MERLIN NX ROOM CONTROLLER – INSTALLATION & COMMISSIONING INSTRUCTIONS 
EN1Z-1035GE51 R0420  26   
LCD of a TR42x Configured to Display Info on Fan 
If 
OFF
 is displayed, the fan is switched OFF. Depending 
upon the given application configuration, the effective control 
mode for underfloor heating, radiator, ceiling heating, and 
ceiling cooling can then be switched OFF as well. 
 
Configuring the TR42x for Heating / Cooling 
With the TR42x, the user can select whether he wants to 
have: 
▪  cooling (
C
), 
▪  heating (
), or 
▪  cooling plus heating (auto) (
H/C
AUTO
). 
By doing so, inadvertent heating or cooling is prevented. 
Selecting "auto" results in automatic switching between 
cooling and heating. 
To make these selections, the user must enter the expanded 
menu (see section below). 
 
Expanded Menu 
The user can enter the expanded menu at any time (i.e., in 
any mode). This is done by touching both upper softkeys 
simultaneously (see Fig. 33). The "temperature" screen 
appears first. The user can scroll to further screens ("heating / 
cooling," "relative humidity," and "CO
2
 concentration") using 
the left (
) or right ( ) arrow softkey. 
NOTE:  The user can, at any time, exit the expanded menu 
using the upper left softkey (below the "
" symbol 
or the word "HOME") – or by simply waiting approx. 
60 seconds. 
In the expanded menu, the current temperature, relative 
humidity, and CO
2
 concentration can be displayed. 
The user can change automatic heating / cooling by scrolling 
(arrow softkeys) to the "heating / cooling" screen and then 
touching the upper right softkey, (below the "
" symbol or 
the word "EDIT"). The actual setting will then flash at 1 Hz for 
approx. 7 seconds, during which time the user can either 
cancel the given setting (upper left softkey, below the "
" 
symbol or the word "CANCEL") or confirm it (upper right 
softkey, below the "
" symbol or the word "DONE"). If no 
action is taken within this time, the given setting is auto-
matically confirmed. 
 
CLCMTR42xx CONFIGURED
TO DISPLAY SYMBOLS
OFF
H/C
UTO
2.0
°C
25.5
°C
C
C
C
C
41
603
%
ppm
%
2
CO
H/C
AUTO
H/C
UTO
C
FLASHES 7 SEC!
CTUAL
FLASHES 7 SEC!
FLASHES 7 SEC!
 
Fig. 33. Accessing the expanded menu