Hydronic systems
Hydronic systems use water or a mix of water and anti-freeze such as propylene glycol as the heat transfer fluid in a "closed-loop" that is recirculated between the floor and the boiler.
Various types of pipes are available specifically for hydronic underfloor heating and cooling systems and are generally made from polyethylene including PEX, PEX-Al-PEX and PERT. Older materials such as Polybutylene (PB) and copper or steel pipe are still used in some locales or for specialized applications.
Hydronic systems require skilled designers and tradespeople familiar with boilers, circulators, controls, fluid pressures and temperature.
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