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How
to identify your system
Most
water systems in the UK are so-called "gravity" systems, where
the water from the mains is fed in to tanks in the roof and then fed into
the boiler, hot water cylinder and plumbing system using no more pressure
than the force of gravity. These systems are also called
"vented" or "tank and cylinder" systems.
Over
recent years, high pressure systems have been introduced. These keep the
whole of the hot and cold water systems under mains pressure. Most heat
the hot water using a "combination boiler". This provides a
continious but limited flow of pressurised hot water, with no stored water
in the system. Alternatively, they may use a conventional boiler and a
special unvented hot water cylinder designed to store hot water at mains
pressure.
Using the
guidance notes below, select the system in your house or, if you are still
unsure what you have, select the options for more information or consult a
professional plumber. You will have the choice to select from our
thermostatic range which works with any system.
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| Gravity Hot Water
system |
- Cold
water tank in the roof
- Lagged
hot water cylinder in airing cupboard
- Mains
pressure flow only from cold kitchen tap
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| High Pressure sysytem |
- No
water storage tank in the roof
- High
flow and pressure of water from all taps
- system
installed since 1986 (these systems were not used before this date)
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| Combination Boiler
system |
- No
hot or cold water storage in the house at all
- Commonly
used in 1-2 bedroom houses and flats
- Boiler
operates on demand
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More
Information about Gravity Hot Water Systems
What
it is and how it works A gravity system takes water from the
mains and stores it in a tank at the top of a building. The water is
then fed in to the plumbing system under gravity. The boiler is
supplied from the tank and the heated water is then stored in a
cylinder ready for use. This cylinder will commonly have foam
lagging round it and is commonly located in the airing cupboard.
Most houses in the UK have this type of system.
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Selecting
a shower for this system
- Choose
a mixer shower with a high flow rate to ensure a powerful flow.
- A
thermostatic shower is strongly recommended to avoid the risk of
scalding if a toilet is flushed or a tap turned on.
- You
can use a pump to improve the flow rate of this kind of system
Common
pitfalls to watch out for
- Selecting
a cheap imported shower which is only designed to work on mains
pressure. Choose only showers designed for the UK water system.
- Selecting
too large a showerhead or multiple outlets without a pump to achieve
the necessary water pressure to make these items work properly.
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More
Information about Mains Hot Water Systems
What
it is and how it works A mains pressure system takes water directly
from the mains and supplies it to both the hot and cold systems. For
the hot water, the mains is supplied direct to the boiler. The
heated water is then stored in a special hot water storage cylinder
built to withstand the pressures of mains hot water. These systems
were only introducted into the UK relatively recently. A typical
cylinder is called a "Megaflow", made by Heatrae Sadia.
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Selecting
a shower for this system
- Because
the water is at mains pressure already, the system requires no
pump to achieve power shower performance
- All
shower valves will give a reasonable performance as the mains
pressure will ensure a forceful flow of water
- We
recommend you use a thermostatic valve, but you may wish to
consider a Pressure Balancing Valve to achieve the same safe
showering
Common
pitfalls to watch out for
- You
cannot fit a pump to this system (it is illegal in the UK)
- Check
that the valve you use is rated for use up to the mains pressure
and fit a pressure reducing valve if needed.
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More
Information about Combination Boiler Systems
What
it is and how it works
A Mains pressure system takes water directly from the mains and
supplies it to both the hot and cold systems. The hot water is
heated as it is used by the boiler and therefore there is little or
no stored hot water in the system. This can limit the flow available
but is econonomical to run. This type of system in common in flats
or small houses where the low flow rate is not such a problem.
Multipoint water heaters are similar to combination boilers but only
provide water to taps and showers not radiators.
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Selecting
a shower for this system
- Because
the water is at mains pressure already, the system
requires no pump to achieve power shower performance.
- Most
showers give a reasonable performance, but some cheap
combi boilers have such a low flow rate that there can be
problems.
- We
recommend you use a thermostatic valve, but you may wish
to consider a Pressure Balancing Valve to achieve the same
safe showering.
Common
pitfalls to watch out for
- You
cannot fit a pump to this sytem (it is illegal in the UK).
- Some
valves are not compatible with some types of combination
boilers, particularly those with step modulating burners.
If in doubt call us or consult a qualified plumber to
check the compatibility.
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Electric
versus Mixer Showers
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 Before
you commit to an electric shower, you should consider the pros
and cons of mixers and electric showers. Electric showers have
advantages but they are not as cheap to install or run as they
may appear at first glance.
Use the guidance notes and then choose which option you want
to opt for.
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Mixer
Showers
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Electric
Showers
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Advantages
A much more powerful flow rate, especially if pumped
Neat, stylish appearance
Uses your existing hot water system, which can be more economical
than using electricity to heat the water
More reliable, with a longer guarantee
No need for a dedicated high capacity electrical supply
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Advantages
Heats the water continiously, so you never run out of hot water
Inexpensive to buy
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Disadvantages
Could run out of hot water if there is heavy demand on the system
More expensive to buy, though often cheaper to install
A mixer shower is the best system to have unless cost or water usage
is an issue
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Disadvantages
Flow rate is generally much lower than a mixer shower, especially in
winter when the incoming water supply is cold
More bulky in the shower than a mixer
Requires installation of a high capacity electrical supply direct
from your fusebox on its own dedicated circuit
A good option if you want something ecomomical or for a second
bathroom that is used at peak times only
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