Are Ventless Heaters Safe?
The answer to, "Are ventless heaters safe?" is yes and no. If it's an electric heater, it doesn't require a vent, so it's always safe from any fumes even in a closed area. A ventless garage gas heater might be another question.
If you are going to use a patio heater, you are free to choose any style or model you want since you are outside. When it comes to the garage be sure to be smart about your decisions.
If you are going to use a ventless gas garage heater, you might want to rethink that option. While ventless gas garage heaters do exist, they aren't really the safest. If you are going to spend time in the garage or shop, it's best to go with a propane or gas heater that is properly vented.
Many are trying to not use a vent to avoid the trouble of making sure everything is properly vented. In that case the electric garage or shop heater is the best choice.
Are ventless heaters safe? Yes, when you use electric. Obviously it would be best to read the directions and specifications of any model that you choose.
Related: Garage Heaters