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Mr. Heater · MH18B

Mr. Heater Big Buddy MH18B

Twice the Buddy: 18,000 BTU from two 1 lb cylinders or a 20 lb tank, for a two-car garage or a cabin, with the same low-oxygen shut-off.

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Amazon link · we earn a commission if you buy · $240 MSRP · Amazon price not shown · verified Sep 25, 2026

Why it scores 7.3

Reliability7.0
Performance8.5
Usability7.0
Value6.5
Support7.0

Reliability 30% · Performance 25% · Usability 20% · Value 15% · Support 10%. Bars run from 5 to 10.

Known issue · Mr. Heater removed the built-in fan from current Big Buddy production over tariffs without changing the price, so older listings and reviews describe a fan the unit no longer hasMr. Heater product page · hands-on

Built from 3 sources: 2 owner threads, 1 spec page.

Take it home if

  • Up to 18,000 BTU and 450 sq ft
  • Two cylinders or a 20 lb tank via the hose
  • Up to 11 hours on low from two cylinders

Walk past if

  • Current units ship without the fan and at the same price
  • Needs Mr. Heater's fuel filter on a hose or the regulator fouls
  • Seventeen pounds before fuel

Spec sheet

Manufacturer ratings, not our measurements.

Heat output
18,000 BTU max (9,000 mid, 4,000 low)
Coverage
About 450 sq ft
Run time
Up to 11 h on low from two 1 lb cylinders
Fuel
Two 1 lb cylinders, or a 20 lb tank with the hose and filter
Weight
17.1 lb
Safety
Oxygen depletion sensor, tip-over shut-off
Warranty
1 year

Alternatives

The nearest in its class, then the nearest rival among heaters.