The council have recently fitted hard wired smoke alarms with battery back up in my flat, no idea of the make as I cant reach them to see. Over the past couple of weeks since theyve been installed I have heard a one off beep around 3am in the mornings, being a small flat Ive no idea what one beeped.  Last week I was woken up by a one off very loud beep from the alarm in my bedroom and again this morning around the same time. The one off beep seems to be going from one alarm to another, not all on the same night though. I searched the internet and found that if the tempature lowers at night it can set off a beep on said alarm. I dont like heat in the bedroom in the winter months so does this mean the alarm will go off every night!!! I have reported the problem to the council but like all councils they dont rush to do repairs. 

Is there any solution to this problem? tia

Trying to detect a false alarm is extremely difficult and the first port of call is to determine if it is a faulty unit by replacing the unit also checking the electrical wiring. Therefore I would suggest you contact the council, bager them if necessary, to have it replaced and the wiring checked.

As a safety consideration you could purchase a grade F2 detector (battery only) fixing it with double sided sticky tape, until your system is repaired, or contact the local Fire Service to see if they can help.

Check out https://www.firesafe.org.uk/uk-fire-rescue-services-details/.