The Vaillant ecoTEC Pro 24 is the smallest combi in Vaillant’s ecoTEC Pro range. It’s a wall-hung gas condensing boiler that heats your radiators and gives you hot water straight from the mains, with no tank or cylinder. It suits flats and smaller houses with one bathroom, where hot water is usually drawn at one tap at a time.
It’s still a current model in 2026. The version on sale today is the ErP-labelled ecoTEC Pro (model code VUW 246/5-3), and it shares the same compact casing as the 28kW and 30kW models. If you already own an older Pro 24, this review will help you decide whether a like-for-like swap is the right call or whether you should size up.
What Are The Vaillant ecoTEC Pro 24’s Key Specs?
The ecoTEC Pro 24 gives up to 24.8kW for heating and 9.6 litres per minute of hot water, and it’s A-rated for both.
| Specification | Vaillant ecoTEC Pro 24 |
| Boiler type | Gas condensing combi, wall-hung |
| Central heating output | 5.9 to 24.8kW |
| Hot water output | 23.4kW |
| Hot water flow rate | 9.6 litres per minute (at a 35°C temperature rise) |
| ErP rating | A for heating, A for hot water |
| Dimensions (H x W x D) | 720 x 440 x 338mm |
| Weight | Approx. 38kg |
| Fuel | Natural gas |
| Status | Current model, sold alongside the ecoTEC Pro 28 and ecoTEC Pro 30 |
What Is The Vaillant ecoTEC Pro 24?
It’s the entry-level 24kW combi in Vaillant’s mainstream ecoTEC Pro range.
Above it sit the ecoTEC plus, which Vaillant relaunched in a remastered form in 2023, and the premium ecoTEC exclusive. The Pro range keeps things simple: three outputs, one casing size and a straightforward control panel. Our Vaillant ecoTEC Pro range guide compares all three sizes side by side.
One detail catches people out. The number on a combi badge mostly describes hot water, not heating. The Pro 24 can put up to 24.8kW into your radiators, which is more than most small homes need. Its hot water output is 23.4kW, and that’s the figure that decides how many taps and showers it can keep up with.
Because it’s a combi, it only heats water when you open a tap. There’s no stored hot water cooling down in a cylinder through the day, and you get the airing cupboard back if you’re converting from an older system. If you’re still weighing up layouts, our guide to combi, system and conventional boilers explains the trade-offs.
What Features Does The ecoTEC Pro 24 Have?
The main features are a modulating burner, a hot water pre-heat, a compact casing, smart control compatibility and a clear fault display.
How Low Can The Burner Modulate?
It turns down to 5.9kW on heating.
On a mild day it ticks over at low output instead of firing hard, switching off and firing again. Fewer on-off cycles mean less wasted gas and less wear on parts.
What Does The Hot Water Pre-Heat Do?
It keeps a small amount of water inside the boiler warm, so hot water reaches the tap faster. That uses a little gas. If you rarely need instant hot water, you can switch it off from the control panel.
Will It Fit In A Kitchen Cupboard?
Usually, yes. At 720mm high, 440mm wide and 338mm deep, it’s the same height as a standard kitchen wall unit.
With the right service clearances it goes inside most cupboards, which helps in flats where wall space is tight.
Does It Work With Smart Controls?
Yes. It works with basic programmers and room thermostats, and with Vaillant’s own eBUS controls such as sensoHOME and sensoCOMFORT.
Add an internet gateway and you can run the heating from the myVAILLANT app. Vaillant controls can also add weather compensation through an outdoor sensor. Our smart thermostats page covers the options we fit.
How Does It Show A Fault?
The display shows an F code, which gives an engineer a quick starting point. Day to day, the same screen shows system pressure, temperatures and status. Our Vaillant error codes guide explains the common ones.
How Efficient Is The ecoTEC Pro 24?
It’s ErP A-rated for both heating and hot water, and Vaillant quotes an efficiency of around 93%. If you’re replacing an old non-condensing boiler, you should use noticeably less gas for the same warmth.
How the system is set up matters as much as the boiler. A condensing boiler only reaches its best efficiency when the water coming back from the radiators is cool enough to condense. A lower flow temperature helps with that, and so do good controls.
In England, Boiler Plus rules require a new combi to have time and temperature control plus one extra energy-saving measure. That can be weather compensation, load compensation or a smart thermostat with automation and optimisation.
Keep up the annual service. A blocked condensate trap or a dirty heat exchanger will push your gas use up over time.
What Are The Pros And Cons Of The ecoTEC Pro 24?
Its biggest strength is a compact, A-rated casing that fits most cupboards. Its biggest weakness is hot water: 9.6 litres per minute really only serves one tap at a time.
Pros
- Compact enough for most kitchen cupboards
- A-rated for heating and hot water
- Low minimum heating output of 5.9kW for steady running in mild weather
- Works with Vaillant smart controls and the myVAILLANT app
- Same casing as the Pro 28 and 30, so moving up a size later is simple
- Vaillant parts are widely stocked and familiar to most Gas Safe engineers
Cons
- 9.6 litres per minute is only enough for one outlet at a time
- Not suited to homes with two bathrooms
- No LPG version in the 24kW size
- Smart controls cost extra
- Usually only a small saving over the Pro 28, which has noticeably better hot water flow
What Size Home Does The ecoTEC Pro 24 Suit?
It’s best for flats and one or two-bedroom houses with a single bathroom and up to around 10 radiators.
It’ll run a shower well. If someone opens the kitchen tap at the same time, though, both will drop in flow.
Heating output is rarely the limit. At up to 24.8kW, the Pro 24 can heat a typical three-bedroom semi. Hot water is the real question. If your household often runs a shower while someone’s at the sink, the Pro 28 or Pro 30 will cope better.
Your incoming mains supply matters too. A combi can’t deliver more water than the mains provides, so a bigger boiler won’t fix weak water pressure. We check flow and pressure during the survey, and our guide on how to size a combi boiler goes into more detail.
How Much Does An ecoTEC Pro 24 Cost To Install In 2026?
A straight combi swap typically costs £1,900 to £2,600 fitted, rising to around £3,800 for a system-to-combi conversion.
These guide ranges include a standard flue, a magnetic filter, a chemical flush and basic controls. Your price depends on the job: the state of the existing system, flue position, gas pipe size, condensate route and the controls you pick.
| Type of job | Guide installed price |
| Combi to combi swap, same position | £1,900 to £2,600 |
| Combi swap with boiler moved or new flue route | £2,500 to £3,300 |
| System or regular boiler converted to combi | £2,800 to £3,800 |
These are guide figures only, and prices vary from job to job. A survey gives you a fixed price. For a wider breakdown, see how much a new boiler costs. If you’d rather spread the cost, read about boilers on finance.
What Are The Best Alternatives To The ecoTEC Pro 24?
For most two and three-bedroom homes, the ecoTEC Pro 28 is the better buy, with 11.1 litres per minute in the same casing.
- Vaillant ecoTEC Pro 28: same size casing and 11.1 litres per minute. We’d fit this in most two and three-bedroom homes.
- Vaillant ecoTEC Pro 30: 12.3 litres per minute for busier single-bathroom homes.
- Vaillant ecoTEC plus 826: the entry model in the remastered ecoTEC plus range, with a stainless steel heat exchanger, a wider modulation range and 10.6 litres per minute.
- Other brands: our best combi boiler reviews compare Vaillant with Worcester Bosch, Ideal and Baxi.
Is The Vaillant ecoTEC Pro 24 Worth It?
Yes, if you live in a small home with modest hot water needs.
It’s a well-built, compact combi from a brand our engineers know inside out, and parts are easy to get. The main caution is sizing. The price gap to the Pro 28 is usually small, so if there’s any doubt, the extra hot water flow is worth paying for.
Choose It If
- You live in a flat or a one or two-bedroom house
- You have one bathroom and rarely use two taps at once
- You need a compact boiler to fit inside a kitchen cupboard
- You’re replacing an existing ecoTEC Pro 24 that has served you well
Look Elsewhere If
- You have two bathrooms or an en-suite that gets heavy use
- Your home runs on LPG
- You want the wider modulation range and higher spec of the ecoTEC plus
- Your hot water demand is likely to grow, for example with a growing family
Get A Free Boiler Quote From Clever Energy Boilers
Clever Energy Boilers carries out new boiler installations for homeowners and landlords across the North West, Yorkshire and the Midlands. Our experienced, professional and registered installers check your hot water demand, mains supply and radiator count before recommending a size. That way you don’t pay for output you’ll never use.
Long, market-leading warranties are available through Clever Energy on the boilers we fit. We can also add a servicing plan to keep things running smoothly year after year.
Get your free, no-obligation boiler quote online in a few minutes.
Frequently Asked Questions
Is The Vaillant ecoTEC Pro 24 Discontinued?
No. The ecoTEC Pro 24 is still part of Vaillant’s current range in 2026, sold alongside the Pro 28 and Pro 30. The ecoTEC plus range above it was remastered in 2023, but the Pro range carries on.
Is 24kW Enough For A Three-Bedroom House?
For heating, usually yes, because the Pro 24 can deliver up to 24.8kW to the radiators. Hot water is the catch. With one bathroom and light use it can work, but most three-bedroom homes are better off with the Pro 28 or Pro 30.
Can The ecoTEC Pro 24 Run On LPG?
No. In the ecoTEC Pro range, the LPG version is the 28kW model. If your home uses LPG, see our page on LPG and oil boilers.
What Is The Difference Between The ecoTEC Pro And ecoTEC Plus?
The ecoTEC plus is the higher-spec range, with a stainless steel heat exchanger, a much wider modulation range and higher flow rates in the larger sizes. The ecoTEC Pro is simpler and usually cheaper, and suits smaller homes with one bathroom.
How Often Should The ecoTEC Pro 24 Be Serviced?
Once a year, by a Gas Safe registered engineer. An annual service checks combustion, cleans the condensate trap and keeps the boiler running safely and efficiently.