Scott
Regards
Hi,I am aware that smoke detectors should be replaced every ten years and it is my responsibly as a service engineer to inform my customers this needs to be done,however as you can imagine many customers do not take kindly and often use words like,well the last company never said that,so I wondered if it means there system does not conform if I recommend the detectors are in need of replacing as customer says no as at the end of the day it is my signature saying the system has been tested and is in good working order but as you can imagine I need to keep myself covered against any issues occurring should the customer have a fire?

I would obtain the recommendations of the manufacturer and show this to your client, if he/she refuses to take the advice, test the offending detector if it fails, replace it if it passes accept it, but ensure you endorse the logbook accordingly, similar what you would do for a variation. 

There is no requirement to replace detectors at 10 years in BS5839-1 - they merely must operate correctly and in a timely manner. 10 years is the length of some manufacturer's recommended service life and warranty.

There is a suggestion to change this at the next revision of the BS as part of UFS reduction, however currently as long as they work the service satisfies the standard.