Honeywell Y9120W User Manual

User Guide

Y9120W Sundial RF2 Pack 4

How to use:
ST9120C Wireless Enabled Timer
CS92A Wireless Cylinder Thermostat

Honeywell Control Systems Ltd.

Arlington Business Park,
Bracknell
Berkshire
RG12 1EB

Technical Help Desk: 08457 678999
www.honeywelluk.com

50047645-002 A

© 2011 Honeywell International Inc.

System Components

Energy Efficiency and the Environment

Home energy use is responsible for more than ¼ of the total UK carbon emissions
which contribute to climate change. Heating and hot water systems based on
boilers account for of this figure, so it is important to understand how your
controls can help to maximize energy efficiency while maintaining your comfort.

Your Timer should be used in conjunction with appropriate temperature controls. In
order to save energy the following general points should be observed:

1. Ensure your system contains a room thermostat (where appropriate) and a hot
water thermostat, and that it is set to an appropriate temperature level, typically
20°C

2. Programme your heating (and hot water) to be off when you are not in the
house. If you are concerned about possible frost damage to any exposed pipe
work, it is advisable to fit a frost protection system – your installer can advise
you about this.

3. Think about how you use your domestic hot water – if you have a storage
system, it is not necessary to have this switched on all the time, even when you
are in the house.

4. Consider the heat up times required for your central heating. Every home
responds differently when the heating is switched on. Adjust the start time so
that you are not cold when you get up in the morning. A shorter heat up time is
required for other heating periods.

5. In the evening, when the house is up to temperature, it is often possible to
switch off the heating up to an hour before you go to bed, without any noticeable
reduction in comfort.

PLEASE RESPECT YOUR ENVIRONMENT!
Take care to dispose of this product and any
packaging or literature in an appropriate way

This document is to be left with the user

and forms part of a Home Information Pack

WHAT IS A PROGRAMMER?

...an Explanation for Householders (as recommended by the Energy Savings Trust)

Programmers allow you to set ‘On’ and ‘Off’ time periods. Some models switch the central heating and
domestic hot water on and off at the same time, while others allow the domestic hot water and heating
to come on and go off at different times. Set the ‘On’ and ‘Off’ time periods to suit your own lifestyle. On
some programmers you must also set whether you want the heating and hot water to run continuously,
run under the chosen ‘On’ and ‘Off’ heating periods, or be permanently
off. The time on the programmer must be correct. Some types have to be
adjusted in spring and autumn at the changes between Greenwich Mean
Time and British Summer Time. You may be able to temporarily adjust the
heating programme, for example, ‘Override’, ‘Advance’, or ‘Boost’. These
are explained in the manufacturer’s instructions. The heating will not work
if the room thermostat has switched the heating off. And, if you have a hot­water cylinder, the water heating will not work if the cylinder thermostat
detects that the hot water has reached the correct temperature.

WHAT IS A CYLINDER THERMOSTAT?

...an explanation for Householders (as recommended by the Energy Savings Trust)

A cylinder thermostat switches on and off the heat supply from the boiler to the hot water cylinder.
It works by sensing the temperature of the water inside the cylinder, switching on the water heating
when the temperature falls below the thermostat setting, and switching it off once this set temperature
has been reached.

Turning a cylinder thermostat to a higher setting will not make the water heat up any faster. How quickly
the water heats up depends on the design of the heating system, for example, the size of boiler and
the heat exchanger inside the cylinder.

The water heating will not work if a time-switch or programmer has switched it off. And the cylinder
thermostat will not always switch the boiler off, because the boiler sometimes needs to heat the
radiators.

Cylinder thermostats are usually fitted between one quarter and one third of the way up the cylinder.
The cylinder thermostat will have a temperature scale marked on it, and it should be set at between
60C and 65C, then left to do its job. This temperature is high enough to kill off harmful bacteria in the
water, but raising the temperature of the stored hot water any higher will result in wasted energy and
increase the risk of scalding.

Location

ST9120C

CS92A

(typically next to hot water cylinder, in bedroom)

This section is to be completed by the Installer

27

Keep this document in a Home Information Pack

This product and its associated documentation and packaging are protected by various intellectual
property rights belonging to Honeywell Inc. and its subsidiaries and existing under the laws of the UK
and other countries. These intellectual and property rights may include patent applications, registered
designs, unregistered designs, registered trade marks, unregistered trade marks and copyrights.

Honeywell reserves the right to modify this document, product and functionality without notice. This
document replaces any previously issued instructions and is only applicable to the product(s) described.

This product has been designed for applications as described within this document. For use outside of
the scope as described herein, refer to Honeywell for guidance. Honeywell cannot be held responsible
for misapplication of the product(s) described within this document.

Manufactured for and on behalf of the Environmental and Combustion Controls Division of Honeywell
Technologies Sàrl, ACS-ECC EMEA, Z.A. La Pièce 16, 1180 Rolle, Switzerland by its Authorised
Representative Honeywell Inc.

CONFIGURATION & SERVICE DATACS92A CONTROLS LAYOUT

Boiler & System Service Log

The space below can be used to provide a record of boiler & system services and
the names and contact numbers of the Installer and Service Personnel.

This information is important for a Home Information Pack.

Service/Installation
Date

Installation/Service
Engineer

Telephone Number /
Contact Details

ST9120C CONTROLS LAYOUT

Sensor element Transceiver

Green light
(under button)

Button

Red light
(under button)

3

Contents

CONTROL OF YOUR SYSTEM

General Description of Controls in Your System ...............................................4

The way to use a Timer .....................................................................................4

Your Cylinder Thermostat .................................................................................5

GETTING STARTED WITH YOUR ST9120C

Step 1: Setting the Date & Time .......................................................................6

Step 2: Running a Built-in Programme .............................................................7

PROGRAMMING YOUR ST9120C

The Built-in Programmes / Your Personal Programme......................................8

Reviewing the Programme Times .....................................................................9

Modifying the Programme ................................................................................9

Disabling / Enabling Time Periods .................................................................11

OPERATING YOUR ST9120C

Choosing the Operating Mode .......................................................................12

Overriding the Operation Without Changing the Programmes.......................12

The Extra Hour Function .................................................................................13

The Holiday Function ......................................................................................13

Enquiry Mode .................................................................................................14

FINE TUNING YOUR ST9120C

Changing from AM/PM Time Display to the 24 Hour Clock............................15

Changing the Installer Parameters .................................................................15

BOILER SERVICE REMINDER

Countdown to Service / When Service is Due ................................................18

Shut-down .......................................................................................................19

OPERATING YOUR CS92A HOT WATER THERMOSTAT

Basic Operation ..............................................................................................19

Battery Replacement ......................................................................................19

Error Indications .............................................................................................20

FAQ AND TROUBLESHOOTING

Frequently Asked Questions ..........................................................................21

Troubleshooting Guide ...................................................................................23

CONFIGURATION & SERVICE DATA (to be completed by Installer) .................26

4

General Description of Controls in Your System

Your Honeywell ST9120C provides timing control for your hot water system, letting
you set ON and OFF periods to suit your own lifestyle.

The ST9120C does not directly control the temperature but works together with a
CS92A wireless cylinder thermostat.

With 7-day programming and up to 3 on/off periods per day, every day can be set
differently.

ST9120C also has a Boiler Service reminder / Shut-down feature, which helps
ensure your gas boiler is regularly serviced in compliance with UK Gas Safety
Regulations. For more details see pages 18 & 19.

Your system includes a CS92A wireless cylinder thermostat and may include
other Honeywell wireless controls. These products use state of the art 2 way RF
communications to share information and give you robust and flexible control of your
indoor environment.

The following instructions explain how to programme and use the ST9120C, and
associated controls, to provide the most home comfort at the least cost.

The way to use a Timer

Think about the time periods when you are typically in the house and when you are not.
These are the times you should use as the basis for the programmes. It will be necessary
to allow some heat up time for the heating system after periods when it has been off – this
would typically be 1 - 1½ hours, depending on your house and your preferences.

Other features are commonly available on the Timer to enhance comfort and
convenience, for example, OVERRIDE, EXTRA HOUR, and MODE buttons.

A typical use of the OVERRIDE feature is when you return home unexpectedly for
the rest of the day and the hot water is off. Just press the OVERRIDE button and
the hot water will come on until the next programme time, at which point it will follow
the normal programme. The advantage here is that you do not have to remember to
switch off because the normal time programme does this for you.

CONTROL OF YOUR SYSTEM

5

A typical use of the EXTRA HOUR button would be if you returned to the house for
a short period when the hot water was off. Pressing the EXTRA HOUR button gives
you 1, 2, or 3 hours of hot water, exactly when you need it. Another typical use is
when the hot water is already on and you want it to stay on a little longer - just press
EXTRA HOUR and, for that day only, an hour will be added to the end of the time at
which hot water normally goes off.

The MODE button allows you to select how you want to operate your hot water. A
typical use of this feature would be if you take a mid-week day off work, you can
then set the MODE to ONCE to keep the system ON during the day from the first
programmed ON time till the last programmed OFF time.

Your Cylinder Thermostat

Your CS92A wireless cylinder thermostat measures the water temperature and signals
this to the ST9120C timer. The timer then performs all the necessary control actions to
maintain the water temperature at the set value. The set temperature is programmed by
your Installer in the ST9120C Installer Mode, and you should never need to change this.
A value of 60°C is typical.

CONTROL OF YOUR SYSTEM (CONT.)

6

Your ST9120C should have been set up to work correctly when it was installed.
However, the following will show you how you can modify your settings to meet
your particular lifestyle.

To assist you with programming and everyday use your ST9120C will display text
messages at every stage to help you get the most out of your central heating system.
The ST9120C uses LoT™ Technology to constantly update the display to give you
feedback about what is required.

Step 1: Setting the Date & Time

Your ST9120C had the date and time set at the factory, and these are normally
maintained by a backup battery in the event of power failures. If you wish to change
the date or time, or if the LoT™ Display shows the message ‘SET DATE + TIME’ just
follow the instructions below. Otherwise, go to Step 2.

a. Move the slider to the DAY/TIME position. The message ‘SET DATE + TIME’ will

show briefly on the screen, followed by ‘SET THE DAY’, and the day of the month
will now be flashing to indicate it can be changed.

GETTING STARTED WITH YOUR ST9120C

DAY/TIME

PROGRAMME

RUN

7

GETTING STARTED WITH YOUR ST9120C

b. To change the day of the month, press the or buttons until the correct

day is shown. Each press of the button will change the date by one day. As soon
as a change has been made, the message ‘IS DAY OK?’ will be displayed. Once
the correct day is reached, press the green button to confirm, and move to
the next step. If you do not need to make a change, just press the button
immediately and this will move you to the next step.

c. The month digits will now be flashing and ‘SET THE MONTH’ will be displayed. To

change the month, press the

or buttons until the correct month is shown.
The message ‘IS MONTH OK?’ will be displayed. Press the green button to
confirm the month is correct and move to the next step.

d. The year digits will now be flashing and ‘SET THE YEAR’ will be displayed. To

change the year, press the

or buttons until the correct year is shown. The
message ‘IS YEAR OK?’ will be displayed. Press the green button to confirm
the year is correct. If you have made a change and the date is a valid date, the
message ‘DATE SAVED’ will show and you can move to the next step. If the date
you set was not valid, for example 31 September, the message ‘INVALID’ will
show and you will be returned to the start of the date setting operation.

e. The time will now be flashing and the message ‘SET THE TIME’ will be displayed.

To change the time, press the

or buttons until the correct time is shown.
Each press of the button will change the time by one minute. Holding the button
down for more than a few seconds will change the time slowly at first, then
quickly. The message ‘IS TIME OK?’ will be displayed. Press the green button
to confirm the time is correct. If you have made a change, the message ‘TIME
SAVED’ will show, followed quickly by ‘DATE + TIME COMPLETE’.

f. Move the slider to the RUN position to complete setting the date and time.

Note: if the slider is moved at any time before the date and time have been set
correctly, the message ‘DATE UNCHANGED’ will be displayed briefly, and your
changes will not be saved.

Step 2: Running a Built-in Programme

With the date and time correct, your ST9120C Timer will now be operating to the
built-in programmes. These have been designed to provide hot water at typical times
throughout the day, but if you want to customise the settings, please see the next
section ‘PROGRAMMING YOUR ST9120C’ (page 8).

8

PROGRAMMING YOUR ST9120C

The Built-in Programmes

The built-in programmes give you a starting point that you can personalise to your
own requirements. Your Installer should have selected one and ticked the box
alongside it. If there is no tick, the product normally leaves the factory with Profile A
installed, but it is a simple matter to select one of the other profiles (see Changing

the Installer Parameters, page 15).

Built-in Programme (Profile A)

ON 1 OFF 1 ON 2 OFF 2 ON 3 OFF 3

Monday to Friday

6:30am 8:30am 12:00pm 1:00pm 4:30pm 10:30pm

Saturday & Sunday

6:30am 9:30am 12:00pm 1:00pm 4:30pm 11:00pm

ON 1 OFF 1 ON 2 OFF 2 ON 3 OFF 3

Monday

Tuesday

Wednesday

Thursday

Friday

Saturday

Sunday

Your Personal Programme

The table below has been left blank for you to record your own personal programme.

Built-in Programme (Profile b)

ON 1 OFF 1 ON 2 OFF 2 ON 3 OFF 3

Monday to Friday

6:30am 9:30am 12:00pm 1:00pm 4:30pm 11:00pm

Saturday & Sunday

6:30am 9:30am 12:00pm 1:00pm 4:30pm 11:00pm

Built-in Programme (Profile C)

ON 1 OFF 1 ON 2 OFF 2 ON 3 OFF 3

Monday to Friday

6:30am 7:30am 12:00pm 12:00pm 5:00pm 10:00pm

Saturday & Sunday

8:30am 9:30am 12:00pm 1:00pm 5:30pm 10:30pm

9

PROGRAMMING YOUR ST9120C

Reviewing the Programme Times

To review your programme, move the slider to the PROGRAMME position.

To review the programme times, press the

button repeatedly. The appropriate
ON and OFF markers will be displayed to show you which time is being reviewed.
Any of these times can be adjusted by using the

or buttons, and then

confirmed using the

button. Remember to return the slider to the RUN position

after reviewing is complete.

Modifying the Programme

The programme has three pairs of ON/OFF switching times per day. Each time can
be set between 3.00 am and 2.50 am (on the next day) to allow you to programme to
stay on past midnight, if required.

a. Move the slider to the PROGRAMME position. ‘SET PROGRAMME’ will show

briefly to verify this action.

b. ‘SET ON-TIME 1’ will then be displayed and the time setting for the first ON 1

time for MONDAY will now be flashing to indicate it can be changed. If you do
not wish to change the time, press the green

button and move to the next

step. If you do wish to make a change, use the

or buttons to change
the first ON 1 time. Each press of the button will change the time by 10 minutes.
As soon as the time has been changed, the message ‘ON-TIME 1 OK?’ will be
displayed. Press the green

button to confirm the time is correct and move to
the next step. ‘SAVED’ will be displayed for a moment to confirm that any change
has been saved to memory.

DAY/TIME

PROGRAMME

RUN

10

Note: When pressing the button the next ON or OFF marker may start to flash.
This indicates you have tried to set a time equal to one of the next programme times
already in the memory. Similarly, when pressing the

button the previous ON or
OFF marker may start to flash. This indicates you have tried to set a time equal to
one of the previous programme times. If this happens the ST9120C simply moves
both times together as long as you continue to press the

or buttons. Follow
the procedure in ‘Reviewing the Programme Times’ (page 9) to check and adjust
these times as necessary.

c.

‘SET OFF-TIME 1’ will be displayed and the first OFF 1 time will now be flashing. If
you do not wish to change the time, press the green

button and move to the next

step. Otherwise, use the

or

buttons to change the time. Press the green

button to confirm the time is correct and move to the next step. ‘SAVED’ will be

displayed for a moment to confirm that any change has been saved to memory.

d. The remaining ON and OFF times (ON 2, OFF 2, ON 3, OFF 3) can be set by

using the

or buttons to change the time, then the green button
to confirm the time is correct and move to the next step. If you do not wish to
change the time, just press the green

button to move directly to the next ON/

OFF time without making any changes.

e. After setting or reviewing the last off time, OFF 3, the message ‘COMPLETE’ will

be displayed to indicate the times for Monday have been set.

You now have a choice of how to set the programme for the next day:

Copying One Day’s Programme to Another Day (example Monday to Tuesday):

f. Whilst the day is showing Monday, Press the COPY DAY button. The message

‘COPY MON TO TUESDAY OK?’ will be displayed and the letters TUE will flash
to indicate the programme for Monday can be copied to Tuesday.

g. To select a different day to copy to, press the NEXT DAY button to cycle through

the days. With each press of the NEXT DAY button the message will change to
indicate the new day you are copying to.

h. When the required day is indicated, press the green

button to confirm, and
the message ‘MON COPIED’ will be displayed for a moment. The day into which
Mondays programme has been copied is now available to have its programme
edited.

Note: Once a day’s programme has been confirmed in this way, it now becomes the
day whose programme is copied if the COPY DAY button is pressed again.

OR

Programming a Different Day:

i. Press the NEXT DAY button to select the next day, which is displayed along the

top of the screen. The programme for that day can then be adjusted by following
steps b – e above. Programmes for the remaining days can be set in the same
way, using the NEXT DAY button to move to the next day.

PROGRAMMING YOUR ST9120C

11

PROGRAMMING YOUR ST9120C

Exiting Programming Mode:

To exit programming mode, move the slider to the RUN position. This can be done at
any time during the programming process, and any changes made and confirmed
with the button will have been saved.

Note: If the unit is left in Programming mode for more than 10 minutes without the slider
being moved or any buttons pressed, the message ‘MOVE SLIDER’ will be displayed.
Press a button to finish programming, or move the slider to the RUN position.

Disabling / Enabling Time Periods

To disable any of the time periods ON 1 to OFF 1, ON 2 to OFF 2, or ON 3 to OFF 3,
simply set the ON time and its paired OFF time to the same time, and the programme
will just ignore them.

To re-enable the time period, simply set the two ON and OFF times to be different.

12

OPERATING YOUR ST9120C

Choosing the Operating Mode

The operating mode may only be changed when the slider is set to the RUN position.

The symbol is displayed during a programmed on period. A green INDICATOR
LAMP shows when the system is switched ON.

A MODE button is provided to select the Operating Mode and therefore how the
system is controlled.

There are four possible Operating Modes; these are OFF, AUTO, ONCE, CONT.
Pressing the MODE button scrolls round these modes in sequence, and the display
indicates which mode is currently active.

• OFF mode

The system will remain OFF.

• AUTO (Automatic) mode

The system will be switched ON and OFF according to the programme.

• ONCE mode

The system will come ON at the first programmed ON time, and go OFF at the

last programmed OFF time.

• CONT (Continuous) mode

The system will remain ON continuously.

Overriding the Operation Without Changing the Programmes

In AUTO and ONCE operating modes, the OVERRIDE button switches the hot water
ON or OFF without altering the programme.

When the symbol is displayed, pressing the OVERRIDE button switches the
system OFF until the next programmed ON time.

If the symbol is not displayed, pressing the OVERRIDE button switches the
system ON until the next programmed OFF time.

The LoT™ Display will provide you with information about the override.

13

OPERATING YOUR ST9120C

The Extra Hour Function

The EXTRA HOUR button allows you to switch the

system

ON for up to 3 extra hours
without altering the programme. Pressing the button once will give one extra hour.
The LoT™ Display will display the message ‘+ 1 HOUR’, to confirm the button has
been pressed.

When the system is OFF (the symbol is not displayed), pressing the EXTRA
HOUR button switches the system ON for just one hour.

When the system is

ON (the symbol is displayed), pressing the EXTRA HOUR

button extends the programmed ON period by one hour.

Further presses of the EXTRA HOUR button will increase the extra hour period by
one hour for each button press, up to a maximum of 3 hours. The LoT™ Display will
continue to provide information on the extra hour status.

To cancel the extra hours, just keep pressing the EXTRA HOUR button until the
‘CANCELLED’ message appears on the LoT™ Display.

The Holiday Function

The Holiday function allows you to switch off your

system

for a specified number of
days (from 1-99 days). This lets you save energy and related costs when you are
away from home, but resumes normal operation on the day of your return.

To set the Holiday function:

a. Ensure the slider is in the RUN position, then press the HOLIDAY button once.

The message ‘SET HOLIDAY’ will appear briefly, followed by ‘SET DAYS AWAY’.

b.

Use the

or

buttons to set the number of days you will be away. The display
will show the number of days, and this number will be flashing to indicate it can be
changed. The day of the week will also keep changing to show the day you return.

c.

If you have made a change to the number of days, the message ‘DAYS AWAY OK ?’
will appear. Press the green

button to confirm your selection.

d.

The message ‘SAVED’ will be displayed for a few seconds, followed by the date you
return, to enable you to check you have programmed the holiday function correctly.

e. During the holiday period, the LoT™ Display will show the message ‘ON

HOLIDAY’ and the display will count down the number of days till you return.

To cancel the Holiday function:

f. To cancel the Holiday function, just press the HOLIDAY button again. The LoT™

Display will show ‘CANCELLED’ and the unit will return to normal operation.

Note: while setting the Holiday function, if there is a gap of more than 1 minute
between button presses, the function will cancel itself automatically and return to
normal operation.

14

OPERATING YOUR ST9120C

Enquiry Mode

As the heart of your system, the ST9120C has access to temperature information
from the other system components, and allows you to enquire about this information.

To enter Enquiry Mode, ensure the slider is in the RUN position, then press and
hold the

button for 4 seconds.

The LoT™ Display will show the message ‘INFO MENU’ to confirm that you have
entered Enquiry Mode.

Pressing the

or buttons then allows you to step around and view the available
information. The LoT™ Display will continue to update to tell you what information
is being viewed, and the main display will show the value. If the information is not
available, the display will show dashes -- -- instead of a temperature value. The table
below shows the type and sequence of information available in Enquiry Mode.

To exit Enquiry Mode:

If the button is not pressed for 30 seconds, your ST9120C will return to RUN mode.

Information LoT™ Message Other display symbols

* Room temperature ROOM TEMP

* Room temperature setting ROOM SET

Ŧ Hot water temperature WATER TEMP

Ŧ Hot water temperature setting WATER SET

* This information will be available if you have a room temperature control system, with a DT92E

room thermostat.

Ŧ

This information will be available if you have a hot water control system, with a CS92A hot water sensor

15

FINE TUNING YOUR ST9120C

Changing from AM/PM Time Display to the 24 Hour Clock

Your ST9120C can operate on the 12 hour AM/PM or 24 hour clock formats. To
change the format, ensure the slider is in the RUN position then press and hold the

and buttons together for about 2 seconds. Ignore the ‘NOT VALID’ message
that will appear briefly. Then the displayed times will be changed automatically to
the new format.

Repeating this procedure will change the clock display back to the original format.

Changing the Installer Parameters

The ST9120C has a special Installer Mode where some features can be adjusted
to suit your lifestyle or preferences – these are called Installer Parameters, and are
listed in the table below, along with a description of the options that are possible.

Your installer should set this up for you to suit your application (see CONFIGURATION
& SERVICE DATA section). However, you may wish to alter some of the settings
yourself, and this section shows you how to do this.

Note: some parameters indicated by * are not used used if your system is only
controlling the hot water.

INSTALLER
PARAMETER

Parameter

Number

Default

Value

Options Description

24hr or am/pm
clock display.

1 12 12, 24 12 = am/pm display

24 = 24hr display

Configure backlight
operation.

2 2 0, 1, 2 0 = off

1 = on if button pressed
2 = on continuously

Enable/disable auto
time change.

3 1 0, 1 0 = disabled

1 = enabled

1-day or 5/2-day or
7-day operation.

4 7 1, 5, 7 1 = 1-day operation

5 = 5/2-day operation
7 = 7-day operation

Number of ON/OFFs
per day.

5 3 2, 3 2 = 2 on/offs per day

3 = 3 on/offs per day

Select default time
programme.

6 A A, b, C A = standard

b = at home
C = economy

Set hot water
temperature

8 60°C 40 to

85°C

Stored hot water set
temperature

16

To Enter Installer Mode:

a. Ensure the slider is in the RUN position, then press and hold

and buttons
together for 8 seconds. Ignore the ‘NOT VALID’ message that is displayed for a
few seconds. The message ‘SET UP MENU’ will show briefly, followed by ‘SET
INSTALLER OK ?’

b. Press the

button to take you into the Installer Mode Parameter Menu.

c. Parameter 1 is now available to change. This is to allow you to change the

clock format from 12 hour AM/PM to 24 hour. At every step, the LoT™ Display
will inform you what the parameter means and what option you have selected.
The parameter number is shown on the display separated by a colon from the
parameter value.

d. You can change the parameter value by pressing the

or buttons. At this
point the description in the LoT™ Display will change and the parameter value
will flash. If you press the value will stop flashing and be saved for use.

INSTALLER
PARAMETER

Parameter

Number

Default

Value

Options Description

* Optimum start

9 0 0, 1, 2 0 = no optimum start

1 = delayed start
2 = optimum start on

* Optimum start limit 10 1 1, 2, 3 1 = 1 hour

2 = 2 hours
3 = 3 hours

* Optimum stop

11 0 0, 1 0 = disabled

1 = enabled

* Frost protection
temperature

12 5 5 to

16°C

Frost protection
temperature

* Minimum ON/OFF
time

13 1 1, 2,

3, 4, 5

mins

Minimum ON/OFF time
in minutes

* Cycle rate

14 6 3, 6, 9, 12Number of boiler cycles

per hour

* Proportional band
width

15 1.5 1.5 to

3.0°C

Width of control
proportional band in °C

Failsafe mode (loss of
RF communications)

16 0 0, 1

0 = off
1 = heating on 20%

Reset all parameters

20 1 0, 1 0 = do not reset

1 = default parameters

FINE TUNING YOUR ST9120C

17

FINE TUNING YOUR ST9120C

e. Press to move to the next parameter available for editing.

f. Keep pressing

to step around the list of parameters, and use or

buttons to change the parameter value.

g. Any parameter changes that have been confirmed with the

button will be

saved and used.

To Exit Installer Mode:

h. You can exit Installer Mode at any time by moving the slider to the next position

and then back again to RUN.

Note: Installer Mode will exit automatically after 10 minutes if the slider is not

moved.

18

BOILER SERVICE REMINDER

If your house is rented, by Law, your gas boiler should be inspected once a year to
ensure it is operating safely. Your ST9120C Timer has a range of features designed
to help make sure this service is carried out at the correct time. These features will be
programmed by your Installer, Maintenance Engineer, or Landlord.

• If it hasbeenset todoso, ST9120C willdisplay a messageon the screento

remind you that a boiler service is due.

• Iftheserviceisoverdue,theTimermayswitchofftheheatingsystem,toensure

your safety. If this happens you must arrange an immediate service visit. Contact
details should be listed on page 26 of this guide, in the section Boiler & System
Service Log.

• AcontacttelephonenumbermayalsohavebeenprogrammedintotheST9120C.

If so, a message will appear on the LoT™ Display indicating the number you
should call.

Countdown to Service

Your ST9120C can indicate a countdown for the
number of days until your service is due. This
message will appear on the screen every few
seconds, to give you an opportunity to schedule
a service visit.

When Service is Due

When your boiler service is OVERDUE the words
“SERVICE DUE” will continue to flash on your

screen, and you should arrange an immediate
service visit.

19

Shut-down

If your ST9120C shows the words “SERVICE
DUE” and “OFF” then your boiler service is
overdue and the boiler has been automatically

switched off to ensure your safety – you should
arrange an immediate service visit.

If set to do so, it may be possible to obtain limited
use of the boiler by pressing the EXTRA HOUR
button. Each button press will allow operation of
the boiler for 1 hour at a time, and the screen will
display the message “On 1h” as shown. However,
you should still arrange an immediate service visit,
as this will allow you to comply with the law and
ensure your gas boiler is operating safely.

BOILER SERVICE REMINDER

OPERATING YOUR CS92A HOT WATER THERMOSTAT

Basic Operation

Your CS92A consists of a sensor element that
is strapped to the metal surface of the hot
water cylinder and a wireless transceiver box
that is normally mounted on a wall surface
apart from the cylinder. The transceiver
communicates with the ST9120C programmer
and regularly sends the hot water temperature
measurement to it.

Battery Replacement

The CS92A batteries should last for a minimum of 2 years. Well before they run out,
CS92A will communicate with ST9120C and it will show the message ‘SENSOR LOW
BATT’ whilst also flashing the tap symbol.

Batteries are accessed by
unclipping the front cover
at the bottom. Note battery
polarity. Reverse process
to refit front cover.

Use 2xLR6 (AA) alkaline
batteries only.

1

2

Sensor element Transceiver

20

Error Indications

To save battery power, CS92A will indicate
error conditions on the LoT™ Display of
ST9120C. It is possible to view the CS92A sta­tus by pressing the button on the transceiver
box. The lights underneath this button will
provide feedback as shown in the table. Go
to the FAQ AND TROUBLSHOOTING section
for more information.

Green Light Red Light Status

On Flashes up to 5 times in

succession, then repeats

Everything is OK, red light shows signal
strength - press button again to exit

Off Flashes 0.1 s on, 0.9 s off Battery low condition, replace batteries

Off Flashes 0.5 s on, 0.5 s off Sensor error, check sensor connection

Off On continuously Loss of communications

21

FAQ AND TROUBLESHOOTING

How do I set the time only, if the ST9120C clock is not correct?

Your ST9120C contains an accurate digital clock that is factory set. Should you ever
need to change the time, just follow this procedure:

a. Move the slider to the DAY/TIME position.

b. Keep pressing the green

button until the message ‘SET THE TIME’ is

displayed. To change the time, press the

or buttons until the correct
time is shown. The message ‘IS TIME OK?’ will be displayed. Press the green
button to confirm the time is correct. If you have made a change, the message
‘TIME SAVED’ will show, followed quickly by ‘DATE + TIME COMPLETE’.

c. Move the slider to the RUN position, to complete changing the time.

What do I do when the clocks go back in October and forward
in March?

Your ST9120C is factory set to change the clock automatically at the correct dates,
so you should never need to adjust the clock forward or backwards yourself. It is
possible to disable this particular feature, as described in the section ‘Changing the

Installer Parameters’ (page 15). You may also check the section ‘Configuration
& Service Data’ (page 26) to see how your Installer has configured your product.

What should I do if I get ‘lost’ while programming the ST9120C?

The LoT™ Display on ST9120C will provide you with help and tips to work through
the programming. Should you ever get ‘lost’, the simplest thing to do is to move the
slider to the RUN position, and then move it back to the appropriate programming
position where you got lost. At this point just follow the instructions again.

What happens if there is a power failure?

In the event of a mains power failure, the ST9120C display will go blank, the
indicator lamps will go out, and the control outputs will switch off. The real time
will be constantly maintained by means of the built-in battery backup, ready to
power back up as if nothing had happened when the mains power is restored. In
addition, all programmes and settings are stored in a special memory (called Non
Volatile memory) which requires no power to maintain information so will be retained
indefinitely.

Should the correct time and date ever be lost, for whatever reason, the message ‘SET
DATE + TIME’ will be displayed whilst the slider is in the RUN position. In this case,
simply follow the procedure described under ‘Step 1: Setting the Date & Time’
(page 6). It should not be necessary to make any changes to your programmes.

22

FAQ AND TROUBLESHOOTING

How reliable is 2-way RF communication?

The 2-way RF communication (also known as wireless communication) used by
Honeywell is extremely robust and reliable. When installed correctly the Signal
Strength test feature allows the Installer to locate the system components where
mutual signal reception is strong. During communication, signals are sent several
times to ensure receipt, and if any message is garbled, the error detection software
recognises this and ensures the message is repeated again.

What do I do if RF communication is lost?

Follow the steps in the Troubleshooting Guide on the next page. The most likely
cause for loss of communications is the CS92A batteries running low on power. This
will be indicated on CS92A, as described on page 19. Simply replace the batteries
(as shown on page 19) and wait a few minutes for communications to become re­established.

If this does not resolve the problem it may be that the RF signal path between
the ST9120C and the CS92A is blocked by a metal object. Check the direct path
between the two devices and reposition any object that may be blocking the signal,
or move the thermostat.

How do I know when to change the batteries in the CS92A
cylinder thermostat?

If the CS92A batteries need changing, ST9120C will show the message ‘SENSOR
LOW BATT’ and the tap symbol

will flash. . You can confirm this by pressing the
CS92A button, whereupon the red light will give a brief flash every second to indicate
a low batter y state. It is important to change the CS92A batteries as soon as the low
battery condition is indicated, as reduced battery power may affect the RF signal
strength and impair RF communications.

23

FAQ AND TROUBLESHOOTING

Troubleshooting Guide

This is a quick guide to help you diagnose and cope with possible problems with
your wireless control system. For further assistance, please contact your Installer.

Symptom Possible Cause Remedy

ST9120C has a blank
LCD display

No power to the
heating system

Check that there is power to the
heating system

Fault in ST9120C Call Installer

ST9120C indicates the
system is ON, but taps
are running with cold
water.

Temperature controls
are switched off or
set too low

Check that the temperature controls in
the system are set to appropriate levels

Boiler or other
system controls
have malfunctioned

Call Installer

ST9120C shows the
message:
‘INTERNAL FAULT’

Fault in ST9120C Call Installer

Every few seconds, the
ST9120C screen shows
the message:

ST9120C is counting
down the number of
days until your next
boiler service is due.

Arrange a boiler service before the
counter reaches zero.

After servicing your boiler, the Service
Engineer / Installer will reset the
ST9120C to remind you when the next
boiler service is due. Each service is
normally a maximum of 1 year apart.

Although the heating
is still operating, the
ST9120C screen keeps
flashing the message:

Your boiler service is
overdue.

Arrange an immediate boiler service.

After servicing your boiler, the Service
Engineer / Installer will reset the
ST9120C to remind you when the next
boiler service is due. Each service is
normally a maximum of 1 year apart.

The ST9120C screen
shows the message:

Your boiler service
is overdue and
the boiler has
been automatically
switched off to
ensure your safety.

Arrange an immediate boiler service.

If set to do so, it may be possible to
obtain limited use of the boiler by
pressing the EXTRA HOUR button.
Each button press will allow operation
of the boiler for 1 hour at a time, and
the screen will display the message
‘On 1h’.

After servicing your boiler, the Service
Engineer / Installer will reset the
ST9120C to remind you when the next
boiler service is due. Each service is
normally a maximum of 1 year apart.

24

Symptom Possible Cause Remedy

ST9120C shows the
message ‘SENSOR LOW
BATT’ and a flashing tap
symbol

CS92A batteries
are running low on
power

Change the CS92A batteries (see page
19 for how to do this)

CS92A battery low
indication (press CS92A
button and red light
gives a short flash every
second 0.1s on, 0.9s off.
Note: light will switch off
after approx 1 minute to
save battery power)

ST9120C shows the
message ‘NO SIGNAL’
and a flashing tap
symbol

CS92A batteries are
running low on power

Change the CS92A batteries (see page
19 for how to do this)

RF communication
path between
ST9120C and
CS92A is blocked,
possibly by a
metal object

Check direct path between both
products and re-position any objects
that may be blocking the signal

Relocate the CS92A transceiver, if
possible

ST9120C shows the
message ‘SENSOR
FAULT’ and a flashing
tap symbol

CS92A sensor error
indication (Press
CS92A button and red
light blinks 0.5s on,

0.5s off. Note - light will
switch off after approx
1 minute to save
battery power

CS92A sensor
cable may be
disconnected
from the wiring
terminals

Re-connect the sensor wires to the
CS92A terminals

Fault with CS92A Call Installer

Troubleshooting Guide (cont.)

FAQ AND TROUBLESHOOTING

25

26

50047645-002 A

CONFIGURATION & SERVICE DATA

Configuration Data (to be completed by Installer)

The tables below are for the Installer to complete to indicate how your ST9120C has
been configured.

Application

Insert application number as per Installation wiring diagrams:

Configurable Features Options Factory

setting

Installer configured
(tick box or note value)

ST9120C Configuration - standard

24hr or am/pm clock
display.

am/pm display
24hr display

Display backlight operation. Off

on if button pressed
on continuously

Automatic time change. disabled,

enabled

1-day or 5/2-day or 7-day
operation.

1-day operation
5/2-day operation
7-day operation

Number of ON/OFFs per
day.

2 on/offs per day,
3 on/offs per day

Default time programme. A = standard

b = at home

C = economy
Hot water set temperature From 40 to 85°C 60°C
Optimum start no optimum start

delayed start

optimum start on
Optimum start limit 1 hour

2 hours

3 hours
Optimum stop disabled

enabled
Frost protection temperature From 5 to 16°C 5°C
Minimum ON/OFF time 1, 2, 3, 4, 5 minutes 1 minute
Cycle rate 3, 6, 9, 12 cycles

per hour

6 cycles

Proportional band width From 1.5 to 3.0°C 1.5°C

Failsafe mode (loss of RF
communications)

off

on 20% *

* This option will not operate on a hot water only system