Can I use three core and earth for these stats of shall I buy three core heat resistant flex (without the earth).
For the cyl stat I would prefer to use heat resistant flex if it's available - which it is
from TLC. But it would be naughty not to have an earth in the flex, unless the cyl stat is double insulated, and it would be
very naughty to use the earth wire in the flex for any other purpose.