Hot and cold in Tewkesbury Abbet

 Tewkesbury Abbey is heated by two amazing boilers. Each is surrounded by fins to increase the surface area because they give off infra-red thermal radiation. As such they are painted matt black to be the best emitters.

I also found this max-min thermometer. It's so old that it is marked in Fahrenheit only. It looks like a proper mercury thermometer. It doesn't look to have been reset for a long time. Translated into Celsius, the minimum is about 6 Celsius and the maximum 20 Celsius. That's a bigger range than perhaps I expected. The thermometer is on the opposite side of the nave to the heaters so there must have been a period of sustained hot weather.