Automating HVAC Fan with Fireplace Detection

Hey everyone, I’ve been trying to set up an automation in my smart home that turns on my HVAC fan whenever my fireplace is running. The idea is to improve air circulation, especially during colder months when the fireplace is used more frequently. I’ve been playing around with both Nest Manager and CoRE, but I’m hitting a snag when it comes to timing the fan off after 30 minutes.

Here’s what I’ve got so far: I’ve set up the automation to monitor the room temperature and outside temperature. If the room temp goes above 80°F and the outside temp drops below 40°F, the fan kicks on. That part works like a charm! But figuring out how to automatically turn it off after 30 minutes has been a bit of a puzzle. I can turn the fan on with those conditions, but I’m not sure how to implement the timer effectively without causing any conflicts or overlaps in the automation logic.

I’ve tried using delayed actions and even looked into creating custom routines, but nothing seems to stick. I’m wondering if there’s a more straightforward way to handle the timing aspect without overcomplicating the setup. Maybe I need to revisit the triggers or conditions I’ve set up?

If anyone has tackled a similar automation or has some tips on handling timed automations, I’d love to hear your thoughts! I’m really hoping to get this working smoothly so I don’t have to manually turn the fan off every time. Thanks in advance for any advice you can offer!