Several operational problems stem from the design rather than the heat pump itself.
Excessively small buffer
It does not provide enough inertia and cycling persists.
Excessively large buffer
It increases costs, response time, and thermal losses without necessarily providing any benefit.
Incorrect port connection
It can increase mixing or destroy stratification.
Incorrect pump selection
A large imbalance in flow rates between the primary and secondary circuits affects temperatures and overall efficiency.