Does this mean I won’t be able to move tariff once the smart meter is installed?
I’m afraid the answer to that is it depends who you ask. With the smart meter you will get, it ought to be possible. Sadly, though, just because it’s possible it doesn’t mean that they will do it.
… they will fit a timer so that I can boost heating with convection heaters on the off peak rate or boost the hot water?
… all our heating, hot water, and electric shower operate on the off peak rate at any time of day. … will they only run at cheap rate during the economy 10 hours.
The new system isn’t at all like your THTC arrangement. One big difference is that all usage in offpeak periods is charged at the offpeak rate, regardless of whether it’s for heating or hoovering. There are two timers involved; one of them determines whether current usage is recorded on the peak meter register or the offpeak one. The other switches power to a dedicated heating circuit on and off, usually at the same times as the first one.
How do my quantum storage heaters know when the cheap rate is?
It depends on the type of heater, but in any case they will only normally get power for charging during the offpeak periods. They will be turned on and off by the second time switch I mentioned above.
Many storage heaters and water immersion heaters have two feeds: one on the dedicated offpeak circuit (the switched circuit) and the other on the ‘domestic’ 24-hour circuit (the constant circuit). Some storage heaters use this circuit out of offpeak hours to keep its own controls running, and to make it possible to boost the heater’s output by operating as an ordinary fan heater. This will be charged at peak rates except during offpeak periods. For water heating, the constant feed makes it possible to boost the water temperature if somebody used all the hot water. Again, if you use the boost function outside of offpeak periods, it will be charged at peak rates.
You should find that the Economy 10 tariff doesn’t cost you much more or less than your current arrangement, but you’ll have to do your sums. I hope you’ve been told what the available tariff rates are.