I purchased the Holmes Quartz mini heater, and enjoyed the first 4 days of its warmth, but on the fifth night the heater would turn on then shut off only 8 minutes after being on. I utilized the 4 hour shut-off feature since I didn't want to over heat it since it was my only source of warmth! nothing was inturrupting the beam, I eliminated all the other sensory items i had in my room (remote control) since it was said that remote sensors could confuse the heaters sensor. Let it cool down for a half hour then pressed the restart button on the back just like the manual said to do. The heater wouldn't stay on for more than 8 minutes at a time. Tried this 6 times, then decided it was getting too cold in my room and knew it was time for a return. I will say that this heater was silent like it was said to be, and I enjoyed the heat it provided to my bedroom when it was in working order. I wouldn't reccomend this heater for the fact that there isn't a heat-set temperature on it, it would turn on, heat up to it's potential then turn off when you wanted it to...usually... nor is there a fan to disperse the heat so the unit wouldnt over heat itself.