Briza Infrared Patio Heater

I had great expectations for this style heater. I have a small unheated garage and three seasons of the year I am able to use it as a makeshift exercise room. Winters are tough, though. I live in Southern New England so from December to around the beginning of April the garage can be so cold it makes it uncomfortable to use for an hour-long exercise session. I was hoping this heater would remedy that by heating the garage to at least 55-60F, a temperature that is comfortable when the body is moving and circulation enhanced. I've used it on cold days six times trying to problem-solve a solution that would help raise the ambient temperature. The best I can get is five degrees more, something that is unacceptable when the temperature in the garage starts at 40F. First I tried the highest setting, L3 for two hours. The thermometer hardly budged more than 2 degrees. Next, I raised the tripod setting to its highest and pointed the face of the heater down. Same result. Then I decided to preheat the garage for two hours before using it. Same result. I went back and re-read the instructions thinking I might be missing something and also checked a few YouTube to see if they provided any insight. The only thing I could find different was understanding that the radiant heat has to heat objects in a room and those objects, in turn, heat the air. So I lowered the tripod settings as far down as it would go and pointed the heater at the cement floor hoping it would absorb heat and then that would rise inside the garage. I turned it on and left it for 4 hours. When I came back the heat had risen only 5 degrees, still inadequate to heat the garage to a comfortable 55-60F. The best I can determine is this heater works only in very small enclosed spaces and when pointed at the user, warms him/her with radiant heat, but if they move from a direct line of sight it suddenly goes cold. So if you are reading a book or tying flies at a bench, this would be great, but then why would I do those things in an unheated garage [rhetorical, the answer is self-evident]. Frankly, I am greatly disappointed.