A few weeks ago, I wrote about mains steam delivery to buildings - with the benefit that an office or apartment building can obviate the need for the maintenance and space devoured by large boilers. Well, here is a familiar sight you’ll see on the streets of New York - a donkey boiler. When a building’s heating system conks out and needs a major overhaul or replacement, a container with wobbly chimneys and tottering connection to the building’s central pipework, is parked outside, often for weeks at a time, providing the heating and hot water that residents demand. New Yorkers are used to central services such as heat in the winter and air conditioning in the summer. The donkey boilers ensure the appetite for heat or cold air is sated at all times as essential repairs are undertaken.