In the forced hot water system, fuel is used to heat the fluid. The water in the boiler will be hot; to prevent it from burning, it is better to wait an hour or two before opening the drain valve. Drain the water until it is clean; then close the drain valve, open the supply valve and turn on the oven. Newer systems need to be drained annually, but older systems collect sludge more easily.
With such a system, it may be necessary to drain more often. Identify the water inlet pipe that connects the boiler to the water supply pipes in the house. Locate the valve on the supply pipe and turn it to the closed position by turning it clockwise Locate the system drain valve, called the boiler drain. This simple faucet has threads for garden hose.
The drain will be near the bottom of the boiler, connected to a pipe or to the boiler itself. Connect a garden hose to the boiler drain and place it in the floor drain. Turn on the boiler drain by turning the knob counterclockwise. Watch for water to gurgle out of the hose.
You may need to call a professional to clean the system with chemical additives and extremely hot water. In addition to the energy stored in the hot water (storage tank), it is also possible to store thermal energy in the system in the form of unburned wood. If you have drainage, open the drain valve by turning the knob counterclockwise and drain the gallon or so of water remaining in the tank into a bucket. Most of these can operate at water pressures up to 50 to 60 psi and have threaded fittings to connect them to the distribution system.
Hot water circulates through pipes to radiators or heating panels that radiate heat to rooms. In addition to the boiler, pipes, radiators and circulation pump, hot water systems also have an expansion tank. This makes it possible to determine not only how much energy is lost between the tank and the load, but also how efficiently the radiators extract heat from the water. Dimensions are not given because the size and shape of the water storage tank and the necessary headspace for the combustion tubes limit the depth of the combustion chamber.
This publication provides the operator of a hot water heating system with important basic information about this type of system and its operation. The hot water tank must be vented to prevent pressure build-up when the water heats up and expands or turns into steam. Even though the water is already kept close to its maximum amount of heat, the operator can refill the combustion chamber just before leaving for the night. Heat from water in radiators or convectors is transferred first to metal radiators, and then to air.
By definition, a British thermal unit (BTU) is the amount of heat needed to raise the temperature of 1 pound of water by 1°F. These calculations assume that no heat is lost from the tank or pipes that carry water to and from the load. One of the problems most often encountered with hot water heating systems is the twisting of the combustion chamber doors. These calculations assume that the temperature of the water in the storage tank remains constant and that the 45° F temperature drop includes losses in the lines that carry water to and from the greenhouse.