Baxi MainEco Compact 18kW Heat Only Boiler
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The Baxi MainEco Compact Heat 18 is a wall-mounted natural gas heat only boiler with an 18kW output, built as a straight replacement for old, standard-efficiency boilers on systems with a separate hot water cylinder. At 17.4kg installer lift weight in a 625 × 370 × 270mm casing, it hangs on an easy-fit bracket with front and side access for servicing.
Main is now Main by Baxi. Same boiler, same sales code (7712026), now sold under the Baxi brand.
Applications & suitability
Where it goes
A medium home on mains gas with an existing hot water cylinder and heating controls — kitchen cupboard or airing cupboard fit.
Typical job
A like-for-like swap of an old, standard-efficiency heat only boiler, keeping the cylinder, tanks and controls in place.
Works with / replaces
Runs alongside your existing hot water cylinder and external heating controls; the telescopic 60/100mm flue (315–500mm) covers most standard wall depths without cutting.
When not to choose this
It only does heating — you need a separate cylinder and external controls already on the system. For instant hot water from one unit, or a sealed system with the pump built in, choose the MainEco Compact Combi or System instead.
Key specifications
| Identity | |
| Brand | Baxi |
| Model | MainEco Compact Heat 18 |
| Boiler type | Heat only |
| Fuel | Natural gas |
| Performance | |
| Output (central heating) | 18 kW |
| ErP efficiency class | A |
| NOx class | 6 |
| Sound power level | 34 dB(A) |
| User adjustable CH temperature | 30–80 °C |
| Physical | |
| Dimensions (H × W × D) | 625 × 370 × 270 mm |
| Weight | 17.4 kg |
| Flue type | Telescopic concentric 60/100 mm (315–500 mm) |
| Electrical | |
| Electrical supply | 230 V / 50 Hz |
| Warranty | 5 years (registration required) |
Installation & compatibility
This is a gas appliance: installation, commissioning and servicing must be carried out by a Gas Safe registered engineer. It requires an existing hot water cylinder and external heating controls, which are not supplied. *The 5-year warranty applies subject to registration with Baxi after installation.
Related products
Baxi MainEco Compact Heat 24
The 24kW output for larger homes with a bigger radiator load.
View 24kW Heat OnlyIdeal for
Like-for-like heat only swaps in medium homes where the cylinder and controls stay put — light enough for a one-person hang. Next-day delivery nationwide or click & collect from our Reading trade counter.
