Hydronic Forced Air
A hydronic (hot water) forced air and water heating system is a single system which provides centrally controlled heating, cooling, and ventilation along with hot water to a home. Hydronic systems are similar to the gas/electric split system except the conventional gas furnace is replaced with a hydronic forced air fan coil. Hydronic forced air delivers more even, comfortable heat while typically using less energy than even a highly efficient gas furnace.
How it works
This single relatively short appliance contains an air conditioning coil, a hot water coil and blower. The hot water coil is about 4 inches tall compared to a gas furnace heat exchanger at about 24 inches tall. There is no need for combustion air vents or a flue since the heat source is a water heater at a nearby location. There is no low limit on blower speed because there is no heat exchanger to overheat. This system invariably makes the heating system more quiet and maintains more even temperatures throughout the dwelling. The source of hot water is typically a tankless water heater operating at an efficiency of between 85 and 98%.