What type of water system do I have?
Gravity fed system
This is the type of central heating system that most homes in the UK have. The gravity system consists of a cold water tank, which is usually found in the loft space, and directly below this, a hot water tank (usually in the airing cupboard).
If you have gas central heating you will have a gas boiler to heat the water, which is then stored in the hot water tank, and from this tank the hot water flows to the taps/shower etc. As the water in the hot water tank is used up, it is replaced with cold from the tank above, which in turn is ‘topped up’ from the mains water supply.
In an emersion system the hot water tank contains an element which heats the water to the required temperature (usually 60°C).
If the water pressure in the system is not sufficient enough to provide a satisfactory shower then a water pump can be added quite easily to this system. If you are thinking of adding a pump to your gravity system then you must bear in mind the size of your hot water tank. A 50 gallon tank is the standard for UK domestic requirements, however if you are using a pump, the water will be used at a greater rate, thus you must ensure that the tank is of a sufficient size to allow 2 or 3 consecutive baths or showers.
This is the standard solution many of us have in our homes, to provide hot water to taps and showers.
Water supply
The cold water is supplied to the vessel via a cold water storage tank, often located in the loft space directly above the hot water cylinder. A vent pipe runs from the top of the hot water cylinder and into the lid of the cold water tank above. This venting allows for the expansion of water in the cylinder via air bubbles and steam, and ensures the water is safely condensed to the cold water tank.
A standard vented system relies on gravity to supply hot water to the taps and shower(s), this means that the hot water cylinder must be located below the cold water storage tank, to generate the required 'head' of water pressure to adequately feed all the radiators.
Unvented hot water systems
In an emersion system the hot water tank contains an element which heats the water to the required temperature (usually 60°C).
If the water pressure in the system is not sufficient enough to provide a satisfactory shower then a water pump can be added quite easily to this system. If you are thinking of adding a pump to your gravity system then you must bear in mind the size of your hot water tank. A 50 gallon tank is the standard for UK domestic requirements, however if you are using a pump, the water will be used at a greater rate, thus you must ensure that the tank is of a sufficient size to allow 2 or 3 consecutive baths or showers.
This is the standard solution many of us have in our homes, to provide hot water to taps and showers.
Water supply
The cold water is supplied to the vessel via a cold water storage tank, often located in the loft space directly above the hot water cylinder. A vent pipe runs from the top of the hot water cylinder and into the lid of the cold water tank above. This venting allows for the expansion of water in the cylinder via air bubbles and steam, and ensures the water is safely condensed to the cold water tank.
A standard vented system relies on gravity to supply hot water to the taps and shower(s), this means that the hot water cylinder must be located below the cold water storage tank, to generate the required 'head' of water pressure to adequately feed all the radiators.
Unvented hot water systems
This is the standard solution many of us have in our homes, to provide hot water to taps and showers.
Water supply
The cold water is supplied to the vessel via a cold water storage tank, often located in the loft space directly above the hot water cylinder. A vent pipe runs from the top of the hot water cylinder and into the lid of the cold water tank above. This venting allows for the expansion of water in the cylinder via air bubbles and steam, and ensures the water is safely condensed to the cold water tank.
A standard vented system relies on gravity to supply hot water to the taps and shower(s), this means that the hot water cylinder must be located below the cold water storage tank, to generate the required 'head' of water pressure to adequately feed all the radiators.
Unvented hot water systems
A standard vented system relies on gravity to supply hot water to the taps and shower(s), this means that the hot water cylinder must be located below the cold water storage tank, to generate the required 'head' of water pressure to adequately feed all the radiators.
Unvented hot water systems
In this system the hot water tank is pressurised and takes in cold water directly from the mains supply, thus there is no need for a cold water storage tank in the loft. It’s easy to spot if you have an unvented system, as there will be a pressure expansion vessel on top of the hot water tank, and it will say ‘pressurised system’ on the tank itself.
Due to the pressurised nature of this system unvented hot water storage vessels are unsuitable for the addition of a pump, however as the water supplied directly from the mains is usually at approximately 2 bar of pressure, this is more than adequate for most purposes.
Combination boilers (or Instant Water Heaters)
These are often found in flats or small houses as they do not require a hot water tank or a cold water storage tank. This is because the boiler heats the water, as it is required, direct from the mains water supply.
A combination boiler is easy to spot if you are unsure which central heating system you have, as the boiler will fire up each time you turn on the hot tap.
A good modern combination boiler, combined with average mains water pressure, should provide hot water at approximately 1.5 bar, which is adequate for most purposes. As with the Megaflow system, this boiler runs direct from the mains water supply, thus making it unsuitable for the addition of a water pump.
Hot water pressure
What is bar?
Water pressure is measured in three common units: bar, psi and Head (m).
1 metre (3ft 3in) Head = 0.1 bar = 1.45 psi
You can calculate pressure by measuring the vertical distance in metres between the bottom of the cold water storage (header) tank and the water outlet (tap or shower). This figure is the water pressure in Head (m). Divide this by 10 to calculate bar.