Check the back hook of the ceiling heater you are using at home now,does it have short and horizonal slide? This is not safe, picture as below showes you why its risky.
We know all houses may shake sometimes, maybe caused by trains, trucks, or very small earthquake etc, though all these shake is very slight and people can not feel it, but the nail in the hook will get moving, of course this moving is very very slight as well, but day by day, month by month, one day finally the nail gets out of the hook slide, and the ceiling panel heater fall down.
The heater hook at your home maybe not same as the one in above picture, but as long as it has short slide or the slide is not beveled, this will be a timebomb!
Hook others using
Hook we are using, long and beveled slide, nails will never fall off, very safe.