IMPORTANT: No user serviceable parts.
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 the 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 fitted 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 the water sent to both the cylinder and the radiators, although in some cases there are
two separate boiler thermostats.
What is a cylinder thermostat?
…an explanation for householders
42007492-001 R6
© 2010 Honeywell International Inc.
Honeywell Control Systems Ltd.
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existing under the laws of the UK and other countries. These intellectual and property rights may include patent applications, registered designs, unregistered designs,
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document replaces any previously issued instructions and is only applicable to the product(s) described. This product has been designed for applications as described
within this document. For use outside of the scope as described herein, refer to Honeywell for guidance. Honeywell cannot be held responsible for misapplication or the
product(s) described within this document.
Manufactured for and on behalf of the Environmental and Combustion Controls Division of Honeywell Technologies Sàrl, ACS-ECC
EMEA, Z.A. La Pièce 16, 1180 Rolle, Switzerland, by its Authorised Representative Honeywell Inc.
Fixing hooks
Pre-formed insulation
Locate mounting strap in cover slot
Hot Water
Cylinder
Screw hooks into strap and link together
to secure around cylinder.
Cut strap to size (if required) to ensure
thermostat is held firmly against cylinder.
6
Mounting
7
Fixing Strap and Hooks
9
Optional Manual Setting Knob (Non tamperproof option)
8
Temperature Setting (Tamperproof option)
Normal set point 60°
Important Note:
Ensure slot in knob is
aligned with arrow
then push home firmly
Important Note:
Ensure good clean
surface for thermal
contact.