Louise Campos wrote:
My Dad is installing a Danfoss RMT 240 volt room thermostat to control
a Danfoss HS3-3 point mid-position motorized valve. Would 3 core and
earth 1mm cable have sufficient current carrying capacity for this
application?

Thank you for your help.

Yup, it'll be more than enough. It's physical robustness is more significant
than its current-carrying capacity in this context.

Rick