Heat pump expansion vessel: Maintenance and practical checklist
Preventive maintenance of the "Heat pump expansion vessel" aims to stabilize pressure and absorb expansion in the heat pump circuit before major pressure fluctuations or leaks occur.
What you need to know
During periodic checks, the total water volume, buffer (where present), static height, and operating temperatures are examined. Initial settings are noted to provide a reference point.
Practical check
Pressure in heating mode, ΔP during defrost, pre-pressure, and cold pressure are monitored. Small, gradual changes may warn before total failure.
Common causes of problems
Early signs may be related to incorrect pre-pressure, air locks, or frequent pressure fluctuations. The small vessel also needs inspection.
Measurement and recording points
- Pressure in heating mode.
- Δp during defrost.
- Pre-pressure.
- Cold pressure.
Practical observation
In a heat pump, the additional volume of the buffer or hydraulic separator is also taken into account. For proper evaluation, we record the system temperature at the time of measurement, as pressure varies with temperature.
Safety
Before checking or disconnecting the expansion vessel, the hydraulic circuit must be isolated, safely depressurized, and confirmed to be free of dangerous pressure or temperature. Work is to be performed by a qualified technician.
Conclusion
In the "Heat pump expansion vessel", proper operation is evidenced by correct pre-pressure, appropriate vessel volume, and controlled pressure change between cold and hot states.