In article ,
"TheScullster" writes:
What cable is required between these linked smoke and heat detectors, other
than power supply?

Mains smoke detectors normally use triple and earth including the
power supply, i.e. one additional signal wire interlinks them all.
Not looked at a mains interconnected heat detector, but I guess it
must be the same in order to link with smokes. AFAIK, there's no
standard for the signalling, so you must use all the same make of
detectors. You might want to buy them all at once, in case they go
obsolete half way through your refurb.

--
Andrew Gabriel