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Deleted member 54734
If the offpeak reading doesn't change, that just means the heaters were not on.
Could be a faulty meter, or just as likely blown fuses, the heaters were switched off, the heaters are broken, the consumer unit for the heaters is switched off, the timer is set to the wrong time, and so on.
I see your point, I hadn't thought of any of that.
On that setup ALL electricity will record on the night time rate not just the heaters.
Your night rate should advance even if your heaters are off.
If it doesn't it will be a timer issue and you'll need to contact your supplier.
My money is on a broken time clock as I don't know what time you took the pictures, but your time clock is saying 23:30 and looks like it hasn't the strength to get past the ON tag.