The principle of hydronic heat is simple. A hot liquid, usually water, is circulated continuously through piping to transfer heat to the air of a home. A sophisticated system that utilizes zig-zag loops of plastic tubing running under the floor to make the floor surface itself into a radiant heating panel is used in colder climates than ours. Also, old-fashioned radiators and baseboard heaters are an earlier version of hydronic heat technology.

   But the type that we have in our North Central Florida area utilizes the hot water created in the home’s water heater. It is piped into a cluster of finned pipes in a box placed above, or as integral part of, an air conditioning air handler (indoor unit) and in-line with the air flow into the ducts and registers around the home. An electronic solenoid valve opens when the thermostat requests heat to start the flow of hot water to heat the piping and warm the air flow.

   Here’s how one manufacturer describes the system: 

“Water from your hot water source is circulated through the coil unit while the central air system blows air through it. The air temperature is raised by 30˚ to 60˚ F while the water’s temperature is lowered about 15˚ to 30˚ F. The warmed air is delivered to your home and the water is returned to the source to be reheated.”

   Because the water is recirculated, the system does not increase water usage. The water heater is typically natural gas and a larger unit than normally required for a home without a hydronic heating system.

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  To learn more about heating and air conditioning systems, see these other blog posts:

• How can I find out the SEER of my air conditioner? 

• My air conditioner won't turn on. What's wrong? 

• How can I find out the size of my air conditioner? 

• How can I tell whether the condenser (outdoor unit) is an air conditioner or heat pump? 

• Where is the air filter for my central air conditioner and furnace? I can’t find it? 

• Does an old air conditioner use more electricity as it ages? 

• How did homes stay cool in Florida before air conditioning? 

• What is wrong with an air conditioner when the air flow out of the vents is low?

• Why has the thermostat screen gone blank? 

• Why does it take so long to cool a house when an air conditioner has been off for a while? 

• Why is my air conditioner not cooling enough? 

• What are the most common problems with wall/window air conditioners?  

• Will closing doors reduce my heating and cooling costs? 

   Visit our WATER HEATERS and HEATING AND AIR CONDITIONING pages for other related blog posts on this subject, or go to the INDEX for a complete listing of all our articles.