Hot and Soft Running Water
Lime scale, a sediment which builds up and restricts the bore of pipework, can be a problem. A water softener, which can be a portable device or plumbed into the mains, can cure the difficulty. Gas and electric water heaters, the installation of which are also described, are prone to scale in hard-water areas. Used in conjunction with a water softener, the problems of scaling are eliminated.
There are four basic types of low-pressure electric water and storage heater. These usually consist of a copper cylinder inside an enamelled steel case.
‘Free-outlet’ or single-point heaters supply hot water to one particular place. It is possible to serve two adjacent points by means of a-arm arrangement. The most usual sizes have a capacity of around seven litres or 14 litres.
The main use is at kitchen sinks or wash basins where there is no alternative hot-or the hot-water source is a long way from a storage system and water would be wasted. Some free-outlet heaters are made in sizes of up to about 91 litres.
Cold water may be drawn from the mains, where the appliance is fitted over a kitchen sink, though supply can be taken from the storage cistern.
The local water authority should be informed if you want to supply the heater direct from the mains.
The heater works by drawing in cold water at the base of the cylinder, causing hot water at the top to spill out over a weir-type outlet. The design allows for the expansion of hot water.
Another type of low-pressure water heater possesses a pipe layout similar to that of a standard hot-water cylinder. Cold water from the storage cistern is heated by an immersion heater and vented back to the storage system by means of a draw-off pipe. Several draw-off points can be taken from the pipe run.
Low-pressure heaters must be connected to the cold storage cistern and not to the mains.
Some types have two immersion heaters, one in the upper section, for hand-basins, and the other in the lower section, working with the first, to supply hot water at times of greater demand; then both heat the entire heater water content.
Heaters can be both floor- or wall-mounted.
Where there is no other hot-water system, or where there is a limitation on head room which prevents the use of an independent storage cistern, a combination system can be used. As these incorporate their own cold-storage arrangements, these are usually more economic to install than a conventional water heater.
This pattern of heater must be placed above the highest draw-off point, otherwise it will not have the necessary head of water. The combination unit is a dual-purpose appliance, with an upper cold-water cistern and a lower hot-water sec tion, connected by a supply pipe at the bottom of the hot-water section.
A vent pipe, taken from the base of the top section, provides for hot-water expansion. Fitted with a conventional overflow connection from the cold-water section, the self-contained combination unit is completed with a cold feed which enters a ball valve from either mains or storage.
Where a combination unit is fitted, ensure that it has an adequate capacity, otherwise the low-capacity cold-water section may be emptied when demand is heavy.
A remedy is to reduce the flow of hot water, allowing the cold feed to keep pace, or increase the size of the unit, taking care to leave a safety margin. Combination units may be used in conjunction with indirect hot-water systems.
The cistern type of electric water heater works on the same principle as a combination unit. These are intended to be seen and usually encased in enamelled steel jackets.
The hot-water section in some models is insulated, as is also the division between the hot and cold sections. Heating is by means of an immersion heater and the hot water may be drawn off anywhere in the house. A wide choice of models is made.
The instantaneous water heater does not use storage arrangements. Incoming cold water flows over plates which contain electrical elements, heating the water.
Flow is regulated by the temperature of the water required. These heaters are not able to provide the full supply of a storage heater but are effective in providing localized hot water at a given point.
These have many advantages where used as heaters for showers or handbasins, and most models can be run directly from the mains or from a storage cistern, provided a sufficient head of water exists. Only a single supply pipe is needed, which makes installation cheaper.
Since you only heat water you are going to use and are not subject to the heat losses of a storage heater this type of water heating is competitive in running costs. There is no great difference in initial cost between a direct heater and a storage heater.
A 13A power supply is needed to serve electrical water heaters. This may be in the form of a fused spur from a ring-main circuit or an independent power circuit.
10. November 2011 by admin
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