An environmentally-friendly way of heating indoor spaces using water as a heat transfer mechanism. The Hydronic Heating Association states that not only is water the “ultimate transfer medium” but can also be much better for air quality. Older systems that use air can pass dust or other impurities through their system and pollute the air. Hydronic heating does not have this effect–producing cleaner air. The hydronic heating system is also quieter and can be less costly. Plastic tubing used in most hydronic systems are recyclable, adding to its green-living appeal.