Advice on your thermostat's connection
A boiler works on grid power. So does a thermostat. A thermostat receives its power from the boiler. In the Netherlands, thermostats are always powered by 24 volts. In Belgium, that's 230 volts in most cases. Pay careful attention to this, then, when purchasing a (new) thermostat, because when you connect a 24-volt thermostat to a 230-volt clam, the thermostat will burn immediately and be broken.
Do the check
Your thermostat is connected to your boiler with thermostat wires. In order to ensure that the thermostat receives the right number of volts, the thermostat wires need to be connected to the right clamp on the boiler. To make sure your thermostat wires have been connected correctly, go through the following steps:
Check the thermostat wires in your boiler
Step 1: Unplug the boiler from the socket.
Step 2: Grab the boiler manual. If you can't find it, search for it online.
Step 3: Open the boiler and look for the clamps. They look like a row of screw terminals, each with its own number.
Step 4: Once you've found the clamps, check to see if the thermostat wires are connected properly. In the boiler manual, you'll find exactly what each number (above the clamp) stands for.
The thermostat wires will usually be thin and colored blue and/or red. If you notice that, according to the thermostat manual, the wires haven't been connected to the right clamps, you can simply move them to the right clamp (using a screwdriver).
Step 5: Once you're certain that the thermostat wires have been connected to the right clamp, you're done. Close the boiler and plug it back into the socket.
Step 6: Before testing if the thermostat is working, it's important to reset the boiler. You'll read exactly how to do that in your boiler's manual.
Connecting your thermostat step by step
Step 1: Switch off the AC power by converting the ground fault circuit in your fuse box.
Step 2: Connect the thermostat to the power cables that come out of the wall at the location your previous thermostat was installed. In the manual of your thermostat, you'll find exactly how to connect these cables.
Step 3: Click the screen on the thermostat. The screen fits on the part you installed on the wall in only 1 way. Most thermostats will produce a 'click'.
Step 4: Switch the AC power on again.
Step 5: Did you install a smart thermostat? Use the app to complete the installation. In the app you indicate which WiFi network your thermostat is connected to.