Hydronic, or hot water, heating has been standard for years in many parts of the U.S. It is seeing a surge in popularity at present, mainly because of the increasing use of radiant floor heating, which is known for providing even, comfortable heat.
Modern systems often use heated water rather than steam. This opens the system to the possibility of also using chilled water to provide air conditioning. In homes, the water loop may be as simple as a single pipe that “loops” the flow through every radiator in a zone. In such a system, flow to the individual radiators can not be modulated as all of the water is flowing through every radiator in the zone.
Slightly more complicated systems use a “main” pipe that flows uninterrupted around the zone; the individual radiators tap off a small portion of the flow in the main pipe. In these systems, individual radiators can be modulated.
Alternatively, a number of loops with several radiators can be installed, the flow in each loop or zone controlled by a zone valve connected to a thermostat. In any water system, the water is circulated by means of one or more circulator pumps. This is in marked contrast to steam systems where the inherent pressure of the steam is sufficient to distribute the steam to remote points in the system.
A system may be broken up into individual heating zones using either multiple circulator pumps or a single pump and electrically operated zone valves.
