
USER MANUAL
LX 420, 421
Table of contents
English ...................................................... 2 Français .................................................... 5
088L3353 - 01.01 57470

Product program
This user manual covers following thermostats with built-in GFCI
LXstat-420 Incl. fl oor sensor 3m
LXstat-421 With built-in room
Introduction
The thermostat is an electronic on/off thermostat for control of temperature by means
of an NTC sensor either placed externally
or internally in the thermostat. The thermostat has integrated a Ground Fault Circuit
Interrupter (GFCI, Class A). The thermostat
and the GFCI is a dual model suitable for
120/240 V 50/60 Hz supply.
The thermostat type LXstat-420 has an
external temperature sensor that is normally
placed in the fl oor construction. In this confi guration the thermostat
controls the temperature of the fl oor and
not the temperature within the room. The
thermostat type LXstat-421 has a built-in
temperature sensor. In this confi guration the
thermostat controls the temperature of the
room.
The thermostat has two adjustable set
points, one for the day operation and one
for the night setback temperature. Switching
sensor
1. Getting started
Buttons
between the two set points is easily done
with one push at the OK (
The temperature can be displayed in eigher
°C or in °F. Switching can be done on the pin
button marked with (
The thermostat has a pin button marked R,
allowing you to reset the thermostat to factory settings. These are listed at the end of
this manual with space for you to record your
settings.
) button.
)
A
B
C
D
E
I
H
A: Reset of GFCI
B: Red light indicating ground fault
G
C: Test of GFCI
F
D: Pin button ºC / ºF
E: Display
F: Reset to factory setting
G: Adjustment down
H: OK - accept
I: Adjustment up
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Display symbols
J
J: Clock function
Wake
Night
K: Heating on
K
Setting the thermostat into operation
Actual temperature setting is shown in the display and the thermostat is ready for use.
Comfort mode
To jump between the two set points press the OK (
Night, Setback
temperature
OFF
To change the temperature press UP ( ) or
) to increase or decrease the tempera-
DOWN (
ture. The display will fl ash for 5 seconds, and will
then show the new temperature setpoint.
) button
To change the temperature press UP ( ) or
DOWN (
) to increase or decrease the temperature. The display will fl ash for 5 seconds, and will
then show the new temperature setpoint.
To turn the thermostat OFF, press DOWN ( ) until
OFF appears in the display.
DO NOT USE THE TEST BUTTON ON THE GFCI
TO SWITCH OFF THE HEATING INSTALLATION.
The GFCI will automatically be reset after a disconnection of the mains supply
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