
Water Systems - Gravity Fed.
The mains water enters the
property and flows through a stopcock before dividing into two pipes.
The stopcock can be anywhere but is usually found under the kitchen
sink. One of the pipes
takes water at
mains pressure (high pressure)
to the cold tap in the kitchen sink. This is the
best tap in the property to drink from. The other pipe runs up into the
roof space and fills a large
water tank called the main storage tank (MST) also called the cold water storage cistern
(cwsc).
If you have a large tank of water
in the loft,
then you probably have a traditional gravity fed low pressure water system.
Water from the main storage tank falls down through pipes which run to the toilet
cistern and cold taps in the bathroom. Tank water also runs through a pipe to
a
hot
water cylinder which is usually in the airing
cupboard. Hot water from the cylinder runs
through the hot water pipes to the hot taps in the bathroom and the hot tap at the kitchen sink.
Another pipe
called a vent runs
from the
hot water cylinder back up into
the loft
and over the cold water tank. The vent pipe has an open end. It is a safety feature
and must not be blocked. The hot water cylinder (direct or
indirect) is
called vented.
The system is called gravity fed
because it is only the weight of water falling
from the tank
which makes it flow through the pipes. The water is at a much
lower pressure than the mains
water (at the kitchen sink) and so a gravity fed system is also called a low pressure system.
The hot and cold water flowing to all the taps (except the kitchen sink - see
above) is at the
same low pressure and so the system is said to be balanced. A balanced system is
particularly suitable for showers
although the flow rate may need to be boosted by a pump.
The advantages of a gravity fed
low pressure system are
1. There is a tank of stored cold water which you can use if the mains
water stops running due to maintenance or a fault (but see below).
2. The system is balanced which is suitable for showers.
3. A pump can be used to increase the flow rate.
The disadvantages of a gravity fed
low pressure system are
1. There is a large tank of stored cold water in the loft which may
limit the use of space for storage of other items.
2. The flow rate without a pump is often too low for showers.
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