Hot Water Storage Systems
Introduction
Traditionally, a hot water system within a property consists of 3 distinct elements; a boiler to heat the water, hot water tanks to store the heated water for taps & showers, and radiators to heat the property using water from the boiler.
For many of us, this is exactly how hot water is handled within our own homes, however advances in technology nowadays mean that one does not necessarily need to store hot water in order to still have hot water on demand, which is ideal for small dwellings which are short on storage space.
- All new gas boilers must be installed by a Gas Safe Registered installer, it is against the law for an unqualified individual to install any gas powered device.
- It is very important that gas appliances are installed and regularly checked for safety by a Gas Safe Registered installer. The Gas Safe Register recommends that you arrange safety checks on an annual basis.
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 tern 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.
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.
Further information and useful links
- Choosing a registered heating engineer
- Making sense of the energy efficiency ratings for your home
- Reduce your energy bills with solar panels
- Useful energy saving products
- More plumbing & Heating topics
- Find a Heating Engineer near you
- Find a Gas Safe Registered Installer (gassaferegister.co.uk)
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