I would recommend purchasing the optional fog machine timer. However, there should be a website listed somewhere to contact for missing parts.
The unit hold about 1 quart and that will last about 2 hours of continual use.
It will automatically run continuously. This is it will run and then heat up again and run every 50 seconds. You do not have to trigger it as it will do this itself. You can also do this manually if you want to just fog at certain times.