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Choosing the Correct Heating System

Shower Types and Jargon

Choosing the Correct Heating System

There are two main categories of heating system; Tradtional Boiler and Cylinder Systems and Combination Systems. Boilers in each system are used to both heat the hot water and provide the heat to the radiators. They differ in the way they heat the hot water, and in the type of radiator system. The traditional boiler and cylinder system can operate either an open vented or a sealed radiator system depending on the boiler type.

Traditional Boiler and Cylinder Systems
Heat Only and System boilers boilers are used to heat the radiators, as well as the domestic hot water that is held in a cylinder, usually located in an airing cupboard. This type of system is best if there is a high demand for hot water since the storage tank can absorb the impact of several hot water outlets being used at one time. Heat Only and System boilers can be an advantage over Combination Systems if the mains pressure is too low to produce a decent flowrate at an outlet in the property.

Traditional Systems can sometimes be converted to have sealed radiator systems by adding an expansion chamber to the circuit. System boilers come complete with this expansion chamber, sometimes built into the boiler, eliminating the need for the expansion tank in the loft of the property. They are space saving, less complicated to fit and are more efficient and a fully open vented traditional system.

Combination
Combination Systems use Combination, or 'Combi', boilers. Combi boilers heat the hot water on demand by a heat exchanger in the boiler. There is no need for a hot water storage tank. Installation is often quicker and cheaper than a traditional type system.

Combi boilers also have a sealed radiator system, that needs to be pressurised when the heating is off. There is no need for an expansion tank in the loft for the heating. Combination Systems suit a household where hot water is not in great demand. The mains inlet pressure determines the pressure of the hot water at an outlet.

Lack of a hot water storage tank and an expansion tank means that Combi systems occupy less space and can be easier to fit and maintain. Hot water is essentially an endless supply, although demand from several outlets at one time can reduce the flowrate at each. These systems are highly efficient because no heat is lost from water sitting in a storage tank, however in colder times there can be a delay in receiving hot water from a tap due to the initial inflow to the boiler being cooler. Combination systems are best suited for couples or small families where there is a low demand for hot water i.e. less than two bathrooms. Combi boilers are useful space savers because they don't require a hot water tank, so if the boiler is for a flat or a house with a loft conversion then a combi boiler would be the best choice.

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Shower Types and Jargon

Electric Showers
Electric showers take only a single cold water feed from the cold water supply. They heat the water by passing over a heating element inside the shower. The shower is ideal for families and households where there is a limited supply of hot water. Their performance relates to the kW output of the shower and the mains water pressure.

Mixer Showers
Mixer showers take water from both hot and cold water supplies. They mix the hot and cold to reach a desired temperature and can be used on any water system. They generally flow faster than electric showers and come with a manual or thermostatic valve. These showers are ideal for homes with a plentiful hot water supply.
If you have a low pressure gravity water system, you can make the flow more forceful by adding a pump.

Power Showers
Power showers take water from both the hot and cold stored water supplies. They mix the hot and cold to reach the desired temperature. They produce a more impressive spray force than mixer or electric showers, because an internal pump boosts the water flow. They are ideal for homes with a plentiful supply of hot water.
Not to be used on a mains water feed.

Electric Power Shower/Pumped Electric Shower
These showers are a single cold water feed electric shower that draws water from a storage tank; used in areas with low mains water pressure.
Not to be used on a mains water feed.

Shower Pumps
Shower pumps are used on stored water supplies to create an intense, fast-flowing power shower. They cannot be used on a mains cold water feed or combination boilers.

Digital Showers
Digital showers are the newest form of showering. The shower control and the water mixer have digital intelligence built-in. They take water from both the hot and cold water supplies and mix the water accurately to reach the desired temperature. They are available in pumped or high pressure version. Digital showers are ideal for homes with a plentiful supply of hot water.

Tower Showers
A shower valve with body jets on a single panel.

BIR – Built In Rigid: built in valve, rigid shower head.
BIV – Built In Variable: built in valve, variable shower head/riser kit.
BSM – Bath Shower Mixer: valve as a mixer on the bath taps.
BI/Built In – Built In Valve Only
ERD – Exposed Rigid with Diverter: A rigid shower kit and head with a diverter to a riser kit.
ER – Exposed Rigid: exposed valve with rigid shower head.
EV – Exposed Variable/Exposed Valve: exposed valve with the Mira shower comes with a variable riser kit.

HP – High Pressure: usually from pumped heating systems or unvented cylinders.
LP – Low Pressure: usually on gravity heating systems, mains pressure or vented cylinders.

kW – Kilowatt output of the shower.

Neg Head/Negative Head – The stored water source for the shower is placed below the shower head.
Pos Head/Positive Head – The stored water source for the shower is placed above the shower head and is the normal type of pump used in an installation. This is sometimes called a booster pump.

Single Impellor/Single End – One impellor to boost water supply; used for a single cold, hot or mixed water supply.
Twin Impellor/Twin End – An impellor for cold and hot water feeds.

Manual – The shower temperature is altered manually and can alter with changes in water supply and the temperature of the incoming water.
Thermostatic – The shower temperature stays at the temperature set, with the shower/valve taking account of changes in water supply and temperature of the incoming water.

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