Existing building and fire alarm. Call it system "A". An addition is put on the the building. There are no firewalls and both the old and new sections are 1 building. The FA designer not realizing this, specified a separate FA system for the addition. Call this system "B". System "A" and system "B" are different vendors. The FA contractor has proposed tying the systems together using supervised relay circuits so that alarms, troubles, etc will pass both ways to act as one system. The original system "A" will be the one with the central station communicator.
We have already discovered in testing that there is 1 issue that will have to be addressed, but I'm not sure if it is worth discussing at this point if this whole arrangement can't be done in a compliant manner.
I'm wonder if this can be done in a manner that complies with NFPA 72?
