Well the heater leaks current and a class A gfci won't even hold if the heater is large enough. Class b GF protection does not protect life so how can it work for life protection except that class b can be used where class a is not available? Actually look at rule 68-068 especially subrule 7 So if the heater is within 3 meters and not the other side of a wall then yes GFCI protection is required. If the heater is further than 3 meters then no.