(What time is it?)
Wann findet der Vortrag statt?
(When is the presentation going to take place?)
(Do you know what time it is?)
Können Sie mir sagen, wann der Vortrag stattfindet?
(Can you tell me when the presentation is going to take place?)
Indirect yes/no-questions take "ob" ( = if, whether) as a subordinating conjunction.
(Will the heat pump be installed tomorrow?)
(Can you tell me whether the heat pump will be installed tomorrow?)