I cant follow this, maybe someone with a qualification can do the maths and
tell me if its right?

I put on one of the storage heaters last night ( not the new one, it hasnt
been fitted yet).

I have checked the meter daily so I know my electric usage each night is
between 15 and 17 units WITHOUT the storage heater(s) on.

I am charged at 5 p a unit ( kw?)

I put one 3.25 kw capacity storage heater on last night. The electric
meter read 82 units used overnight.

Now if I take away the 17 I would normally use during the night for my
essentials and drabs , that means the heater used 65 units over night.
That means the heater cost me nearly a fiver to have it on for one night.

Is my maths correct?

Is that right, should a 3.5 kw heater running for 7 hours on economy be
using that much electric?

Does that sound right to you? Just need to know. I am clueless and confused
totally.