A combined system provides both radiant space heating and hot water heating for your home. Like air-to-water (hydronic) systems, combined systems are most suitable for new construction or for homes with an existing boiler and radiant heating system.
Heating mode:
- Outside air is drawn over a refrigerant coil in the outdoor unit
- Heat from the air warms the refrigerant
- The refrigerant is compressed to increase the temperature
- A heat exchanger in the outdoor unit transfers the heat from the refrigerant to the water glycol mix in a closed loop hydronic system
- Most systems use an indoor hydro box (also known as a flow control box) for controlling the flow of water glycol mix to each zone
- Your hydronic system warms your radiators, in-floor heating, and heats the water in your buffer tank
Cooling mode is a reverse of heating mode:
- Radiant slab cooling is possible, but its cooling output is limited and there is potential for water to condense and form mold
- Typically, a separate indoor fan coil unit (similar to a mini-split heat pump) is used for cooling