Combi boilers,system and heat-only boilers, air-source and ground-source heat pumps, biomass boilers, hydronic underfloor systems, zoned systems, high-voltage (switched live) systems, low current ((<3 A). Volt-free (dry contacts) systems, low current (<3 A). District and collective heating systems with accessible individual electric valve. Domestic hot water tanks. OpenTherm-enabled heating systems.