In the "Hot" position, the unit maximizes the gas valve aperture and adjusts the water governor to achieve the highest possible temperature rise ($\Delta T$).
| Pros | Cons | |---|---| | High efficiency (condensing) | Requires condensate drain and potential neutraliser | | Compact wall-hung footprint | Sensitive to poor water quality/scale | | Modulating burner reduces fuel use | Some models can be costly to repair if major heat exchanger failure occurs | | Works with modern controls and smart systems | Requires correct sizing and commissioning for best performance | | Low emissions | Flue length/terminals limited by manufacturer | bosch+en153+hot
Bosch EN153 (also marketed under Bosch and Buderus lines) are high-efficiency wall-mounted condensing gas boilers widely used for domestic hot water and central heating. This post explains how they work, key features, installation considerations, troubleshooting common problems, maintenance, pros/cons, and buying tips. In the "Hot" position, the unit maximizes the
You cannot walk into an auto parts store today and ask for an "EN153." That number is obsolete. However, Bosch standardized its numbering system years ago. Bosch EN153 (also marketed under Bosch and Buderus
The direct modern successor to the Bosch EN153 Hot is the Bosch Super Plus W8AC.
When searching online for bosch+en153+hot, vendors on eBay or vintage VW forums (like TheSamba) will list NOS (New Old Stock) EN153 units. They are collector items and often expensive ($10-$20 per plug). Resist the urge to buy NOS. Rubber seals fail over 50 years. Buy the Bosch W8AC or NGK B6HS for modern fuel.