I was around 15 ft away and this lil heater was keeping me warm. I used this heater and a 800 watt comfort zone halogen infrared heater at opposite ends of a 13x45 ft room with 7 ft ceiling while outside it was in high 30s. Indoor thermometer stayed around 67/73 degrees.

works great

As a purely radiant heater, which pushes no warm air, it is very effective at keeping a single person, or perhaps 2 if they can both be in the radiance cone, warm in a chilly environment. It is like standing by a fireplace, with radiant energy warming only what is in its cone. It might heat a small room, but it would take a long time. But if you are working in a cold garage or garden shed, point this at yourself and turn it to high. It is very comfortable. This is the third similar device that I have purchased over the years. The first (different brand) is still excellent after several years, but a bit noisy. I used it while building a small boat in my garage and allowed me to work for long hours. The second, yet another brand, was very noisy and jerky while oscillating, and seemed ready to break at any moment. I returned it. The Joy Pebble is quiet and oscillates smoothly. The other units did not have the timer feature. I do like this. If I leave the area where it is working, the unit will turn itself off after a chosen time period. This is really a good idea.
It is very lightweight, which is not very reassuring, but it made it unscathed through the USPS system, which says something during the Christmas rush. There are two things that would improve the item: First, the up/down angle range of adjustment is very narrow. I would like to place this it where I need it to radiate horizontally, but it won't go quite that low. Second, and more important, I would prefer the two heat settings to be higher. High, at 800 watts, is good but 1000 would be better, when I need to be further away from the heater. The 400 watt low setting is not useful for my purposes. 600 would be a better low power level for me.

heats quickly, great for the pool house

Think of it like an infrared heat lamp. Works best when you are fairly stationary (workbench, desk, recliner, etc.) because it heats out to around 3 feet. The rest of the house can be too cool but you'll be warm with this thing pointed at you. Placement is important. I don't like it in front of me watching TV because it glows fairly bright (red). It works great under my desk pointed towards me on low. With it to the side, it only warms that one side. I'm thinking about getting another one so I can have one on each side. Then I'll be like a slice of bread in a toaster. I think they could easily make these with fan blades to push the hot air.

I tested wattage and low = 340 watts / high = 845 watts. Fairly efficient compared to small ceramic electric heaters that can go up to 1500 watts.