Keeping your water temperature just how you like it in your domestic hot water cylinder or pipes is essential, and the L641A Cylinder Thermostat from Honeywell will play a key role in this.

The L641A is designed to be surface mounted on your domestic hot water cylinders, and can be used to switch directly on a central heating circulating pump or boiler. Alternatively, this Honeywell thermostat can operate on a spring return or motor open/motor close zone valves.

Well suited to switching motorised zone valves, circulating pumps or boilers, this thermostat incorporates a bi-metallic temperature sensor and is double insulated for extra protection.

The L641A can be used with bare or pre-insulated cylinders, and installation is simple: just a plastic coiled wire is required for fixing.

The Honeywell L641A Cylinder Thermostat is perhaps the most cost-effective way in which to manage your water temperature at home.

Product information:

  • Suitable for use on uninsulated and foam-lagged cylinders
  • Double insulated
  • Power supply: 230v (50hz)
  • Temperature setting range: 50-80°
  • Cable clamp: Yes
  • Comes complete with optional control knob


CE Approved


Technical Drawings

£25.02 (Inc. VAT)

5 Available

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Honeywell L641A Cylinder Thermostat Reviews

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4.5/ 5
2 reviews
  • martinjh
    5/ 5

    Perfect fit to replace old one which had failed. Wired up exactly the same.Hope this one lasts as long as last one.

  • JDH
    4/ 5

    I was pleased to find that this was a direct replacement for the old unit that was the best part of 25 years old which made this a simple fit