Dog flap advice please! Questions

I have a lovely 5 month old Cavalier King Charles spaniel and I encourage him to go outside when he wakes etc so most wees and poos are outside and he’ll take himself out as I always leave the back door open. Trouble is, it’s getting very cold leaving the back door open. He’ll sit by the door, but doesn’t bark so I don’t know he wants it open. Has anyone had any success with dog flaps or training barking? Many thanks Debbie

I'm sorry, I have no experience of dog flaps, I have always worried about security and draughts! What about hanging training bells from the door handle? If you hang them low enough, your puppy will ring them accidentally at first, but I always found Cavaliers very quick to housetrain so I'm sure he would catch on quickly. Google, Dog Training Bells, and see what you think.