Trigger: user departed and stays that way for 2 hours
Action: Flip virtual switch to on
For your first rule, the trigger becomes user arrives (only if virtual switch is on). The final action after turning on the heat is turning off the conditional virtual switch.
Now that I have had some sleep, I better understand this point. Depending on the rule to turn off the heat, @saurabh9 could probably combine @Sebastien’s actions to turn it back on.