Yes, HVAC systems are necessary for radiant floor heating. Radiant floor heating systems rely on a boiler to heat water, which is then circulated through pipes in the floor. The heated water warms the floor, which in turn warms the air in the room. To ensure that the air in the room is comfortable, an HVAC system is needed to regulate the temperature and humidity levels. The HVAC system also helps to circulate the warm air throughout the room, ensuring an even temperature.