Hi @Perran83
This is the right spot to ask questions about Heimdall. 
Adding fire alarm functionality to Heimdall has been discussed on the old forum, I am not really sure how I can improve on a flow that responds on smoke/fire sensor and take an action like send messages and sound a sirene.
All functionality that Heimdall offers over building an alarm with regular flows have to do with the fact that Heimdall simplifies the arming with delays, pre-arming check, Partially arming, Full arming etc.
For a fire alarm all these extra’s don’t apply, it just has to function always.
Maybe you can tell me how you’d like to see it integrated? Maybe you can convince me to add it anyway because I’m overlooking something 
