The Mr. Heater Propane Garage Heater is a very safe model
There are actually specially-made heaters for areas like garages and warehouses. Here's an example: http://www.lennox.com/products/garage-heaters/
See: How Safe are Vent Less Heaters
There are many different brands of portable heaters that can be used in a garage workshop. Some popular and reliable brands include Convair and Sylvain.
My new house as electric baseboard heaters. Are they safe for pets and babies?
Sometimes. Oil-filled space heaters, which are fire-safe are preferable. Regular electrical space heaters can be used if they are placed in safe places, and turned off before leaving work.
Yes, propane heaters are safe if you follow a few precautions. www.propanefl.com/safety_tips.htm gives a comprehensive list of safety tips.
24"
Yes, kerosene heaters are safe for indoor use, such as the Mr. Heater F215100 Portable Buddy Series, which is certified for indoor operation.
DeLonghi heaters are safe to keep in home. This brand of home heaters has a automatic shut off. If this heater brand tips over or becomes over heated it is made to shut off on it's own.
Portable heaters are safe to use in the manner written on the heaters instructions. Some portable heaters are meant for use outdoors only, so using those heaters indoors would not be safe. The other thing to consider with heater safety is do you have children who might accidentally touch the heater, if you do you need to make sure that your heater does not heat up enough to burn the child. Also, its important to make sure that your house's electrical system is properly grounded so that your portable heater, if it is electrical, does not short out.
18 inches above the garage slab
As safe as they are installed against any surface. If installed corrected they are very safe.