Economy 7 or not?

I have a Pulsacoil 2000, and I'm currently seeing if I can bring our electricity bills down

We are not currently on Economy 7, and I've a feeling we'd be better off if we were.

I'm just trying to work out how much a Pulsacoil 2000 costs each day, we have hours time to come on between 4am and 8am, and then we use the boost button for an hour in the afternoon....I've worked out that on a our standard rate traffic (16.05p/kw) that's probably about £75 a month, does that sound about right (and does it sound like we're using it the right way?)

My wife is actually at home during the day, so we do have the heating on in the day when it gets cold in the winter (not storage heaters, electric panel heaters), but I still have a feeling we'll save more by suing the Pulsacoil to heat up in the night on an economy 7 tariff

Any advice would be grand!