[quote author=sparxxxx link=1123961740/0#8 date=1124013067]Scruff warm air heating as i described is not environmentally unfriendly, nearly every modern office block in this country is heated by some sort of warm air system.
The system installed in the 60's and 70's were direct gas fired heat to air and were poorly designed, poorly constructed and very inefficient. [/quote]
Perhaps you know I've been in the industrial game for 45 + years Sparxxxxx.
You're comment about modern units are of course correct, and they have effective filters to prevent the spread of most bugs and germs.
The biggest single factor in the spread of legionelle is
the filters should be changed every 6 months, something that dosen't happen in real life.