A hydronic hot-water heating system circulates hot water to every room through baseboard panels. “Hydronic” is another term for forced hot-water heating. The hot water gives off its heat energy by utilizing fins attached to the tubing or channel carrying the hot water.
Baseboard panels mounted around the outer perimeter of the home provide a curtain of warmth that surrounds those inside. Radiant heat rays warm the room surfaces. Rising currents of convected warm air block out drafts and cold. Walls stay warm and cold spots are eliminated.
A boiler provides water between 120 and 210 degrees F. The water is pumped through the piping in the baseboard. Today’s boilers are very efficient and very small in size. Most units are the size of an automatic washing machine; some are as small as suitcases and can be hung on the wall, depending on the size of the home being heated.
Booster pumps are used to circulate hot water through the pipes. These pumps are designed to handle a
wide range of pumping capacities. They will vary in size from small booster pumps with a 5-gallon-perminute
capacity to those capable of handling thousands of gallons per minute.
There are two different piping arrangements utilized by the hydronic hot-water system: the series loop
and the one-pipe system, which is utilized in zoning. The zone-controlled system has two circulators that are
attached to a single boiler, and separate thermostats are used to control the zones. There are, of course,
other methods, but these two are among the most commonly used in home heating. The plumbing requirements
are minimal, usually employing copper tubing with soldered joints.
One-pipe systems may be operated on either forced or gravity circulation. Care must be taken to design and install the system with the characteristic temperature drop found in the heat-emitting units farthest from the boiler in mind.
The design of gravity circulation and one-pipe systems must be planned very carefully to allow for heat load and losses in the system. The advantage of the one-pipe system lies in its ability to allow one or two of the heat-emitting units to be shut off without interfering with the flow of hot water to the other units.
This is not the case in the series-loop system, where the units are connected in series and form a part of the supply line. The piping varies so that one allows the cutoff and the other does not. It is obvious that the series-loop system is less expensive to install because it has a very simple piping arrangement.
Hot Water for Other Purposes
It is possible to use the boiler of a hydronic heating system to supply heat for such purposes as snow melting, a swimming pool, domestic hot water for household use, and other purposes. Separate circuits are created for each of these purposes, which are controlled by their own thermostats.
Each is designed to tap into the main heating circuit from which it receives its supply of hot water. Hot water for household use, for instance, can be obtained by means of a heat exchanger or special coil inserted into the boiler.
Note that the supply water does not come in contact with water being heated by the boiler for the baseboard units and other purposes.
One of the disadvantages of the hydronic system is its slow recovery time. If an outside door is opened during cold weather for any period of time, it takes a considerable length of time for the room to once again come up to a comfortable temperature.
There is also noise made by the piping heating up and expanding and popping; it becomes rather annoying at night when you are in a quiet room and not too sleepy. The main advantage, however, is its economical operation. The type of fuel used determines the expense. The boilers can be electrically heated, heated with natural gas, or heated with oil.