these - would be good for a large open space but expensive. but cheap to run
https://www.heat-outdoors.co.uk/sho...-636014.html?gclid=CJ6Ixdzy2coCFUqeGwodAecM6A
My neighbour has something similar and does not rate it all, says you dont know it is on unless you stand right in front of it.
big ££££and u need a gas supplyWhat about the type of heater you see in wickes.. The overhead gas fired tube type. Might be suitable for the workshop as it has a flue, so no fumes to worry about.