Computherm Q3 User manual

COMPUTHERM Q3
digital room thermostat
Operating Instructions
You can watch the most important aspects of the usage of this thermostat on our video
presentation at www.computherm.info

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GENERAL DESCRIPTION OF THE THERMOSTAT
The COMPUTHERM Q3 type switched-mode room thermostat
is suitable to regulate the overwhelming majority of boilers and air
conditioners available in Hungary. It can be easily connected to any
gas boiler having a two-wire
thermostat connection point
and to any air conditioning
apparatus or electrical
apparatus, regardless of
whether they have a 24
V or 230 V control circuit.
Temperature can be
measured and set more
precisely as compared to 230 V AC
50 Hz

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simple, conventional thermostats. In heating mode, in accordance with
the selected switching sensitivity, the thermostat switches the boiler
or any other appliances on and o󰀨 below and above the adjusted
temperature, respectively, and contributes to reduce energy costs while
maintaining comfort. In cooling mode it switches the opposite way.
Temperature
Temperature
measurement unit
Room temperature
is displayed
Set temperature
is displayed
Sign of the boiler
working
Sign of the air
conditioner
working
The information shown on the liquid crystal display
of the thermostat includes the following:

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The simultaneous use of several COMPUTHERM room thermostats and
one COMPUTHERM Q4Z 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.
1. LOCATION OF THE DEVICE
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 protected from drought or extreme heat (e.g. direct sunlight,
refrigerator, chimney, etc). Do not use in wet, chemically aggressive
or dusty environment. Its optimal location is 0,75-1.5 m above oor
level.

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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
thermostatic head may disturb the temperature control of the at.
2. INSTALLATION 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 nor
the device to be controlled is connected
to the 230 V mains voltage. Modifying
the thermostat can cause electric shock
or product failure.

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• To install the thermostat, detach the rear panel of the thermostat
from the front panel by pressing the lock on the upper side of
the housing of the thermostat, as shown in the gure.
• With the help of the screws provided and some tools fasten
the rear panel of the device to the wall.
• Using a small screwdriver, remove the cover of
the terminal block from the inner side of the rear
panel. The thermostat controls the boiler or air
conditioner through a potential-free alternating
relay that has the following connection points:
1 (NO); 2 (COM) and 3 (NC). These connection
points are located under an inner cover on the
inner side of the rear panel.
• 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 relay. If you

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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, similarly as a switch would be connected.
• To prevent electric shock, replace the inner cover removed for the
connection of wires after the assembling process has been
completed.
ATTENTION! Always consider the loadability of the thermostat
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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3. PUTTING THE THERMOSTAT INTO OPERATION
The battery compartment is in the inner side of the front panel of the
housing. 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. Carbon-
zinc 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
measured room temperature. (If this information fails to appear on
the display, press “RESET” button located on the main panel of the
thermostat.

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4. BASIC SETTINGS
After removing the rear panel
of the device, the following
factory default settings can
be modied by relocating the
jumpers (black plugs) and/or
changing the position of the
orange-colored potentiometer
located on the main panel.
4.1 Selecting the Displayed Temperature
The temperature(s) to be shown on the display can be selected and
set by the left jumper.
With factory default settings the jumper is located on the central and
the uppermost pins, in which case the display shows the currently

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measured room temperature value, while the notice “ROOM”
appears in the bottom right corner of the display. In this case, the
adjusted temperature is visible only during the adjustment process,
for approximately 6 seconds after the last button has been pushed.
By relocating the plug onto the bottommost and central pins the
displayed temperature can be modied so that the display alternately
shows the current room temperature and the adjusted temperature
for 3-3 seconds, respectively. In this mode, the notices “ROOM”
and “SET” are alternately shown under the currently displayed
temperature in the bottom right corner of the display, indicating
whether the display shows the room temperature or the adjusted
temperature value.
4.2 Selecting the Switching Sensitivity (Accuracy)
The switching sensitivity of the thermostat can be selected by the
central jumper, which determines how much below/above the set

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temperature the thermostat switches on/o󰀨 the device connected to
it.
With factory default settings the jumper is located on the central and the
uppermost pins, resulting in a switching sensitivity of ±0.2 °C. It can be
modied to ±0.1 °C by relocating the jumper onto the bottommost and
central pins. A smaller switching sensitivity results in steadier room
temperature and therefore in higher comfort. The heat loss of the
room (building) does not depend on the switching sensitivity.
If higher comfort is needed, the switching sensitivity should be set
so that it provides a steadier room temperature. On the other hand,
please also take into account that the boiler should not switch on and
o󰀨 multiple times in an hour’s time except at low outside temperatures
(e.g. -10 °C), since the frequent on and o󰀨 switches of the boiler
reduce its e󰀩ciency and hence increases the gas consumption.
We recommend using the ±0.1 °C switching sensitivity for heating

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systems with high thermal inertia (e.g. underoor heating), and the
±0.2 °C switching sensitivity (factory default setting) for heating
systems with low thermal inertia (e.g. at panel radiators). You can
read more about switching sensitivity in Chapter 5.
4.3 Switching between the Heating and Cooling Mode
The heating or the cooling mode of the thermostat can be selected
by the right jumper. With factory default settings the jumper is
located on the central and the uppermost pins, which selects the
heating mode. By relocating the jumper onto the bottommost and
central pins, the cooling mode can be selected. The output terminals
1(NO) and 2(COM) of the thermostat are closed below the set
temperature in heating mode, and they are closed above the
set temperature in cooling mode (taking the switching sensitivity
into account).

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4.4 Calibration of the thermometer of the thermostat
You can calibrate the thermometer of the appliance (to correct
measured temperature). To this end all you have to do is change
the position of the orange-colored potentiometer by a Phillips
screwdriver. When you adjust the potentiometer clockwise then the
displayed temperature will be lower than that measured initially, and
when you adjust it anticlockwise the displayed temperature will be
higher than that. The displayed temperature can be adjusted within
a range of approx. ±4 °C.
Correction of the displayed temperature takes place a few seconds
after the adjustment.
ATTENTION! If the modication of the basic settings was done
after inserting the batteries and the modications did not take eect,
please press the “RESET” button located on the main panel of the
thermostat.

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5. OPERATION OF THE INSTALLED THERMOSTAT
The thermostat controls the device connected to it (e.g. gas boiler or
pump) based on the temperature measured by it and the currently
set temperature, taking into account the switching sensitivity of
the thermostat (factory default ±0.2 °C). This means that if the
thermostat is set to heating mode and 22 °C, then with a switching
sensitivity of ±0.2 °C the connection points 1(NO) and 2(COM) of
the output relay are closed below 21.8 °C (heating is turned on) and
opened at temperatures above 22.2 °C (heating is turned o󰀨). In
cooling mode, the relay switches exactly the opposite way.
The closed status of the output relay terminals 1(NO) and 2(COM)
is indicated by the “HEAT” or “A/C” icon in the lower left corner of
the display, depending on the selected operating mode.

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Below the temperature adjustment buttons
(and )a switch is located. For both
the economy () and the comfort (☼) positions
of the switch a di󰀨erent temperature can be set
between 5 °C and 40 °C, in steps of 0.5 °C. After
setting the economy and comfort temperatures, the temperature
desired at the moment can be selected using the switch.
5.1 Economy Mode ( ) (left hand position of the switch)
In the left hand position of the switch, the thermostat provides
the set economy temperature (e.g. night temperature) to be
maintained at the place where the thermostat has been installed.
5.2 Comfort Mode (☼) (right hand position of the switch)
In the right hand position of the switch, the thermostat provides

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the set comfort temperature (e.g. daytime temperature) to be
maintained at the place where the thermostat has been installed.
6. SETTING THE DESIRED TEMPERATURE
After putting the thermostat into operation and adjusting the basic
settings the thermostat is ready for operation and the adjustment of
the temperature can be started.
For energy e󰀩ciency it is recommended that the comfort temperature
is only used those times, when the room or building is in use,
because every 1 °C decrease of temperature saves approximately
6% energy during a heating season.
The factory default temperature is 18 °C for the economy (w ) position
and 20 °C for the comfort (☼) position. These default temperatures
can be changed as follows:

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• Move the switch according to the temperature you would like to
change (economy (w ) or comfort (☼)).
• Press the or button, after which the notice “ROOM”
disappears, the notice “SET” (adjusted value) appears in the
bottom right corner of the display. Meanwhile, the temperature
value shown on the display switches from room temperature
to the default temperature (18.0 °C/20.0 °C) or to the last set
temperature (this temperature is blinking on the display). By
pressing the buttons repeatedly or continuously (the change in
values is accelerated), the desired temperature to be maintained
at the place where the thermostat has been installed can be set in
steps of 0.5 °C.
• Approximately 6 seconds after setting the room temperature to be
maintained, the device automatically switches to normal mode.
The notice “SET” disappears from the bottom right corner of the

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display, and once again the current room temperature and the
notice “ROOM” are displayed.
• The previously set temperature can be freely changed any
time using the and buttons. Always the last set
temperatures are in e󰀨ect.
7. BATTERY REPLACEMENT
The average lifetime of the batteries is 1 year. The icon
alternately replacing the temperature value on the display indicates
low battery voltage. Replace the batteries whenever the icon
indicating low battery voltage appears on the display (see Chapter 3).
After battery replacement, the desired temperature should be
adjusted again, because during the battery replacement the
thermostat is reset to factory default settings.

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Warning! Alkaline batteries may only be used for this appliance.
Carbon-zinc 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.

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FREQUENTLY ASKED QUESTIONS
When you think that your appliance is operating incorrectly or
encounter any problem while the appliance is being used then
we recommend that you read Frequently Asked Questions (FAQ)
available on our website, where we collected the problems and
questions that most frequently occur while our appliances are
being used, along with the solutions thereto:
http://www.computherm.info/en/faq
The vast majority of the problems encountered can be solved
easily by using the hints available on our website, without seeking