Computherm Q20 User manual

COMPUTHERM Q20
Programmable, digital room thermostat
Operating Instructions

TABLE OF CONTENTS
1. A general description of the thermostat 4
2. Important warnings and safety recommendations 6
3. Information appearing on the display of the thermostat 7
4. Location of the thermostat 8
5. Putting the thermostat into operation, basic settings 8
5.1. Connection of the thermostat 8
5.2. Commissioning the thermostat 11
6. Operation of the thermostat that has been put into operation 13
7. Settings 17
7.1. Selecting the operating mode (FUNC) 17
 7.2. Switchingonando󰀨oftheprogrammedmode(PROGRAM)  17
 7.3. Selectingswitchingsensitivity(HYSTER) 18
 7.4. Calibrationofthetemperaturesensor(TCALIB) 19
 7.5. Calibrationofthehumiditysensor(HCALIB) 19
 7.6. Settingthehumiditylimitforcooling(HLIMIT) 19
 7.7. Switchingonando󰀨ofthepumpprotectingfunction(PUMP) 20
 7.8. Restoringfactorydefaultsetting(RESET) 20

8. Operating modes of the device 21
8.1. Economy mode ( ) 22
8.2. Comfort mode ( ) 22
 8.3. Manualmode( ) 23
 8.4. Programmedmode( )23
  8.4.1.Adescriptionofprogramming 23
8.4.2. Steps of programming the device 27
8.4.3.Theuseof“COPY”function(copyingtheprogramofadaytoanotherdayorotherdays) 30
  8.4.4.Modifyingtheprogramsofthedevice 32
  8.4.5.Programinspection 33
8.5. Temporary manual mode until the next program switching 34
 8.6. Temporarymanualmodefor1to99hours(partyprogram) 35
 8.7. Temporarymanualmodefor1to99days(holidayprogram) 36
9. Operation of backlight 38
10. Locking the control buttons 38
11. Battery replacement 39
12. Technical data 42

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A GENERAL DESCRIPTION OF THE THERMOSTAT
The COMPUTHERM Q20 type switch mode room thermostat is suitable
for regulating a large majority of boilers, air conditioners, humidiers and
dehumidiers in circulation. It can easily be connected to any gas boiler,
air conditioner, humidier and dehumidier with two-wire room thermostat
connection point and to other electrical devices, regardless of whether the
device has a 24 V or 230 V control circuit.
230 V AC
50 Hz
Thermostat Boiler

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The device can be programmed as needed so that the heating/cooling or
humidier/dehumidier system heats/cools and humidies/dehumidies
your apartment or o󰀩ce to the desired temperature or humidity at the times
you want, and it contributes to the reduction of energy costs in addition to
providing comfort. Separate independent daily programs can be created
for each day of the week. For each day, beside 1 xed switching time
(PROG ) 10 freely adjustable (in 10 minutes increments) switching times
(PROG – PROG ) can be set, and a di󰀨erent temperature (in 0.5 °C
increments) and humidity (in 1 percent increments) can be assigned to
every switching times.
The simultaneous use of several COMPUTHERM room thermostats and one
COMPUTHERM Q4Z or Q10Z zone controller provides the possibility for the
thermostats to also control a pump or a zone valve in addition to starting the
heater or cooler. This way it is easy to divide a heating / cooling system into
zones, thanks to which the heating / cooling of each room can be controlled
separately, thus greatly increasing comfort. Furthermore, the zoning of the
heating / cooling system will greatly contribute to the reduction of energy costs,
as due to this only those rooms will be heated / cooled at any time where it is
required.

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2. IMPORTANT WARNINGS AND SAFETY
RECOMMENDATIONS
• Before starting to use the device, please study carefully the instructions for
use and follow strictly the instructions therein.
• The thermostat is designed for business or household (non-industrial)
use, it can be used to control any electrical device, the power of which
does not exceed 1.84 kW (load capacity: max. 30 V DC / 250 V AC; 8 A
[2 A inductive load]).
• This device is designed for indoor use. Do not use in wet, chemically
aggressive or dusty environments.
• The manufacturer will assume no responsibility for any possible direct or
indirect damages or income losses incurring during the use of the device
• The device does not work without power, but the thermostat can remem-
ber the settings. In the event of a possible power supply failure (power
cut/battery replacement), it can continue to operate without any external
intervention after the power supply is restored
• Before starting the actual control of the device connected to the
thermostat, make sure that the device works perfectly and can be-
operated reliably even when controlled by the thermostat.

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Figure 1
3. INFORMATION APPEARING ON THE DISPLAY
OF THE THERMOSTAT
Programming button
Current/left time
Programmed mode icon
Current program
Mode button
Menu button
Manual/temporary
manual mode icon
Icon indicating that the
party/holiday program is
switched on
Economy mode icon
Icon showing that
cooling is switched on
Icon showing that
heating is switched on Comfort mode icon
Room temperature
Battery charge level
indicator icon
Key lock button
Icon showing that the key lock is
switched on
Up/Down button
Measured humidity
Set temperature/humidity
Current day Icons showing that the humi-
ding/dehumiding is switched on

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4. LOCATION OF THE THERMOSTAT
It is reasonable to locate it in a room used regularly or for many hours per
day so that it is in the direction of natural ventilation in the room but protec-
ted from drought or extreme heat (e.g. direct sunlight, refrigerator, chimney,
etc). Its optimal location is 0.75 - 1.5 m above oor level.
IMPORTANT WARNING! If the radiator valves in your at are equipped
with a thermostatic head, adjust it to maximum temperature or replace the
thermostatic head of the radiator valve with a manual control knob in the
room where the room thermostat is to be located, otherwise the thermos-
tatic head may disturb the temperature control of the at.
5. PUTTING THE THERMOSTAT INTO OPERATION,
BASIC SETTINGS
5.1. Connection of the thermostat
WARNING! The device must be installed and connected by a qualied
professional.Beforeinstalling,makesurethatthatneitherthethermostat
orthedevicetobecontrolledisconnectedtothe230Vmainsvoltage.

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Modifyingthethermostatcancauseelectricshockorproductfailure.
Pressing the lock on the upper side of the housing of the thermostat, remo-
ve the back cover of the thermostat as shown in the gure
Fix the back of the device to the wall using the included screws and some
tools.
Remove the serial terminal cover from
the inside of the back panel using a small
screwdriver.
The receiver unit controls the boiler or
air conditioner through a potentialfree
alternating relay whose connection points
are: 1(NO), 2(COM) and 3 (NC). These
connection points are located on the inside
of the back panel, under an inner cover.
Connect the two connection points of the heating or cooling equipment to be
controlled to the normally open 1(NO) and 2(COM) terminals of the

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relay. If you would like to operate an old boiler or any other
device that has no connection points for thermostats, then
the 1(NO) and 2(COM) connection points of the thermostat
should be connected to the mains cable of the device, simi-
larly as a switch would be connected.
To avoid electric shocks, replace the inner cover
removed to connect the wires after installation.
ATTENTION! Always consider the loadability of the receiver
unit and follow the manufacturer’s instructions of the heating
or cooling equipment. The device must be installed and connected by a
qualied professional! The voltage appearing at terminals 1 (NO) and 2(COM)
depends only on the system being controlled, therefore the dimensions of the
wire are determined by the type of the device to be controlled. The length of
the wire is of no signicance.

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5.2. Commissioning the thermostat
The battery compartment is in the inner side of the front panel of the hou-
sing. Insert 2 AA alkaline batteries (LR6 type) in accordance with the
diagram in the battery compartment.
Warning! Alkalinebatteriesmayonlybeused for this appliance. Car-
bonzinc batteries known as durable or long life batteries and chargeable
accumulators are not suitable for the operation of this appliance. Icon
appearing on the display to indicate low battery voltage warns reliably that
the batteries should be replaced only when alkaline batteries are used.
After the batteries have been inserted, the display ashes the day, time,
program number, adjusted and measured temperatures, measured humi-
dity level and icons showing the operating mode and battery power level.
After inserting the batteries, snap the front panel of the device into the rear
panel and touch the button. After touching the button, the display
stops ashing, the thermostat goes to the main screen and the setting
process can be started.

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6. OPERATION OF THE THERMOSTAT THAT HAS BEEN
PUT INTO OPERATION
The thermostat controls (manually or via programming) the devices (e.g.
gas boiler, pump or dehumidier) connected thereto on the basis of the
humidity/temperature measured by it and being set, considering the switching
sensitivity of the thermostat (±0.2 °C/±1.0% according to factory default) This
means that when the thermostat is set to heating mode and 22 °C then at
switching sensitivity of ±0.2 °C the connection points of the output relay of the
receiver unit 1(NO) and 2 (COM) close at a temperature below 21.8 °C (the
heating system switches on), and open at a temperature above 22.2 °C (the
heating system switches o󰀨). In cooling mode the relay switches conversely.
When the thermostat is set to humidifying mode and to 60%, then at switching
sensitivity of ±1.0% the output relay of the receiver unit 1(NO) and 2(COM)
close at a relative humidity below 49% (the humidier switches on) and open
at a relative humidity above 51% (the humidier switches o󰀨). In dehumidifying
mode the relay switches conversely.
The closed state of the connection points 1(NO) and 2(COM) of the output
relay is indicated by the , , or icons appearing on the display of the
device, according to the selected mode.

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7. SETTINGS
ATTENTION! According to factory default setting the key lock of the thermostat
automatically switches on after 30 seconds which is indicated by the icon
that appears in the bottom right corner of the display. To unlock the keyboard,
touch the button for 2 seconds until the icon disappears from the display.
The thermostat allows a number of setting options by which the operation of
the thermostat can be tailored to your liking. You can enter the setting menu of
the thermostat by pressing the button for 2 seconds. Then the continuously
illuminated time and the ashing English abbreviation of the relevant day
(Monday: MON; Tuesday: TUE; Wednesday: WED and so on) appear on the
screen. In the setting menu you can modify the current setting with buttons
and and touching the button you can move to the next setting.
The currently modiable setting is ashing on the display. After the current day
and exact time have been set, you can perform additional settings as follows:

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Displayed
abbreviation Descriptionofthesetting Setting options Factory default
setting
Detailed
description
FUNC Operating mode
HEA: heating
HEA Chapter 7.1.
COO: cooling
HUM: humidifying
DEH: dehumidifying
PROGRAM Switching on and o󰀨
of programmed mode
OFF: Switched o󰀨. In this case the
thermostat is working in a manually set
Economy mode or comfort mode. ON Chapter 7.2.
ON: Switched on. In this case the thermostat
is working according to a pre-set program or
manual mode.
T UNIT Temperature unit °C °C --
°F
HYSTER Switching sensitivity
±0.1 – ±1.0 °C ±0.2 °C
Chapter 7.3.±0.2 – ±2.0 °F ±0.4 °F
±1 – ±5% RH ±1% RH
MIN Minimum adjustable temperature/
humidity
5 – 45 °C 5 °C
-- 41 – 97 °F 41 °F
0 – 98% RH 30% RH
MAX Maximum adjustable temperature/
humidity
5 – 45 °C 35 °C
--41 – 97 °F 95 °F
1 – 99% RH 80% RH

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Displayed
abbreviation Descriptionofthesetting Setting options Factory default
setting
Detailed
description
T CALIB Calibration of the temperature sensor
-3.0 – +3.0 °C 0.0 °C
Chapter 7.4.
-6.0 – +6.0 °F 0.0 °F
H CALIB Calibration of the humidity sensor -10 – +10% RH 0% RH Chapter 7.5.
H LIMIT Setting humidity limit
in case of cooling
OFF: function switched o󰀨
80% RH Chapter 7.6
30-99: if the measured humidity is higher
than the set value then the cooling system
switches o󰀨
A LIGHT Automatic backlight
OFF: switched o󰀨
ON --
ON: switched on (backlight switches on for 10
seconds after any button has been pressed)
BRIGHT Backlight brightness 0 - 10 7 --
B LIGHT Backlight of the buttons
OFF: switched o󰀨
ON --
ON: switched on (backlight of the keys
switches on and o󰀨 simultaneously with the
backlight of the display)

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Displayed
abbreviation Descriptionofthesetting Setting options Factory default
setting
Detailed
description
B SOUND Acoustic signal when buttons are
touched
OFF: switched o󰀨
OFF --
ON: switched on
LOCK Automatic key lock
OFF: automatic key lock is switched o󰀨
ON --
ON: automatic key lock is switched on
(the key lock is activated 30 seconds after
touching the last button)
PUMP Switching on and o󰀨 of the pump
protection function
OFF: switched o󰀨 OFF Chapter 7.7.
ON: switched on
RESET Restoring factory default settings
--: saving the settings and
exiting the settings menu after touching
the button -- Chapter 7.8.
RES: restoring factory default setting after
touching button
To exit the setting menu and save the settings:
- touch the button, or
- wait for 30 seconds until the display of the thermostat is reset to the default
screen, or
- go through the settings with the button.

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7.1. Selecting the operating mode (FUNC)
You can easily switch between heating (HEA; factory default setting),
cooling (COO), humidifying (HUM) and dehumidifying (DEH) modes. The
connection points of the output relay of the receiver unit 1(NO) and 2
(COM) close at temperatures below those set in the heating mode, at
temperatures above those set in the cooling mode, below the humidity
level set in the humidifying mode and above the humidity level set in
the dehumidifying mode (taking the switching sensitivities into account).
7.2.Switchingonando󰀨oftheprogrammedmode(PROGRAM)
The thermostat can be used in both programmed and non-programmed
modes. When the programmed mode is on, in automatic (programmed)
mode the thermostat controls the devices connected thereto according to
the pre-set program, but it can be switched to manual mode by touching the
button, and in this case it will constantly control the devices according to
the temperature/humidity set manually, regardless of the pre-set program.
When you switch o󰀨 the programmed mode, you can set two independent
temperatures/humidity levels (comfort and economy), and you can easily

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switch between the two modes by touching the button. In this case the
devices connected to the thermostat cannot be controlled according to the
pre-set program.
7.3.Selectingswitchingsensitivity(HYSTER)
The switching sensitivity can be adjusted. By modifying this value, you can
dene the di󰀨erence below/above the set temperature/humidity where the
thermostat should switch on/o󰀨 the device connected thereto. The smaller
this value, the more stable is the inner temperature/humidity in the room and
the comfort improves. Switching sensitivity does not a󰀨ect the heat loss of
the room (building) and vapour formation.
When higher comfort level is needed, it is reasonable to select the switching
sensitivity so that it ensures as stable inner temperature/humidity as possible.
On the other hand, two frequent starts and stops of the controlled device
should be avoided because this may reduce the e󰀩ciency and lifetime of
the device.
The switching sensitivity can be set in the temperature range of ±0.1 °C to
±1.0 °C / ±0.2 to ±2.0 °F and in the humidity range of ±1 to ±5% RH. Apart from
some special cases, we propose to use ±0.1 °C or ±0.2 °C (factory default)

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when a heating/cooling system should be controlled. For humidication/
dehumidication we recommend you use a switching sensitivity of ±1%
(factory default) or ±2%. For more information about switching sensitivity
please refer to Chapter 6.
7.4.Calibrationofthetemperaturesensor(TCALIB)
The accuracy of the thermometer of the thermostat is ±0,5 °C. The temperature
displayed by the thermostat can be modied by maximum ±3.0 °C / ±6,0
°F compared to the temperature measured by the temperature sensor, in
increments of ±3.0 °C / ±6.0 °F or 0.1 °C / 0.1 °F.
7.5.Calibrationofthehumiditysensor(HCALIB)
The accuracy of the humidity sensor of the thermostat is ±3% RH.
The relative humidity displayed by the thermostat can be modied by
maximum ±10% compared to the humidity measured by the sensor,
in increments of 1%.
7.6.Settingthehumiditylimitforcooling(HLIMIT)
When a cooling system including surface cooling is controlled, it is important
that the air in the room must not reach dew point because in this case
condensation occurs which can cause serious damages. Using this function,

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you can set the humidity level above which the thermostat will stop cooling to
prevent condensation.
7.7.Switchingonando󰀨ofthepumpprotectingfunction(PUMP)
In order to prevent the pump from jamming, the activated pump protection
function will start the devices connected thereto for 1 minute every day at 12:00
p.m. (noon), if switching was not done either on the respective day or on the
previous day (e.g. during non-heating period). The pump protectionfunction
only works when the controlled device is in operable condition.
7.8.Restoringfactorydefaultsetting(RESET)
This function resets all settings of the thermostat to factory default. To
restore factory default setting choose option “RES” at “RESET” function in
the setting menu and move on with the button.
Leaving the “RESET” function in default state ( ) after touching the
button the thermostat saves the settings, exits this menu, and after returning
to the home screen continues its operation according to the operating mode
set beforehand.