> ...that is always on

with predictable results w.r.t. quality-of-living when your house already has central heating.

Agas used to be a very rural middle-class thing: it was how I imagine most countryside homes' heating and cooking worked, and it scaled from a modestly-sized cosy cottage to being in expansive stately homes. But postwar, and especially since the 1960s, Agas are just a status-symbol appliance to me.

Like, in North America, you know you've made it when you have a Wolf range and a Subzero fridge in your kitchen. In the UK, it's when you've got an Aga.

...probably because the only comfortable way to run the thing is by also having central air-conditioning installed and running full-blast while you use the thing.