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EN0R8444

  L641

SURFACE CONTACT

THERMOSTAT

PRODUCT DATA

FEATURES

 

Versions available for use as a cylinder thermostat
in domestic hot water installations

 

Versions available for use as a pipe thermostat in
fan-coil applications

 

Version available for use as a pipe thermostat in
frost protection applications

 

Version available for use as a pipe thermostat to
limit the supply water temperature in underfloor
heating and solid fuel systems

 

The S.P.D.T. switching action is accomplished by a
snap-action MICRO SWITCH which is actuated by a
bimetal temperature sensing element

 

The desired temperature control point is set by the
clearly scaled temperature selector on the front
cover

 

Wiring terminals are easily accessible

 

Tamperproof temperature setting (L641B)

 

Screwdriver slot temperature setting, with optional
manual setting knob supplied (L641A)

 

Approvals - B.E.A.B. (meets EN 60730)

DESCRIPTION

The L641 is a surface contact thermostat designed to sense
the water temperature in storage cylinders and water pipes,
and to provide temperature control, temperature limiting, and
temperature feedback functions.

L641A mounts directly onto domestic hot water cylinders and
can be wired to directly switch a wet central heating
circulating pump, or boiler, or to operate spring return and
motor open/motor close zone valves.

L641B mounts directly onto a pipe and can provide high limit,
low limit or frost protection in wet central heating systems or
automatic summer/winter changeover in XE70 and XE90 fan-
coil control systems.

Summary of Contents for L641AI039

Page 1: ...ector on the front cover Wiring terminals are easily accessible Tamperproof temperature setting L641B Screwdriver slot temperature setting with optional manual setting knob supplied L641A Approvals B E A B meets EN 60730 DESCRIPTION The L641 is a surface contact thermostat designed to sense the water temperature in storage cylinders and water pipes and to provide temperature control temperature li...

Page 2: ...cepting wires up to 1 5 mm2 Mounting The L641A cylinder thermostat should be mounted 1 4 to 1 3 of the way from the bottom of the domestic hot water cylinder after removing a section of the insulation and cleaning the surface The L641B pipe thermostat should be positioned less than 0 6 m 2 from the boiler or on a supply pipe to a fan coil unit close to the 3 port control valve IMPORTANT 1 The inst...

Page 3: ...m of the cylinder 2 The L641B should be mounted less than 0 6 m 2 from the boiler 3 The L641B should be mounted on the boiler return pipe and used in conjunction with the T4360A FrostStat 4 The L641B should be set to approx 25o C and mounted on the supply pipe close to the 3 port control valve such as to sense the water temperature even when the valve is closed APPLICATION High Limit For Underfloo...

Page 4: ...t to 25o C Set to 25o C WIRING DIAGRAMS L641A1039 DHWS ControL L641B1012 L641B1020 High Limit Terminal 2 used on Honeywell Y Plan systems Heating Load Timer Fan coil Unit Heating Load and existing controls L641B1004 Automatic Summer Winter Changeover XE90 Contacts C and 1 break on temperature rise L641B1004 Low Limit Frost Protection Connected to override existing time and temperature controls Con...

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