Honeywell THM5421C1008 Benutzerhandbuch

68-0287—1

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Auto Discover is available when the TH9421C thermostat is 

connected to an EIM. The EIM communicates information to 

the thermostat. Thermostat settings can be specified using the 

up and down arrow keys on the screen or set to Auto Discover.

Some Installer setups are defaulted to Auto Discover. If not 

defaulted, the installer can change the option to Auto Discover, 

however, it is always important that the installer verify that the 

auto discovered values are correct for the system that is 

present.

When using the thermostat with an equipment interface 

module, Auto Discover will discover factory default settings 

and will not receive communications as to proper system 

settings. The equipment interface module is preprogrammed at 

the factory as a one heat one cool product and the thermostat 

will “auto discover” those settings. The equipment interface 

module will be reprogrammed when the installer manually 

changes the configuration in the installer set up. It is not 

recommended to use Auto Discover with an equipment 

interface module.

When using the VisionPRO® IAQ thermostat with a W8835 

zone panel, configure the zone panel, using the DIP switches 

on the panel, for the proper system settings. Enter the installer 

setup on each thermostat and assign zone numbers, and 

change the system settings (ISU 172–180) to Auto Discover 

(E) then press the discover button on the zone panel. The zone 

panel will then communicate those settings back to the 

thermostats and the thermostats will automatically configure 

the ISU settings in Auto Discover, again it is important to verify 

that the auto discovered values are correct.

NOTE: When a VisionPRO® IAQ thermostat is being added 

to an existing zoning system with T8635 Thermostats 

the new VisionPRO® IAQ must be set up as the Zone 

One Thermostat (master zone controller), and can 

only be used with a W8835 zone panel.

Follow these steps to enter the Installer Setup:

1. Press and release the System Key.

2. Press and hold the two blank keys on either side of the 

center blank key for approximately five seconds until 

screen changes.

3. Release the two blank keys when the screen on the ther-

mostat matches the screen below. 

DONE

MO

WE

TH

FR

SA

SU

USE ARROWS TO SET YEAR AND TIME

M22425

W

SCHED HOLD CLOCK SCREEN

FAN

ON

AUTO

A

M

THU

SYSTEM

EM HEAT

OFF

COOL

Following

Schedule

Inside

M23498

DONE

CANCEL

MO

MO

TU

WE

WE

TH

TH

FR

FR

S

SA

A

SU

SYSTE

M

EM 

HEAT

OFF

CHANGE FILTER UV LAMP 

Following

Schedule

Inside

Set 

OK TO PICK MULTIPLE DAYS    SCREEN LOCKED

M23499

DONE

M22442