Honeywell L641 Surface Contact Thermostat Instructions
L641
SURFACE CONTACT
THERMOSTAT
PRODUCT DATA
FEATURES
Version available for use as a cylinder thermostat in
domestic hot water installations
Version 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
DESCRIPTION
manual setting knob supplied (L641A)
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.
CE approved
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 fan-coil control
systems.
l641-en0r8444-uk07r0515
| General | Details |
|---|---|
| Name | Honeywell L641 Surface Contact Thermostat Instructions |
| Make | Honeywell |
| Language | English |
| Filetype | PDF (Download) |
| File size | 0.15 MB |

Honeywell T6 Pro Programmable Thermostat User Manual

Honeywell D1-528 Direct Thermostat Installation Guide

Honeywell FocusPRO P200 Programmable Thermostat User Guide

Honeywell RCHT8610WF Series Smart Thermostat Installation Guide

Honeywell T9 Smart Thermostat Installation Guide

Honeywell TH2320WF4011 FocusPRO Smart S200 Series Thermostat User Guide

Honeywell TL116A Thermostat Installation Guide

T10 Pro Smart Thermostat with Redlink Room Sensor

Honeywell TH6320WF2003 Lyric T6 Pro Wi-Fi Programmable Thermostat User Guide

Honeywell RTH2300 Thermostat User Guide

Honeywell L641 Contact Manual: Questions and Answers
Honeywell L641 Contact specifications
| Power supply | 230 V~, 50...60 Hz |
| Differential | Approximately 10 K non-adjustable |
| Dimensions | 44 x 79 x 54mm (1.73" x 3.11" x 2.13") |
Can the Honeywell L641 Contact be used for frost protection in heating systems?
Yes. The L641B pipe thermostat version is available for frost protection applications and should be mounted on the boiler return pipe in conjunction with the T4360A FrostStat. Instructions, p. 3
What's the difference between L641A and L641B on the Honeywell L641?
| Model | Design |
|---|---|
| L641A | Mounts directly onto domestic hot water cylinders |
| L641B | Mounts directly onto pipes |
What is the switch rating of the Honeywell L641 Contact?
4(2) A, 230 V~. Instructions, p. 2
What is the temperature differential on the Honeywell L641 Contact?
Approximately 10 K non-adjustable. Instructions, p. 2
How do I mount the Honeywell L641 cylinder thermostat?
The L641A mounts directly onto the cylinder using the fixing strap provided, positioned 1/4 to 1/3 of the way from the bottom after removing insulation and cleaning the surface. Instructions, p. 2
What does the S.P.D.T. Type 1CL switch action on the Honeywell L641 Contact mean?
The thermostat uses a snap-action micro switch actuated by a bimetal temperature sensing element to provide single-pole double-throw switching. Instructions, p. 1
Honeywell L641 Contact compared with other room thermostats
| Specification | Honeywell L641 Contact | BEOK TDR89 | BEOK TDS75 | BEOK TGW60 |
|---|---|---|---|---|
| Power supply | 230 V~, 50...60 Hz | 100 ~ 240V | 200 ~ 240V 50-60Hz | 100 ~ 240V |
| Differential | Approximately 10 K non-adjustable | ±1℃(Defaults adjustable 0.5-10℃) | ±1℃(Defaults adjustable 0.5-3℃) | ±1℃(Defaults adjustable 0.5-10℃) |
| Dimensions | 44 x 79 x 54mm (1.73" x 3.11" x 2.13") | 86x86x14mm | 86x86x15mm | 86x86x19mm |
















