BRK COMBOS HELP!

[Ms.electricity]

Licensed electrician in Massachusetts. I have a 9unit building that we’re replacing devices throughout the units and common spaces. 120v system all hardwired interconnecting w/back up 10yr battery photoelectric. BRK has a 18 device max. With 12 max smoke detectors.
I have 17 in total.
(9) heats
(6) smokes
(2) Smoke/CO
Going through testing every single heat and smokes signaling the whole system. When I’m testing the Smoke/CO they will not signal the system. I’ve swapped them out TWICE the smoke/COs to new ones. For shits I threw two heat detectors in replace and everything is talking. As soon as I put the combos on the problem continues. Has anyone had this problem?!?!
-Voltage is 120.1
-No continuity between all conductors
-All on the same circuit
-Run must be less than 1000ft no way it’s that long here.
-Swapped Sqaure combos with round maybe it’s the model? NOPE still happening
Like I said when the combos are removed everything communicates
I’m at a lost!! Called BRK and they can’t tell me anything why it would happen
Has anyone experienced this???

 

[tthh]

Strange...I've used the combos a lot and I always check each detector one by one. Always worked.

EDIT: I've used SC7010B which take batteries and are not lifetime battery ones.

 

[ramsy]

when the combos are removed everything communicates

Someone has a Samsung Inverter-run refrigerator on the same line.

 

[Ms.electricity]

Strange...I've used the combos a lot and I always check each detector one by one. Always worked.

EDIT: I've used SC7010B which take batteries and are not lifetime battery ones.

Yeah those are a lot better than the Sqaure ones they are junk. And I know I’m really scratching my head on this, it doesn’t make any sense. I’ve used BRK for a long time and had nothing like this happen to me before.

 

[ptonsparky]

Have you tried the 1-888-WTF-HELP number yet?

 

[Ms.electricity]

Have you tried the 1-888-WTF-HELP number yet?

Haha I’ll give them a call!