- as I said, they get used only a small number of times per year (often at Christmas). Of course, the real killer for the stored hot water approach arises when (usually at Christmas) one or two of those around decide to have (generously full) baths!
That reminds me of Christmases a few years ago, when my family all went "up North" to stay with the wife's sister.
She had an oil-fired Aga that did the cooking, and fuelled the CH and hot water.
Baths were forbidden on Christmas Day, otherwise the turkey was still raw at 5pm!