It should never be hot. The thermal fuse should not be hot. Something is wrong with your module.
With module mounted inside wall (in in-wall can, below wall switch) it works fine about 10 meters from gateway.
Currently I have 5 modules working well for 6 months.
The only one problem I have is with poor quality Hongfa mini relays - some of these sometimes get sticky contacts and I need to remove wall switch and knock into relay. I changed relay to NPA-AS5 and problem gone.
I do not know how to advice you.
I suspect that there is some problem with your module - first try check why it is hot?
Or you live in very noise environment.