|
Ideal Building Inspections > Monthly Maintenance > Home Care E-Book > Hot Water Heating |
|
|
|
||||||||
Hot Water System |
|||||||||
 |
|||||||||
|
In this system water enters the boiler through a pressure-regulating valve. Heating is monitored by an aquastat or limit-control thermostat that shuts off the burner if the water temperature gets too high and shuts off the circulator if it gets low. An expansion tank helps control pressure buildup in the system, and a pressure-relief safety valve opens if water pressure in the boiler does rise too high. A combination gauge shows water temperature, pressure, and water level. The unit is largely self-regulating. The most common problems are circulator malfunctions and a waterlogged expansion tank. Hot water flows through the supply pipes to radiators or convectors. The water gives off heat and flows through the return line to the furnace. The circulator in the return line drives the flow in the system. In some systems various branches can be cut off with zone control valves. For servicing, there are drain valves for the boiler, the expansion tank, and the return line.
A steam boiler is essentially the same as a hot-water boiler, but it operates at a higher temperature and pressure. There is no pressure-regulating valve or expansion tank. Instead, there is a pressure gauge and an automatic safety control to shut down boiler operation if needed, as well as a relief valve that will blow off dangerous excess pressure. A glass water-level gauge shows the water level in the boiler; a shutoff valve in the water supply line permits manually adding water when necessary. (Some boilers have an automatic water feed.) A low-water cutoff automatically shuts down the boiler if the water level drops too far. A steam boiler operates at a higher pressure than a hot-water unit and has fewer components. The water level may need to be replenished at times because of evaporation through radiator air vents. Steam circulates to the room radiators or convectors by system pressure and convection; a circulator is not required. When it has given up its heat, the steam condenses and flows back to the furnace. Radiators and Convectors Radiators are cast-iron units of two to fifty sections, each with four or six tubes. Some models stand on the floor; others hang on wall brackets. Air must flow freely around all units in order to be heated. Convectors are pipes or tubes with closely spaced, thin metal fins. There are floor-standing, wall, and baseboard models. Each unit has an inlet valve. A steam valve must be fully open or closed; a screwdriver-adjusted hot-water valve can be opened partway to control the flow. Hot-water units have bleeder valves to purge air. With the system operating, open the valve with a screwdriver or key until water comes out, then close it. Radiators in single-pipe steam systems have screw-in air vents that let air out as steam enters. Some are adjustable; others have a fixed response temperature. Radiators in two-pipe systems have a steam trap at the return end that opens when the steam has given up its heat. Heating System - Inspection These regular inspections are performed on a regular basis and after a licensed technician has serviced the boiler and corrected any deficiencies that may be encountered during servicing.
Heating System - Servicing and cleaning An annual service should be performed by licensed heating technician. The following includes some of the tasks performed during this service. Older boilers should be put on a service contract, or a Heating Protection Plan if available in your area.
|
|||||||||
