The Junkers JUNKERS HYDRO 4200 series is a compact, high-performance line of gas water heaters built for professional installers who need reliable, easy-to-service equipment. Designed for both residential and light commercial applications, this series delivers consistent hot water with minimal footprint. Whether you are fitting a new system or replacing an older unit, the HYDRO 4200 lineup offers straightforward commissioning and long-term durability.

Flexible Gas Compatibility

Installers can choose the exact model for the site’s fuel supply without extra adapters or conversions. The series covers natural gas (GZ 50) with the WRD 9-4KB 23, WRD 11-4KB 23, WR 11-4KB 23, and WR 9-4KB 23 units. For LPG sites, the WRD 11-4KB 31 comes factory-ready for propane, saving time and reducing on-site adjustments. This clear split between gas types means fewer stock-keeping units and faster project planning.

Installer-Friendly Design

Every unit in the HYDRO 4200 series is built with practical installation in mind. The compact casing fits into tight cupboards or utility spaces, while standardized pipe connections and clearly marked terminals speed up hook-up. The WRD models combine domestic hot water and central heating, while the WR models focus solely on water heating. Internal components are arranged for easy access, making routine checks, filter cleaning, and part replacements quick and hassle-free.

Reliable Performance & Efficiency

Consistent flow and stable temperature control are built into the core design. The series uses efficient combustion technology to deliver steady hot water even during peak demand, reducing temperature fluctuations and improving user comfort. High-quality heat exchangers and corrosion-resistant materials extend service life, while optimized gas consumption keeps running costs low. Fewer call-backs and predictable performance make these units a trusted choice for daily use.

Quick Model Reference

Use this guide to match the exact unit to your job. The WRD 9-4KB 23 and WRD 11-4KB 23 are natural gas combi heaters. The WR 11-4KB 23 and WR 9-4KB 23 are natural gas water-only units. The WRD 11-4KB 31 is the factory-ready LPG combi heater. WRD means combined hot water and heating, while WR is hot water only. The 9 or 11 shows flow capacity. KB is the connection layout. 23 is for natural gas (GZ 50), and 31 is for propane. Pick the right model, mount it, connect the pipes, and commission it quickly.