Thanks for the replies, i know it was not ideal using 2x pirs in series. But I can free up a zone (Window contacts) and connect PIR in that room in series with the window contact, therefore ie zone 4 PIR+ window contact . That would allow the entry/exit zones to have their individual PIR (Timed). I was more concerned about the loop resistance. All loops then would be in the 20-22 Ohm range, except for door entry