OP
davesparks
I would disconnect at the lamp end and run a length of t&e and connect the smoke n heat off its own supply as a temporary measure, this will prove you haven done owt silly and will show if the heat n smoke are compatible.
How do you think an incompatibility of the alarms going to cause the problem the OP has? I honestly cannot think of any logical way it could be causing this and am intrigued to know.