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Mr Heater Big Buddy Portable Heater (18000 BTU, MH18BX) - Campervan HQ

Mr Heater Big Buddy Portable Heater (18000 BTU, MH18BX)

  • $ 149.99
  • Save $ 10

Note: This heater has been discontinued.

Looking for an efficient RV heater? The Mr. Heater Big Buddy Portable Heater (18000 BTU, MH18BX) is a power- and fuel-efficient alternative to the standard RV forced-air propane furnace. Unlike the standard furnace, this heater does not have an open flame, though it does have a small electric fan for heat dispersal. The Mr. Buddy portable heaters operate on LP gas. For extra safety, this heater has two types of shut-off switch: a tip-over switch and an oxygen depletion sensor (ODS).

How does a catalytic heater work? When the catalytic heater is turned on, the heater's grid is preheated with an electric heating element embedded within the ceramic structure that supports the catalyst layer.  Once the catalyst has reached 300°F, a thermo switch in the back of the heater closes, and gas is dispersed across the back of the heater, mingling with the catalyst. The hot catalyst and oxygen ignite the gas, causing a flameless combustion reaction, producing heat.

This model is a larger version of the small portable Buddy heater (9000 BTU, MH9BX). The Big Buddy can be set to heat at 4000 BTU, 9000 BTU and 18000 BTU heating levels, heating up to a 450 sq. ft. indoor space.

Warning: Catalytic heaters burn fuel, so they require oxygen and produce trace amounts of exhaust gases (~100 ppm CO, ~1500 ppm hexane, CO2 and water vapor). For safe use in your RV, you must keep a window or vent open so there is an adequate supply of oxygen for the heater and the occupants of the RV. Also, ensure you have functioning CO and LP gas detectors in your RV.

Safety notes: Laws differ state-by-state in the US on vent-free gas appliances, as shown in this list of state vent-free gas appliance regulations. Also, clearances from combustible materials must be a minimum of:

  • 4" from each side
  • 4" from the floor (rug, tile, etc.)
  • 18" from the top
  • 30" from the front
  • 0" from the rear

Key Features: Mr. Heater Big Buddy Portable Heater (18000 BTU, MH18B)

  • 4000, 9000 or 18000 BTU/hr
  • For use with LP gas (propane)
  • Safe for operating at altitudes up to 7000 feet ASL
  • Heats up to 450 sq. ft.
  • Fan operates on 4 D batteries or AC adapter
  • Single control start knob
  • Hi-Med-Low heat settings
  • Swivel regulator
  • Fold-down handle
  • Accidental tip-over safety shut-off
  • Piezo ignitor
  • Runs off two 1 lb. propane cylinders
  • Connects directly to a 20 lb. propane cylinder with optional hose and filter
  • 1-year limited warranty.

Specifications: Mr. Heater Big Buddy Portable Heater (18000 BTU, MH18B)

Height(in.) 15
Width (in.) 12
Depth (in.) 19
Weight (lbs.) 17.1
Fuel Usage

0.099 gph @9000 BTU,

0.044 gph @4000 BTU.



Approvals AGA, CGA

Video: Mr. Heater Big Buddy Portable Heater



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