Central Heating • Balancing a Heating System • Cleaning a Heating System • Instantaneous Electric Showers

Instantaneous Electric Showers

Electric showers
Electric showers are the easiest showers to install in terms of compatibility with existing water heating systems and locations throughout the home. They draw water direct from the mains water supply and heat it as it is used for showering. It can be used in most domestic showering applications e.g. over the bath, shower cubicles, shower rooms etc.

Provides a shower that is independent of the main hot water heating system in the house, thus reducing the risk associated with breakdowns.
Can be installed in almost any home throughout the UK new & old.
Instantaneous shower; it can be used at any time of the day.

Requires electrical wiring from the shower unit to the main fuse box.
Flow rate tends to be lower than showers that use the homes main water heating system, and it will vary between summer when the incoming water is warm, and the winter when the flow rate will reduce because the incoming water is significantly colder.
Cost wise, the installation costs may be higher than showers that use the homes main water heating system due to the need for plumbing and electrical work.

Higher kilowatt output showers have gone a long to help overcome some of the disadvantages of poor flow; (10 kilowatt showers are the equivalent of over 3 emersion heaters or 10 x 1 kilowatt bars on an electric fire) but to some an electric appliance fitted in the bathroom is perceived as a safety risk. This is not the case, providing it is properly installed, by a trained professional who knows what he is doing. Electrical appliances are often associated with water for example the kettle, washing machine or the electric cooker, which needs frequent washing.
If this is the shower solution for you make sure it’s fitted correctly and use a reputable brand that has an established reputation within the UK.

Information about the different types of shower systems...

Electric showers
Electric showers can be used with most domestic water systems. They are in most cases connected to the mains cold water supply; the feed pipe should have an isolation valve. This allows the valve to be turned off for maintenance if required.
The electrical connections to an electric shower are covered by many regulations. An electric shower must be installed on its own circuit s capable of providing the current necessary and must be rated above 60 amps. An RCD (residual current device) must be installed as, either part of your existing fuse board, or separately, interrupting the circuit to the shower. Connection to the fuse board should be by means of a MCB (miniature circuit breaker). Fuse, switch and cable ratings are also vital and we would suggest that 10mm cable is used for all installations. This makes upgrading your shower much easier in the future.
In all cases the circuit should be interrupted by a double pole pull cord switch with neon on/off indicator and a mechanical indicator should the neon fail.

Mixer showers
Mixer showers are so called because they will mix the existing hot and cold water, in a special valve, before it is available at the shower head. They are suitable for either low or high pressure (check with your supplier that the mixer valve you buy is suitable for the system you have). They are available as surface mounted fixtures, where the pipe work is easily installed on the top of your existing surface, or flush mounted, where the valve is seen, but the pipe work is hidden behind the surface. They are then ideal to install in a new shower cubicle construction where the pipes can be built into a wall.
To operate correctly both the hot and the cold water need to come from a source operating at the same pressure. Both can come from a mains fed system, (combi boiler or multi point water heater and cold mains) or both can come from tank fed water (immersion and cold storage tank). If one supply must come from high pressure and one from low pressure, a pressure balanced mixer valve can be installed.
A mixer shower will not increase the flow of water to your system. If your water flows from your taps at a poor rate, this is the rate it will feed the shower.
A drawback to installing a mixer shower is the fact that it will usually be connected to pipes which supply water to other points. When the other points are used (taps, toilet cistern etc) the flow rate to the shower will be affected. This in turn will affect the temperature of the water coming out of the shower and, in the case of the cold being drawn off elsewhere, could lead to scalding. This can be overcome, with a low pressure system, by laying separate pipes to the valve from both hot and cold supplies and making the shower water independent. You may need to contact a plumber for this as it will mean installing a special flange in the top or side of your hot water cylinder. In the case of a mains fed mixer a thermostatic valve is recommended. Mixer showers cannot be pumped from a mains pressure system (combination boilers, multi point heaters) but they can from low pressure systems. There are mixer shower valves especially designed for combination boilers, (pressure balanced mixer shower).

Thermostatic mixer showers
A thermostatic mixer shower incorporates a pre-set thermostat that will sense a dramatic change in temperature and rectify the situation. Some advanced thermostatic mixers will even cut the water off when a failure in flow is detected. Most thermostatic mixers also a have a temperature limiting device to stop very high temperatures being selected by the user.

Power showers
Power showers are mixer showers with integral pumps which increase the rate of flow from the shower head. They can only be installed on low pressure, tank fed systems. The cold water tank should be no less than 50 gallons acceptable for the shower alone. A dedicated hot and cold supply is necessary. The water supply must always be above the unit to ensure that the pump is always primed and does not have to suck any air.

Shower pumps
There are two types of shower pump. The first is a single impeller pump, with one driving blade which pumps the water, as it is mixed, to the shower head. This means of course it must go between the mixer valve and the head. The easiest place therefore to install the single pump is in the loft as it must be above the mixer valve. This can lead to problems with the cold temperatures in the loft freezing the water and it cannot be insulated because it needs a free air flow. For this reason a twin impeller pump was introduced. This is connected to both the hot and cold water before they reach the mixer valve and can be sited, ideally, in the airing cupboard. Most pump manufacturers will specify that the pump must be within 4 metres of the hot water cylinder and at least 30mm below the cold tank. Pumps, as with power showers, must have a dedicated water supply that serves no other outlets. They must also be connected to the hot supply with an anti aeration flange such as an Essex. An electrical connection is needed and should be taken from a switched, fused spur on a ring main outside the bathroom. It will be rated check manufactures instructions for amps.


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