"Janet Baraclough" wrote in message

Double duvets are too bulky to fit in normal domestic sized
washers,
let alone tumblers.

True, but I've done it with a winter weight queen sized duvet. I just
had to be very careful about how long I let it run to stop
overheating. Short bursts only. With the duvet and all the tennis
balls inside, the poor old domestic drier was struggling but it still
managed well and has done so a number of times :-))