Heat, but no ducts for air conditioning
Hydronic heating systems distribute heat by pumping water or a solution of water and antifreeze through tubing made from copper or a type of plastic called cross-linked polyethylene (PEX). Most systems rely on a boiler to heat the fluid. They typically burn fossil fuels, such as natural gas, heating oil, or propane. Dual-fuel boilers can burn either one of two fuels, cordwood or fuel oil, for example.
Other appliances are sometimes used to provide hot water, such as a heat pump, water heater, or solar collectors (see More About Hydronic Systems below).
Hydronic heating systems can include baseboard radiators, wall or ceiling panels, in-floor radiant tubing, fan-coil units, or a combination of two or three of these. Baseboard and free-standing radiators need relatively hot water — 160° F or higher — to operate while radiant-floor systems can heat a house with much cooler water temperatures.
Hydronic heating systems are clean and quiet
Because hydronic heat does not rely on the circulation of air, it does not move dust and other contaminants around the house. Most hydronic systems don’t use fans, either, so they don’t make much noise and they don’t create drafts. The pressure imbalances that forced-air systems can inadvertently create are not a problem with hydronic systems.
The big drawback with a hot-water heating system is that it’s limited to providing heat. Unlike a forced-air system, it doesn’t have ductwork that also can be used for mechanical ventilation, air filtration, central dehumidification, or (in most climates) air conditioning. If homeowners want an air conditioning system, it will have to be added separately.
In-floor radiant heat is unobtrusive
Radiant-floor heat usually relies on loops of plastic tubing embedded in the floor. (Some in-floor radiant systems use electric resistance coils embedded in…