~~~~~~ My updated review, written 3 days after receiving a replacement unit promptly from Amazon: ~~~~~~ This review now has a star rating of 3 stars, replacing my earlier star rating of 1 star. The 3-star rating is the average of my original 1 star review and my updated review, in which the replacement heater earned 5 stars. You will see more details about the reason for the change in star rating in my update below. First, let me tell you up front that I am a big fan of the Mr. Heater Buddy heaters. I have owned an MH9BX model since early 2013, and have used it regularly for heating in my meditation dome for 9 months each year, and it has always worked great, and it continues to work great even now, more than 5 years later. In fact, I left a glowing 5-star review for the MH9BX here on Amazon a few years ago. As I have related in the text of my original review (to be found below this section), I ordered a Big Buddy MH18B/BRV from Amazon in late October. The heater arrived here within 2 days, but unfortunately (as related in great detail in the earlier section of my review, shown below), the heater turned out to be defective when I fired it up. Being a scientist and an engineer, and being a bit stubborn, I subjected the heater to a five more test runss before deciding that it was indeed defective. I then notified Amazon of that fact and returned the defective heater, and perhaps because it was a Prime item and I am an Amazon Prime member, Amazon managed to get a new replacement unit to me by noontime the next day (amazing job, Amazon, thank you!)! I have now been using the replacement MH18B/BRV heater for 3 days in my meditation dome, and I can report that it works perfectly; it seems to be just as well-behaved, stable, reliable and robust as my older Buddy MH9BX heater. I have used it both without the internal electric fan (which is the most common mode of operation for me), and with it, and it works fine in both modes. One final note before closing this update section: Please note that WHENEVER I operate a propane heater anywhere indoors, including using the Mr. Heater Buddy and Big Buddy heaters in my meditation dome, I always have installed and operating, on a nearby wall, a battery-operated carbon monoxide detector with an alarm and digital readout. I consider this essential. BTW, in all of my 5.5 years of operating my older Mr. Heater Buddy heater model MH9BX in my meditation dome, I have NEVER seen the digital readout on the carbon monoxide detector budge above zero (0.0)! ~~~~~~~~~~~~ My original 1-star review for the original defective heater ~~~~~~~~~~~~ First, let me tell you up front that I am a big fan of the Mr. Heater Buddy heaters. I have owned an MH9BX model since early 2013, and have used it regularly for heating in my meditation dome for 9 months each year, and it has always worked great, and it continues to work great even now, more than 5 years later. In fact, I left a glowing 5-star review for the MH9BX here on Amazon a few years ago. Recently, I decided to sideline the MH9BX and to replace it with the larger Big Buddy MH18BRV model, which, on the maximum heat setting, can produce 18,000 BTU of heat, twice the amount of heat that the smaller MH9BX model can produce, simply so that when I walk uphill the the meditation dome at 3 AM on really cold mornings, it would hopefully raise the interior temperatures from below freezing to 72 degrees F much more rapidly. So, I ordered the MH18BRV here on Amazon a few days ago, and it arrived here on Oct. 27. I immediately unpacked the unit, read the instruction manual, and installed it, using the same 20 lb. propane tank fuel hose (Mr. Heater Hose Assembly #F273702) and fuel filter (Mr. Heater Fuel Filter #F273699; and yes, I replace the fuel filter periodically)) that I have always used with my older MH9BX unit, which has always worked perfectly. Then, as soon as the sun went down and night came on, I tested the unit. It worked great for the first few minutes, with the sole exception that there was a significantly greater quantity of blue flames extending beyond the perimeter of the ceramic heater tiles than the manufacturer's user manual says is acceptable and safe, and there was also a somewhat worrisome blue flame peeking out and leaking out at times from behind the left side (as viewed from the front) and top corner of the metal frame of the left-side burner tile, but I assumed that the slight to modest amount of flame-over (aka over-flame) was merely a temporary artifact of the initial break-in process, and that these unwanted extraneous flames around the edges of the tiles would disappear as time passed. Well, after about 4 minutes of operation at the 9,000 BTU heat level setting (this uses the left tile only), I increased the power level to the highest heat setting of 18,000 BTU (and yes, the control knob was in the full detent position each time). After about 6 minutes (total runtime by now had been 9 to 10 minutes since start) at the high heat setting, the quantity of flames extending well beyond the edges of the two heater tiles grew quite significant, and there were also bluish flames appearing from behind the metal frame of the heater tiles, particularly toward the top of the left tile, and then in short order I started to hear a burbling sound and a frequent loud popping sound (that is, minor explosions) as unburned gas leaked out from behind the tiles around the edges and then ignited violently (aka "exploded"). I immediately approached the unit, being careful to stay far from the flames that were now extending well beyond the tiles and out of the front and top of the grill, and squatting well to the side of the unit for safety reasons, turned off the control knob. Phew! That had been a bit scary! I then, over the next 24 hours, tried firing up the heater three more times, each time with a cool-down period of at least 3 hours between tests, but each time, after about 6 to 10 minutes of operation at the high power (18,000 BTU) setting, the quantity and size of the flames leaking beyond the edges of the tiles grew excessive, and then, if I allowed the unit to remain on even longer, the fireworks grow worse and worse over the next 2 minutes, until I was forced to turn off the unit. BTW, I also performed some test runs in which I tried to operate the unit only at the 4,000 or 9,000 BTU settings (these settings use the left burner tile (as viewed from the front) only), but the same problems as noted above always occurred after about 5 to 10 minutes of runtime, and in each case, the fireworks (flames where there should not have been flames) and attendant explosive popping sounds grew so violent that I was forced to turn the unit off. I wish to stress, once again, that these tests were conducted using the same Mr. Heater fuel hose and Mr. Heater fuel filter (and yes, I have occasionally replaced the fuel filter over time) and 20 gallon propane tank that I have successfully used for years to supply propane gas to my older MH9BX heater, which has always worked flawlessly. Incidentally, all tests except for the final test were run using the hose/fuel filter from the 20 gal. propane tank attached to the propane inlet port located directly under the red control (on/off/heat level) knob switch, and with nothing at all attached to the propane inlet port on the other side of the unit. Then, for the final test run -- since some Amazon reviewers for this product had stated that when operating the unit on a hose from a 20 lb propane tank, it was important to hook up a 1 lb. propane tank to the other propane inlet port in order to block it; that is, to keep it from leaking propane -- I hooked up a 1 lb. propane tank to the unused propane inlet port, just to see if this might perhaps help to improve the so-far rather disappointing and fiery performance of the device, but this special runtime condition did not help to improve matters at all. (BTW, I eventually checked with the man
