I read some posts saying it's not possible to convert a symbol to a float.
However I found out there is a way and it's not even complicated.
It took me hours though to try all the other ways that don't work.
So for anyone who is trying the same, here's how to do it:
1. put your symbol into [symbol2list]
(optionally using a known delimiting character)
2. use [unpack f]
(to select the first (or only) element)
use [unpack ? ? f ? ?]
(to select a special list element you want to extract)
3. continue to work with the f output of unpack which is a float now
(if you chose the right delimiting character and element for your input of course)