So how much am I actually saving by having my heating on for 3 hours less a day?

[furrycat]

We have a pretty standard terrace house, 10 radiators approximately. And a new, economical boiler.

Am I shivering in vain for the sake of about 30p?

No idea. But I wonder if the extra 'work' the boiler must do to warm up a much colder house cancels out (or negates) the savings made by having the system off for a few hours.

I tend to turn the heating down (but not off) when I'm out/asleep, instead of turning it off completely.

Maybe someone more knowledgeable will come along with the answer....

do you have access to your meter? take a gas reading for a day at 3 hours less and one at 3 hours more and work it out per your bill?

would be interested in what you find esp if are you with british gas?