When I entered 21 in the system it says 21:CC+Com A/T. I also have some installation notes left by the Alarm company (PFS). It says Zone 1 (Front door) 2.3 ohm, zone 2 (Lounge) 1.8 ohm, zone 3 (Kitchen) 1.9 ohm, zone 4 (Rear Garden door) 1.9 ohm, zone 5 (Dining room) 1.7 ohm, zone 6 (1st Floor...