thisisthecount
DIY
I'm about to order this wired smoke alarm system as it can network but I just went to see how my existing fire alarms are hooked up and there appear to be three wires? What/how would I connect the new one when it arrives? This old one isn't linked tot eh other one on the landing as I know for sure it only goes off downstairs.
This is the old one:
This is the old one: