Why Series Piping is a Must
In a series configuration, multiple tanks act as one large, stratified storage system. Cold water only enters through the cold water makeup tank (CWMU), ensuring a consistent, low-temperature return to the HPWH. This maximizes efficiency, keeps the heat pump operating in its optimal range, and prevents temperature mixing that can reduce performance.
The Hidden Flaw in Full Parallel Piping
A fully parallel piping layout might seem like a good idea, but it disrupts stratification, mixes water layers, and results in unstable return temperatures. HPWHs rely on a steady cold-water return for peak efficiency, and parallel piping can throw this off—hurting performance and increasing energy use.
Why Add Parallel Piping at All?
Here’s the secret: the parallel piping isn’t for daily operation—it’s for future maintenance. In a series-parallel design, the parallel lines are valved off during normal operation, forcing water through the series path. If a unit or tank needs to be serviced, the valves open, isolating just that section without shutting down the entire system. This keeps hot water flowing, minimizes downtime, and ensures reliability.