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Honeywell L641A Cylinder Stat (40051)

Bi-metallic sensor. Surface-mounted. Control for boilers and wet central heating. Conforms to 89/336/EEC and 73/23/EEC. EN 60730.

  • Suitable for Uninsulated & Foam-Lagged Cylinders
  • Fixing Strap Included
  • Double Insulated
  • 1 Year Guarantee
  • Suitable for Uninsulated & Foam-Lagged Cylinders
  • Fixing Strap Included
  • Double Insulated

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£29.99INC VAT

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Honeywell L641A Cylinder Stat is rated 4.5 out of 5 by 13.
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Rated 5 out of 5 by from Simple, reliable and robust. Damaged the previous 10 year old thermostat by mistake. This is a direct replacement, simple to fit straight out of the box.
Date published: 2017-01-15
Rated 5 out of 5 by from Perfect replacement Bought this product to replace an older faulty one. Simple to install the new unit to the existing wiring (3 wires) and now all working as it should do!
Date published: 2016-12-14
Rated 5 out of 5 by from Seems v good Replaced a twenty-year old Potterton t.stat. Quick and easy. three wires to connect. Needed no earth. Looks robust plastic and metal.. Well-designed terminals and cable clamp. I checked the set temp with an IR thermometer and it was controlling to within a degree or so of the set temp.
Date published: 2016-09-22
Rated 4 out of 5 by from Honeywell Cylinder Stat. I have always used Honeywell stuff for central heating system controls and the cylinder stat is an easy wire, easy fit unit that I know will give good reliable service to my customer which is all you want for a business life free from call- backs.
Date published: 2016-09-09
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Does this use the same base plate as the old L641A1005 ? The base plate for the original is glued to the tank.

Asked by: Jafacake
The L641A1039, as with the L641A1005, does not have a detachable base plate. The unit is a one piece design with a removable cover. The product is a strap on unit, not glued to the cylinder.
Answered by: Honeywell Tech Support
Date published: 2017-07-31

Can this be used for underfloor heating to switch on the pump when heating goes over the set temperature on the pipe?

Asked by: PawelM
The L641A is designed to control hot water temperature in a cylinder. Whilst it could do the job there is a range of pipe thermostats that would be better suited. The L6190B2030 being the most likely solution.
Answered by: Honeywell Tech Support
Date published: 2017-07-26

How is this wired up?

There's no connector and I only have the old 4-wire (red/black/blue/yellow) cable to connect the three terminals Any idea which colour wire connects to which terminal for a Y-Plan system?
Asked by: YPlan
It is not possible to determine the connections by colour. A qualified heating engineer should be consulted.
Answered by: Honeywell Tech Support
Date published: 2017-06-03

How long should this last

Turning it down makes no difference to the water temperature, and feels extremely tight to turn. I just dont know what age to expect a fault to arise. ?
Asked by: Smudger4
It is not possible to provide a definitive answer. The Honeywell L641A can last many years. The operating environment can affect this.
Answered by: Honeywell Tech Support
Date published: 2017-06-03
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Specification
Brand Honeywell
Central Heating Control Type Thermostats
Insulation Type Double-Insulated
Manufacturer Guarantee 1 Year Guarantee
Model No L641A
Mount Type Surface-Mounted
Mount Type Surface-Mounted
Pack Size 1
Pieces in Pack/Case 1
Product Depth 55 mm
Product Height 85 mm
Product Type Cylinder Stat
Product Width 45 mm
Sensor Type Bi-Metallic Sensor
Sensor Type Bi-Metallic Sensor
Sensor Type Bi-Metallic Sensor
Suitable System Suitable for Uninsulated / Foam-Lagged Cylinders
Temperature Range 40 to 80 °C

Switch/contact rating: 4A resistive. 2A inductive. SPDT. Temperature range: 40°-80°C. H x W x D: 85 x 45 x 55mm.

Downloads

Instruction Manual