Agree with TEAK36.........in our last house we had a new combi fitted in a bedroom.......perfectly safe.....only problem was the noise when it fired up.... and the fan ran on for a good while after the water was shut off.
It was convenient because of the short pipe runs to the taps but wouldn`t really want to do it again.
We still have a combi but miss not having an airing cupboard too......something else to consider.