Yes, radiators are a type of HVAC system. Radiators are a type of convection heating system that uses hot water or steam to heat a room. The hot water or steam is circulated through a network of pipes and radiators, which transfer the heat to the air in the room. This type of system is often used in older homes and is still popular in some parts of the world. Radiators are an efficient and cost-effective way to heat a home, and they can be used in conjunction with other HVAC systems such as air conditioners and heat pumps.