To turn the fire place on, press two buttons on the remote control at the same time; the "off" button and the large flame button. After this you will see flames appear. 

It will take about 10 minutes to fully heat up the fire place. After that you can regulate the temperature and the flames.
The condensation will disappear after a few minutes. 

To turn the fire place off, press the "off" button once. 

Keep in mind that when you use the gas fireplace, this will quickly heat the living room. This causes the floor heating to switch off, which means the bedrooms and bathroom will no longer be heated.