velleman K2649 Thermostat with LCD Display Instruction Manual
- June 12, 2024
- Velleman
Table of Contents
velleman K2649 Thermostat with LCD Display
Product Information:
Product Name: Thermostat with LCD Display
Model: K2649 Manufacturer:
Velleman NV Features
- Very precise digital display of set and actual temperature
- Connecting capability for an ‘economy switch’ to decrease the set temperature
- Wide setting range for hysteresis and desired temperature
- Can be used for regulating room temperature and other applications
Specifications
Power supply and transformer included –
Mains voltage: 220/240V (110V for USA and Canada)
Relay output: 240V, 3A max –
Dimensions: 123.5x62x65 mm
Product Usage Instructions
Assembly: – Ensure you have the right tools, including a basic multi-meter if
required. – Carefully solder the components to the PCB surface, making sure
the solder joints are cone-shaped and shiny. – Trim excess leads as close as
possible to the solder joint. – Always check the value of the components on
the parts list and remove them from the tape one at a time. 2. Construction: –
Power Supply Mode ‘P2649V’: – Diode: Watch the polarity. – Zenerdiode: Watch
the polarity. – Diodes: Watch the polarity. – Resistors: Mount and solder
according to the values listed on the parts list. – IC socket: Watch the
position of the notch. – Ceramic capacitor: Mount C3 with a value of 100nF
(104). – Transistor: Mount T1 with model BC557B. – Terminal blocks: Mount J1,
J4, and J2 according to the instructions provided. – Vertical trimmer: Mount
RV5 with a value of 4M7 (5M). – Horizontal trimmer: Mount RV4 with a value of
10K. – Electrolytic capacitor: Watch the polarity when mounting. Note: Always
refer to the assembly hints and construction
instructions provided in the manual for a successful project.
Digital readout of both set and actual temperature.
Specifications
- Adjustable hysteresis: 0,2°C (0,4°F) to 10°C (18°F).
- Resolution of the display : 0,1°C or 1°F.
- Mains voltage : 110/230VAC
- Relay output : 240V, 3A max.
VELLEMAN NV Legen Heirweg 33 9890 Gavere Belgium Europe
www.velleman.be
www.velleman-kit.com
The very precise digital display of both the set and actual temperature makes
this thermostat very easy to use.
Also very useful is the connecting capability for an ‘economy switch’: when
the contact is closed then the set temperature is decreased by a number of
degrees.
No measuring apparatus is needed for adjustments. Thanks to the wide setting
range of both the hysteresis and the desired temperature, this kit can also be
used for a lot more applications than only regulating room temperature.
Features
- Wide measuring and regulating range: -50 to +150°C (-60 to +300°).
- Adjustable hysteresis: 0,2°C (0,4°F) to 10°C (18°F).
- Resolution of the display: 0,1°C or 1°F.
- Can be set for degrees Celsius or Fahrenheit.
- Connecting capability for economy switch.
Specifications:
- Power supply and transformer included.
- Mains voltage: 220/240V (110 for USA and Canada).
- Relay output: 240V, 3A max.
- Dimensions: 123.5x62x65 mm.
Assembly hints
Assembly (Skipping this can lead to troubles ! )
Ok, so we have your attention. These hints will help you to make this project
successful. Read them carefully.
Make sure you have the right tools
- A good quality soldering iron (25-40W) with a small tip.
- Wipe it often on a wet sponge or cloth, to keep it clean; then apply solder to the tip, to give it a wet look. This is called ‘thinning’ and will protect the tip, and enables you to make good connections. When solder rolls off the tip, it needs cleaning.
- Thin raisin-core solder. Do not use any flux or grease.
- A diagonal cutter to trim excess wires. To avoid injury when cutting excess leads, hold the lead so they cannot fly towards the eyes.
- Needle nose pliers, for bending leads, or to hold components in place.
- Small blade and Phillips screwdrivers. A basic range is fine.
For some projects, a basic multi-meter is required, or might be handy
Assembly Hints
- Make sure the skill level matches your experience, to avoid disappointments.
- Follow the instructions carefully. Read and understand the entire step before you perform each operation.
- Perform the assembly in the correct order as stated in this manual
- Position all parts on the PCB (Printed Circuit Board) as shown on the drawings.
- Values on the circuit diagram are subject to changes.
- Values in this assembly guide are correct*
- Use the checkboxes to mark your progress.
- Please read the included information on safety and customer service
- Typographical inaccuracies excluded. Always look for possible last-minute manual updates, indicated as ‘NOTE’ on a separate leaflet.
Soldering Hints
- Mount the component against the PCB surface and carefully solder the leads
- Make sure the solder joints are cone-shaped and shiny
- Trim excess leads as close as possible to the solder joint
DO NOT BLINDLY FOLLOW THE ORDER OF THE COMPONENTS ONTO THE TAPE. ALWAYS CHECK
THEIR VALUE ON THE PARTS LIST!
REMOVE THEM FROM THE TAPE ONE AT A TIME !
Construction
POWER SUPPLY MODE ‘P2649V’
B. DISPLAY MODULE ‘P2649D’
Pa y attention to the position : the upper surface must be at 8mm (0,3 inch) above the pcb surface (see drawing 2.0).
You may put some pieces of paper between the LCD and the pcb, to help you holding the display on the right height.
- First solder only the pins at the four corners.
- Verify the height, and correct if necessary.
- Then solder the remaining pins.
Be very careful, for this part is not cheap!
Sensor
Calibration is performed by alternately adjusting the meter at the freezing
respectively boiling-point of water. Therefore the sensor first has to be
prepared.
DON’T shorten the connection wires of the sensor, unless you are not going to
fit it directly onto the pcb in the future.
Solder two isolated wires (75 cm or 30“) to the sensor (see fig. 3.0)
Make use of a cable of the desired length (max 10m, and preferably screened to avoid interferences) if you are not going to fit the sensor onto the pcb in the future.
Make the connections waterproof with heat-shrinkable tubing :
- Cut off a piece of shrinking tube with a lenght equal to 5cm.
- Slide the shrinking tube over the wires and over the sensor (Fig. 4.0).
- Heat the shrinking tube using a hair dryer or, better still, using a paint stripper.
Take care that everything is well covered.
Connect the whole to the place marked with ‘R32 SENSOR’. The connection order
is unimportant, unless with screened cable: the screen then comes on the side
marked with ‘SENSOR’. Connect a mains cable to the screw connector J1-MAINS.
Flat cable
Attention: The connecting order (whit regard to the pcb-edge) must be the same as on the power supply module (see fig. 5.0).
Adjustment
During assembly you already made your choice for degrees Celsius or degrees
Fahrenheit version. The adjusting method is the same for both, only the values
on the display are different. The figures for Fahrenheit are mentioned within
brackets.
The first adjustment is done at the freezing-point.
-
Fill a beaker with ice cubes and plunge the sensor into the melting-water (Fig. 6.0). As long as not all the ice is molten, the temperature of the melting water is kept at 0°C (32°F), and after a few minutes the sensor will be at 0°C too.
-
Then adjust with RV2 until the display reads 00.0 (32°F).
-
After zero-adjustment, the sensitivity of the meter has to be adjusted.
-
Plunge the sensor into boiling water, but see to it that the sensor does not come too close to the bottom or wall of the kettle.
-
After a few minutes, the sensor temperature has risen to 100°C (212°F).
-
Then adjust with RV3 until the display reads 100.0 (212°F).
-
Now let it cool down for about half an hour, and do the complete adjustment over again once more.
-
Remark : when the sensor has to be replaced for any reason, then you have to readjust completely!
Use
The set temperature is displayed when you push the button S1.
You can change it by gradually turning potentiometer RV1 until the display
shows the desired temperature. With the standard values for R2 and R33 (91K
resp. 22K), the adjusting range is about 5 to 30°C (40 to 85°F).
You can change this range by using other values for R2 and R33 :
| Range | R2 | R3 |
|---|
-50°C (-60°F) to 0°C (32°F)
+50°C (120°F) to 100°C (212°F)
+100°C (212°F) to 150°C (300°F)
| 51K
33K
33K
| 7K5
12K
16K
? You can also experiment yourself in order to obtain an optimum adjusting range for your application.
-
Solder a 1M trimmer parallel to both R2 and R33 (see fig. 7.0).
-
Adjust both trimmers so that you obtain the optimum range.
-
Afterward, replace the trimmers by normal resistors which approximate the set value as close as possible.
-
You can lower the set temperature by a number of degrees (preset with RV5), e.g. by night or during your absence, by connecting a switch or a relay contact (e.g. a timer such like K2603 or K1682) at the place marked with ‘E.S.’ (Economy Switch).
-
The hysteresis is the difference between the temperatures at which the output is switched on resp. switched off. Depending on the application, a smaller or larger hysteresis may be desired: to regulate the room tem-perature for instance, a small hysteresis is desirable. On the contrary, this makes no sense with water heaters, so, in this case, you should select a larger hysteresis.
-
You can adjust the hysteresis with RV4.
-
The adjusting range is about 0,2 to 2°C (0,4 to 4°F) when R24 and R25 are 180K resistors, and 1 to 10°C (2 to 18°F) when you fitted wire links.
-
The setting of the hysteresis does not depend on the set temperature. Do not set the minimum hysteresis right from the beginning: in this case the regulation is most precise, however it could happen that the heating gets switched on and off much too fast and too often (e.g. when the thermostat is located near the radiator). This is not too healthy for the heating installation and/or relay, and too much energy is consumed. Therefore start with RV4 in the middle position, and then search the ideal position for your application.
Suppressing inductive loads :
Should the operation of the thermostat get disturbed by the switching of
inductive loads (even if the switched power is not so high), then this is due
to the sparks produced in the relay. In most cases this can be reme-died by
putting a VDR (e.g. VDR300) over the contacts. Moreover a series connection of
a 100 ohm resistor with a 47 or 100nF/400V capacitor can be placed in parallel
with the VDR in order to further reduce the sparks (see Fig. 8.0).
Mounting
- Spacers & screws are not included.
The rectangular opening in the power supply module is used as a passage for the wiring to the mains input, the relay output and the E.S. (Economy Switch), see fig. 10
The display module can be mounted above the power supply module using spacers (See fig. 11).
- This thermostat exactly fits into the box type B2649.
- In case you use this box, you can fit the sensor onto the pcb in such a way that it passes through the opening in the side of the bottom. In this way, the sensor reacts more quickly and accurately upon the room temperature, and it doesn’t get influenced by the heat-dissipation of the transformer and such-like.
- In case of panel mounting, you may use a somewhat longer flat cable, so you can simply mount the pcb’s with their solder sides towards each other, and the connections are easily accessible.
- You also could use screw connectors for the sensor connection. Wherever and for whatever application the thermostat may be used, always take into account that the mounting of the sensor determines the quality of the regulation: the quicker it reacts upon the changing temperature, the better.
- In case of liquids, this is not such a problem: you can attach the sensor on the outside of the metal pipe or boiler (you could use a little bit of heat-conducting paste), or make the sensor waterproof and plunge it into the liquid.
- Air however is a much worse heat-conductor, so that the body of the sensor does not heat up/cool down that quickly. This can be improved by circulating the air around the sensor.
- Especially in large rooms, which are heated by means of hot air, it can be interesting to place the sensor in the (cold) air circulation, for instance nearby the air inlet of the convector.
- The intake air (which has the actual room temperature) then makes the sensor warm up quickly as the room temperature increases.
PCB
PCB layout (Display module)
layout (power module)
Diagram
Modifications and typographical errors reserved – © Velleman nv. H2649IP – 2004 – ED1 (rev1.0)
References
Read User Manual Online (PDF format)
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