RV Install and Review of the Mr. Heater Big Buddy MH18B

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Big Buddy Indoor Safe Propane Radiant Heater

While snowbirding in the US South West last winter we got the chance to do a substantial amount of dry camping out in the desert. I quickly discovered how much juice it took to run the big onboard RV furnace. My wife gets quite cold at night and requires a fair amount of heat to sleep comfortably. When the night time temps hit near freezing the furnace would run quite often along with it’s power hungry fan. By morning even my dual 6 volt Trojan golf cart type batteries would be run down. I did some research over the summer and discovered that many hard core boondockers use propane radiant heaters at night. A very popular and well thought of brand is the Mr. Heater. I narrowed my choice down to the Mr. Heater Big Buddy model MH18B and this Xmas Santa delivered me a shiny new one! I also picked up a 12 foot propane rubber extension hose so I could utilize a larger LP gas cylinder. The Big Buddy comes equipped to use small one pound disposable type cylinders but they don’t last to long and it is far more economical to use the larger RV LP gas cylinder.

Mr Heater Big Buddy Propane Indoor Safe Heater   Big Buddy on Low


When using the Big Buddy read and follow all safety precautions like proper ventilation and checking connections with soapy water for leaks. Link to Operation Manual –http://pdf.lowes.com/operatingguides/089301748156_oper.pdf

Installing the Propane Extension Hose in my Keystone Cougar 276RLS

Many folks will just run the hose through an open window but I decided I would like a little more permanent solution so I scoured the rig for a possible pathway. First I decided where I would like the heater to operate in the rig and the best spot for us is right in front of the entertainment center area. Here it can be placed on the vinyl flooring, off the carpet and is centered in the rig giving us nice even heating.

Big Buddy Heater in our rig
Big Buddy working in our rig

I had previously installed my 1000w inverters AC outlet below the entertainment area and knew if I removed the bottom panel I could make an access hole leading out to the RV water inlet plumbing area. My plan from there was to run the propane extension hose out through the rigs water closet hose port. Twelve feet of propane extension hose turned out to be a perfect length after fishing it through the rig there was plenty left to attach it to an outside LP gas cylinder and enough left inside to move the Big Buddy around a little bit. When not using the Mr. Heater Big Buddy the hose can be stored neatly and out of the way behind the wood panels.

Panel removed below entertainment area   Cut out an access hole for LP gas hose

Hose is fed through water inlet area   LP Gas hose coming out of rig

One little extra thing I did too help protect the rubber hose from damage was to enclose it inside some plastic tubing usually used for electrical wiring. This worked out well.

Showing Hose Covering
I added extra protection to the hose

Video Showing My Install and Demo of the Heater

*Update* –  I have had several people email to inform me the Big Buddy can be used with a low pressure quick connect port located next to one of the bottle hookup ports, I had pointed it out in the video but not in the text. There are hoses available for this and one person has even successfully modified his RV and T’ed off of the low pressure lines near the stove. I’m mention this for educational purposes and in no way recommending modifyiing the RV LP gas lines without consulting a certified professional. Mr. Heater also recommends using a fuel filter when utilizing the larger LP gas Cylinders to prevent impurites from clogging the heater. – Ray

My Review of the Mr. Heater Big Buddy MH18B

Overall I’m very pleased with the Big Buddy. It was well worth the $150 or so I spent for the unit and hose. I am most surprised with how much heat comes off the thing. It can easily warm up our 30 foot fifth wheel even on the lowest setting. When using the disposable one pound canisters the unit is completely portable. This will come in handy for us. We like to photograph sunrise and star trails and many times it’s quite cold, this little heater can come along and keep us warm.

Propane Bottle Hooked up   Side View showing propane hookups

Three Heat Levels   Twin Ceramic Heater Plates

There are many things to like about the Big Buddy but also a few short comings. Here are my Likes and Dislikes.


  • Provides lots of heat and includes 3 different levels.
  • Very smartly designed hookups making attaching the cylinders or hose a breeze.
  • Light weight with a nice big handle.
  • Compact for easy storage.
  • Built in Low Oxygen and Tip-Over Sensors for safety.
  • Most of the unit stays cool to the touch.
  • Good price for what you get.
  • Portability


  • Low run time when using 1 pound cylinders.
  • Built in fan sounds cheap and is makes a screeching sound sometimes.
  • Fan battery holder area cheaply made and makes loading the “D” batteries a little difficult.
  • Should come with 6 volt AC adaptor for fan.
  • Wish it had a 12volt instead of 6 volt input for fan power.
  • Pilot lighting / Heat Level Knob a little difficult to use. Have to wiggle it around sometimes.

My Big Buddy Photo Gallery

We have dry camped a few days now and used the Mr. Heater Big Buddy several times, it has performed very well. Our RV battery life has improved dramatically which means less hours running the generator. It’s so nice not to have to listen to the loud fan noise when listening to music, watching videos or TV. Also it’s convenient and quiet in the morning to flip it on and soon the rig is toasty warm. I like the fact that the heat is consistently radiated which maintains a nice even heat. Two “Love Your RV” thumbs up for our new friend the our Big Buddy.

Check out Amazon for the Big Buddy, hoses and accessories

Update – Had a great opportunity to further test out the Big Buddy. Spent 4 days at Joshua Tree NP. It is fairly high in elevation (4000 feet) so got near freezing every night. The Big Buddy easily heated the rig and I never even needed the high setting or fan option. We used it from sundown to bed time and in the morning until the sun warmed the rig. It worked great. I still prefer to use the regular RV furnace when sleeping but while awake it was so nice to have the silence and consistent heat of the Big Buddy. – Ray

Update March 2015 –  I’ve recently installed a low pressure quick connect port to my RVs LP Gas system. I was able to easily tee in to my Suburban furnaces input line. Check out the install details and video here.

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