by Mr White »
Fri Oct 27, 2017 8:07 pm
To avoid confusion I have to point out that what you have is a mains operated smoke alarm, it is NOT a fire alarm of any description. Fire alarms have to comply with a different set of regulations that smoke alarms do not comply to.
To answer your question.
There are many makes and options for mains smoke alarms. You have two different brands of smoke alarm. You should never mix brands of smoke alarm as they are often not compatible and could cause a fire if you try to connect them and one goes into alarm condition.
The best thing to do is to take back the new one and buy another of the same make as the ones you already have.
The bad news is if your existing ones are obsolete then you will have to change them all, which may not be a bad thing as the working life expectancy of smoke alarms (And smoke detectors) is 10 years.