We have 9 mains linked smoke alarms and 1 mains linked heat detector. I have replaced the battery on one of them which was 'wheeping'. Do I need to test each one separately or is pressing the button on one adequate? The combined noise is unbearable and doing it 10 times may cause a neighbour dispute!!

Hi, I can only answer for Kidde and Ei alarms. There you only press one of the buttons which will set off all the other alarms so you can check if they sound.