Hydronic Systems are typically installed external to the vehicle living space so that there is no risk of fumes leaking from the heater unit exhaust outlet, this is true. Most kits come with an external mounting bracket for this.
Please see Eberspacher Hydronic S3 Mounting brackets below:
- Heater Mounting bracket - Eberspacher Espar Hydronic S3 D5E D4E MOUNTING BRACKET 221000514200 | Butler Technik
- Water Pump Mounting Bracket - Eberspacher Espar Hydronic S3 D5E D4E Water pump BRACKET 221000513900 | Butler Technik