Time was when you would only find a patio heater on the terrace of a trendy restaurant or bar. However, more and more patio heaters are showing up on backyard decks, patios and porches. There are reasons for this. Also called mushroom or umbrella heater, patio heaters radiate heat in circles ranging from 10' to 20' and increase outside temperatures by 10 to 25 degrees. Although not enough to transform the dead of winter into a balmy oasis, the difference is significant and will keep you outside longer enjoying the fresh air.