Vaillant ecoFit pure vs ecoTEC plus vs exclusive: which suits which home

Which Vaillant range should you fit?

The ecoTEC plus, for most jobs. It covers 26kW to 40kW as a combi, carries the five-year guarantee and takes the myVAILLANT connect gateway, so it answers the ordinary swap and the customer who wants app control. Drop to the ecoFit pure when the budget or the cupboard decides it, and step up to the exclusive when the customer is buying the top of the range. Every figure in the two tables below was read from Vaillant UK's product pages and installation manuals on 6 September 2026.

What flow rate does each Vaillant combi give?

Between 10.4 and 18.0 litres a minute at a 35 K rise across the two mainstream ranges, rising with output. Vaillant quotes two figures for every combi: the specific flow rate at a 30 K rise measured to EN 13203-1, which is the headline number the brochures carry, and the flow at a 35 K rise, which is closer to a real winter shower. Both come from the installation manual, so you can check them against the unit in front of you.

The restrictor column is the one that settles arguments on site. Vaillant fits a flow limiter to every combi, set to hold roughly a 42 K rise so the water stays comfortable in winter, which is why an 832 measured at the bath tap gives about 10.4 litres a minute rather than the 15.2 on the brochure. Vaillant calls it a flow rate limiter in the ecoTEC plus manual and a maximum water flow rate in the ecoFit pure manual. Same part, same purpose. The two exclusive combis carry GC numbers 47-044-66 for the 835 and 47-044-67 for the 843, and the 627 system boiler is 41-694-02.

What is the ecoFit pure best for?

Cost-conscious swaps in small to medium homes, and cupboards that will not take anything bigger. At 700 x 390 x 295 mm and 32 kg dry it is the smallest and lightest of the three, it takes a rear flue on every model, and all three combi outputs run a 10 metre 60/100 flue. The 25kW gives 10.4 litres a minute at a 35 K rise, which is one shower and not much else at the same time. What you give up is connectivity and guarantee length: Vaillant's own page lists the VRC 700 and VRT 350 rather than the myVAILLANT connect gateway, and the standard guarantee is two years against five on the ecoTEC plus.

Where does the ecoTEC plus fit?

Most homes, which is why it is the Vaillant engineers fit most. The remastered range keeps the case dimensions, boiler footprint, flue position and pipe connections of the outgoing models, so a like for like swap from an older 825 or 835 is deliberately painless. Combis run 26, 32, 36 and 40kW with the 940 storage combi on top, and system boilers run 10, 15, 20, 25, 30 and 35kW. IoniDETECT combustion monitoring, LINbus pump control and the semi-touch interface came in with the remaster, along with automatic LPG conversion through the interface on everything except the 840, 940 and 635.

The 940 is the one people forget. It is a 40kW combi with a 15 litre store built in, giving 18.0 litres a minute at a 35 K rise, and it is 580 mm deep and 60 kg dry against 352 mm and 36 kg for an 826. Measure the cupboard and think about the lift before you quote it.

When do you reach for the ecoTEC exclusive?

When the customer is buying the top of the range and the hot water demand is high. The exclusive carries Vaillant's Green iQ mark, an extra condensate heat exchanger, Quiet Mark certification on everything but the 43kW, and Vaillant states it is 85 per cent recyclable at end of life. The 843 is the highest output combi Vaillant sells at 43kW, giving 17.8 litres a minute at a 35 K rise, and Vaillant describes the 627 system boiler as the first UK Vaillant with an integrated diverter valve. Modulation is genuinely wide at 1:10.4 on the 835. It is also the heaviest and deepest of the three ranges, so check the wall and the cupboard first.

Which Vaillant boiler suits which home?

How long is the Vaillant guarantee, and what are the conditions?

Two years on the ecoFit pure, five on the ecoTEC plus and five out of the box on the ecoTEC exclusive, each extendable to ten. Those are the figures on Vaillant UK's own product pages on 6 September 2026. The extension is not automatic. Vaillant's homeowner pages tie it to installation by a myREWARDS installer with the boiler registered alongside either the Boiler Protection Kit or the Advanced Boiler Protection Kit filter. The professional site still carries the older Advance wording on the exclusive page, which steps 5, 7, 8 and 10 years by installer tier and filter, so quote the customer the tier you actually hold rather than the headline number.

The conditions that catch people out sit in the domestic boiler guarantee terms rather than on the product page:

• Register within 30 days of installation. Miss it and the guarantee reverts to 12 months from the date of installation, whatever the box said.
• Registration needs the full 28 digit serial number, which is on the data plate, the packaging, the removable stickers on top of the boiler and the back of the control box.
• Installation and commissioning must be by a Gas Safe registered engineer within six months of the boiler leaving Vaillant's warehouse.
• The Benchmark logbook must be completed at installation and left on site for inspection.
• The boiler must be serviced every year by a Gas Safe registered engineer and the service recorded in the Benchmark logbook. The cost of that service is not covered.
• The guarantee runs from the installation date, but only if there is proof of purchase or a completed Benchmark logbook. Without one it runs from the date of manufacture on the data plate, which can cost the customer months.
• Failures caused by contaminated water, sludge or flux residue make the visit chargeable, which is the practical reason the filter is tied to the ten-year offer.

How do you tell which Vaillant is on the wall?

• Read the data plate, not the paperwork. On the ecoFit pure the identification plate is on the underside of the case. The ecoTEC plus has two, and the one on top of the unit stays accessible once the boiler is fitted.
• The GC number is printed on the plate as GC no., and it is the number that pins the appliance down in the table above.
• The 28 digit serial number carries the build date: digits 3 and 4 are the year of production and digits 5 and 6 are the week, with digits 7 to 16 giving the product article number.
• Model numbers usually give the output in the last two digits, so an 826 is a 26kW combi and a 940 is a 40kW storage combi. Confirm it on the plate, because the naming has moved between generations.
• Article numbers are worth noting for ordering: 0010036015, 0010036016, 0010036017, 0010036018 and 0010036114 for the ecoTEC plus 826 to 940, and 0010020389, 0010020390 and 0010020391 for the ecoFit pure 825, 830 and 835.

Whichever tier goes on the wall, the paperwork is the same job every time. Manifold builds the CP12 and service record from the check on your phone, reads the make, model and GC number off the data plate with PlateScan, and keeps the property's appliance history ready for the next visit.