Parallel and series layouts
A heat pump may operate in parallel with a boiler on a common header or preheat return water in series. Decentralised systems can serve a lower-temperature duty directly while the boiler retains the high-temperature network.
Give the heat pump useful hours
A heat pump is commonly assigned stable base load while the boiler meets peaks. Poor setpoints can cause both to fight, increase return temperature and reduce COP. Control philosophy should be written before commissioning.
Plan failure modes
Isolation valves, backup capacity, maintenance access, water chemistry and restart sequences matter as much as the normal flow diagram. A production plant needs to know what happens when the heat pump, source pump or control link is unavailable.
Sources
General technical explanation. No specific external source claims are made on this page.