It's hard to even imagine a radiator-based central heating system (whether gas- or home heating oil-fired) that doesn't have one of those cheap little bimetalli

It's hard to even imagine a radiator-based central heating system (whether gas- or home heating oil-fired) that doesn't have one of those cheap little bimetallic-strip thermostats, at least. Now lots of UK homes don't have per-radiator thermostats, or don't have central-heating timers: maybe that's what Nest meant to say.