Had a worrying call from the agent who is looking after the rental of my flat. The carbon monoxide alarm went off yesterday, at that point the tenant called the agent who advised to open all windows etc. There has been an engineer out to the flat who has condemned the boiler, and has quoted to get the whole thing replaced. Although i have a valid CP12 certificate (issued 27/10/09) stating the device is safe to use, although there are a few NCS's, i was always planning on changing the boiler to a newer combi when i had the money available. My worry is that the tenant (5 month pregnant) and her partner have complained of side effects and are currently at the hospital getting checked out, i dont think i could have done anymore than what i have by getting the CP12 done and fitting a carbon monoxide alarm, but i'm really concerned it may have damaged the tenant, her partner or the unborn child. Hopefully the alarm and her quick actions have saved her them from permanent damage, but it really does highlight how dangerous not getting a properly functioning gas appliance can be, and even though i've done things, as far as i'm aware, by the book, it's really scared me to think it could have been so much more serious. I have told the agent to get the boiler replaced ASAP, although the tenant doesnt want anyone to access the flat whilst they are not in (still at hospital), so i cant get it done at the moment and am waiting contact back from agent. So if you are a landlord, and i know a few on here are, DO NOT take your Gas Safety lightly, make sure you have the correct alarms and make sure the CP12 is done every 12 months!!!!