Whenever a hydronic system is divided into several zones, it’s worth considering a buffer tank between the heat source and distribution system. This is especially true when the heat source is a single-speed “on/off” device rather than a modulating device.
One example is a 4-ton geothermal heat pump supplying several individually controlled panel radiators. Each radiator represents what I call a “micro-zone.” The output of such a zone is likely less than 10%, perhaps even less than 5%, of the heating capacity of the heat source. If you connect several such zones direct to a heat source, even one that can modulate down to say 20% of rated capacity, you’re likely to experience short cycling. This same reasoning holds true for an air-to-water heat pump.