Plumbworld has the lowest price for this product!


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


£24.14 (Inc. VAT)

23 Available

Also Worth Considering

Honeywell DT90E Wired Digital Room Thermostat

Honeywell L641A Cylinder Thermostat Reviews

Add your own review
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