Don’t know if I’m posting in the right place
We installed like for like sized DImplex Quantum heaters on E10 2 years ago.
It turns out they were well oversized because they retain heat better than storage heaters plus E10 spreads the charging more evenly.
They worked so well we had the added ‘on peak’ heating element disabled to ensure all heat used was only stored heat. Again we found the quantum held the heat all day.
Then this year we’ve replaced old storage heaters in another house but this time we replaced with half the size of the originals! We used the logic it charges 3 times a day rather than once. I’m aware it can’t fully charge from empty in less than 5 hours officially but it doesn’t seem to need to unless it’s very cold. Turns out they all operated just fine during the very cold weather we got!
So now we have twice the space and amazingly controllable heaters.
So going for E10 instead of E7 and making the saving on the cost of larger heaters is well worth it!
Next up I’m installing an electric car charger so you have 3 opportunities to charge at ‘off peak’ rates instead of 1 so the cheaper and smaller than I would like battery will suit my needs fine
Hope the above is useful info