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What is a cylinder thermostat?
... an explanation for householders.
A cylinder thermostat switches on and off the heat supply from the
boiler to the hot-water cylinder. It works by sensing the temperature
of the water inside the cylinder, switching on the water heating
when the temperature falls below the thermostat setting, and
switching it off once this set temperature has been reached.
Turning a cylinder thermostat to a higher setting will not make the
water heat up any faster. How quickly the water heats up depends
on the design of the heating system, for example, the size of boiler
and the heat exchanger inside the cylinder.
The water heating will not work if a time switch or programmer has
switched it off . And the cylinder thermostat will not always switch the
boiler off , because the boiler sometimes needs to heat the radiators.
Cylinder thermostats are usually fi tted between one quarter and
one third of the way up the cylinder. The cylinder thermostat will
have a temperature scale marked on it, and it should be set at
between 60°C and 65°C, then left to do its job. This temperature is
high enough to kill off harmful bacteria in the water, but raising the
temperature of the stored hot water any higher will result in wasted
energy and increase the risk of scalding.
If you have a boiler control thermostat, it should always be set
to a higher temperature than that of the cylinder thermostat. In
most boilers, a single boiler thermostat controls the temperature
of water sent to both the cylinder and radiators, although in some
there are two separate boiler thermostats.
The text below has been edited and approved by the Plain English
Campaign, who has issued a Crystal Mark to be displayed with it.
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Please note: The WP75-RF is a programmable cylinder thermostat.
