Hi Paul.
It depends...
I would suggest a smoke damper mounted in the ductwork connected to the fire alarm system might be one answer.
Other people might argue however that if you had a fire in the kitchen you would need to wait for the heat detector to activate before the damper closes, and by that time smoke could have already escaped through the ductwork onto the MOE.
Coversely you could also argue that evacuation wouldnt occur until the Heat Detector was activated to set off the fire alarm and that once the damper had activated any smoke that had managed to escape would have cleared by the time you wanted to use the MOE (especially care homes where that would be a last resort)
You need to establish what else is above the ductwork, are there windows nearby? Are those windows FR? If they do not need to be FR might they be left open?
Is it easier to move or route the ductwork to a more sensible location?
Would the layout of the care home mean that the external escape would be used early on in the evacuation?
Theyre all things to consider.
By far I think the easiest option would be to extend the ductwork and have it discharge in a more suitable location. I think you may find it cheaper too.
No doubt other members here will be able to offer better solutions for you , but thats what I have come up with off the top of my head!
