could challenge that assumption. By combining pre- commissioning, a simplified setup process, front access and compact dimensions with proven Viessmann technology, it is designed to make getting the boiler onto the wall and on to the next job considerably easier. ◼ phamnews.co.uk/1026/39


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