Friday, August 20, 2021

The Realist: Mr. Heater Big Buddy Radiant Heater

This is a guest post from The Realist. He sends:

The Big Buddy heater in operation, supplied by a 
common 20-pound propane tank.

Disclaimer: All products mentioned in this review were purchased by myself. I did not receive samples, evaluation models, or other compensation from any manufacturer or retailer. I have no formal relationship with any manufacturer or retailer mentioned in this review - I have only been an arms-length customer. All brand names and product names used in this review are the trade names, service marks, trademarks, or registered trademarks of their respective owners. Further, this review reflects my unique circumstances and subjective opinions with regard to performance and other characteristics of the products being reviewed. Your mileage may vary.

    February 15, 2021 my home in the Dallas-Fort Worth area lost power for twenty-eight hours during the two coldest days in several decades. I described my experience in the article "The Realist: The Texas 2021 Winter Storm" ( One of the lessons from that event was that I needed a heat source that could keep the central portion of my house warm during similar conditions in the future.

    As soon as the power came back on, I started looking for emergency heating solutions for my home. I talked with friends and coworkers, watched YouTube videos, and did a lot of online research. Two heating options presented themselves: a kerosene heater or a propane heater.

    Many people I talked to recommended kerosene heaters, and I have used a small one in the past. Other people I talked to recommended propane heaters.

    Based on my past personal experience, I was less than satisfied with kerosene heaters. Replacement wicks were hard to find at the time. Kerosene was and is hard to find in my area. And, even though my kerosene heater burned with a nice blue flame, it emitted an odor that my family did not like. So, I decided against a kerosene heater.

    I have also had experience with small propane heaters, and have been happy with their performance. Propane heaters emit very little odor. And, propane is readily available.

    I looked at propane heaters that attached to the top of 20-pound propane cylinders and heaters that sat on the floor and got their propane from a cylinder through a hose. I eventually settled on the Mr. Heater Big Buddy radiant heater, model MH18B (, after seeing it used in several videos by Canadian YouTuber Steve Wallis (

    After deciding on the Big Buddy heater, it took several months to find one in stock for less than scalper prices. I was finally able to purchase one mid-July.

Mr. Heater Big Buddy MH18B

    The box the Big Buddy heater came in plainly states it is "indoor safe." The Big Buddy heater can produce 4000, 9000, or 18,000 BTU per hour. It can operate from either a large propane cylinder, or one or two one-pound disposable cylinders. Heat is produced from one or two ceramic "tile" burners on the front of the heater. In the center below and in front of the tile burners is the pilot light assembly, which incorporates the gas jet, igniter, and thermocouple.

    On each side of the heater, behind doors, are two propane regulators where one-pound cylinders can be screwed on. The regulators swivel to make screwing on the cylinders easier. On the left side, there is also a quick-disconnect fitting. When using the one-pound cylinders, the doors can be closed over the cylinders.

    On the right side near the top is the control knob for igniting the pilot light and selecting the amount of heat. Pushing down on the knob and rotating it counterclockwise to the pilot light position will trigger a spark to ignite the pilot light, and turning it further counterclockwise will ignite one or both burner tiles.

    Older models of the Big Buddy heater had a small battery powered fan, but the fan was deleted a year or two ago to avoid import tariffs. My heater does not have the fan. Fan assemblies are available as a replacement part, but I have not yet decided if I want to add a fan.

The supply hose, with filter, connected to the left
propane tank connection.

    To use the Big Buddy heater with a larger propane cylinder, a hose is required and a fuel filter may be required. Some of the Mr. Heater hoses and after-market hoses can exude oils from the hose material when attached to the high pressure propane cylinder, and those oils can clog the gas jets in the heater.

    The Mr. Heater documentation is full of warnings about dangers of improper use of the heater, and how to use the heater. However, the documentation is not very clear about which accessories are required to use the heater with a large propane cylinder.

    I ultimately purchased the F273704 10-foot Buddy Series Hose Assembly ( and the F273699 fuel filter ( While the fuel filter is not required with this particular hose, I felt having it might protect the heater if there were contaminates in the propane or foreign matter got into the hose during storage. (I did not purchase the Mr. Heater F271803 quick disconnect hose (, which can also be used to connect to a
large propane tank. The fuel filter cannot be used with this hose.)

    Some users recommended that a carbon monoxide detector be used when operating this heater in an enclosed space. I have not yet purchased a carbon monoxide detector.


    Be sure to leave plenty of open space around and above the heater. The manufacturer recommends a minimum of six inches on each side, twenty-four inches in front, and thirty inches above the heater. Based on my testing of the heater, I would recommend at least a foot on each side, and several feet above and in front of the heater - it produces a lot of heat on the high setting. When operating the heater, periodically check nearby surfaces to make sure they are not getting unreasonably warm. Also make sure there is adequate ventilation to avoid low oxygen conditions and avoid carbon monoxide risks.

    When used with a large propane tank, optionally screw the fuel filter into the propane tank connection heater. (I decided to use the left connector since that is the side where the quick disconnect fitting is located, but there is nothing in the owner's manual to indicate one side over the other.) Then attach the POL connection of the hose to the propane tank, and the other end of the hose to the fuel filter. Verify all propane connections are tight before opening the valve on the propane tank. (I verified that with the hose attached to the left connector and the heater in operation, no propane comes out of the right connector.)

The control knob for the Big Buddy heater.

    Pushing down on the control knob and rotating it counterclockwise from OFF to the pilot light position will trigger a spark to ignite the pilot light. (If the pilot light doesn't light, rotate the knob clockwise toward OFF, and then counterclockwise toward PILOT to produce another spark. When the hose is first connected to the heater, it may take several attempts to purge the air from the hose.) Continue holding the knob down for a several seconds after the ignitionof the pilot light to allow the thermocouple to heat up. After the pilot light is stable, push down on the knob again and rotate counterclockwise to the LO (low, 4000 BTU) or MD (medium, 9000 BTU) position to light the left burner tile. After the left burner tile is lit and glowing a bright orange, you can rotate the knob counter clockwise to the HI (high, 18,000 BTU) setting to ignite the right burner tile.

    Unlike most gas heaters and stoves that can be adjusted continuously from low to high, the control knob on the Big Buddy heater only has discrete steps for burner operation - low, medium, and high.

    You can return the knob to the pilot setting if you just want to turn off the heat for a short period of time - the pilot light will remain lit. Note that the pilot light is an exposed flame.

    If you want to turn off the heater completely, close the valve on the propane tank, and let the heater burn off the propane in the hose. This will only take a couple minutes. Then turn the knob to the OFF position. Let the heater cool before detaching hoses or moving the heater.

At night, the Big Buddy heater gives off a
reassuring orange glow

Outdoor Operation

    While some promotional photos show the Big Buddy heater being operated outside, the pilot light may not remain lit if there is more than a slight breeze. And, with the breeze, it will take longer for the burner tiles to properly ignite than if the air is still. I would recommend using the heater only where it can be sheltered from the wind, such as in a tent or building.


    After evaluating several emergency heating options, I decided to purchase the Mr. Heater Big Buddy MH18B radiant heater, which was advertised to be safe for indoor use. To use the heater with a larger propane tank, I purchased a hose assembly and fuel filter. I also purchased a couple 20-pound propane tanks so I would have an adequate supply of fuel available.

    Doing some back-of-the-envelope calculations, a full 20-pound propane tank should operate the heater on high for 24 hours. Two one-pound disposable cylinders should operate the heater on high for 2.4 hours.

    I cannot tell you how well the Big Buddy heater heats my home, since at the time of this writing, it is August with typical hot Texas summer weather. All of my testing was performed outside.

    Honestly, I hope I never need to use this heater in emergency conditions like I experienced in February of 2021. But, several converging trends suggest I will likely need it sooner rather than later.


  1. They dump a TON of moisture when I've used them. The byproduct of combustion is water and CO2, and I'm betting that (not bothering to do the math) 20 gallons of water into your environment for each 20 gallons of propane burned. I have two of them.

    1. That might not be a bad thing depending on where one lives. Besides the fact that air is dryer in winter, using wood for heat seems to also dry the air in the house. While we now have a fireplace, I have a large kerosene heater as another backup (and actually used it to supplement our heating in my college days); the Japanese style heaters are designed to keep a kettle on it, both for the hot water but also the extra humidity.


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