ThermoMate PHF18B 18,000 BTU
#5 in PortableFull review
For ventilated garages, workshops and job sites where a rolling 18,000 BTU cabinet heater beats a tank top. The manual rules out homes, RVs and living quarters.
Amazon $169.99$169.99
The ThermoMate PHF18B 18,000 BTU is the better propane heater overall, rated 3.9 to 3.6. The ThermoMate PHF18B 18,000 BTU leads on safety, turndown and value. The Mr. Heater Buddy FLEX MH11BFLEX wins on warranty and fuel options. The Mr. Heater Buddy FLEX MH11BFLEX costs $40.99 less ($129 vs $169.99).
Prices were last checked November 11, 2026. Product prices and availability are accurate as of that date and are subject to change; the price and availability shown on Amazon or the retailer's site at the time of purchase apply. As an Amazon Associate we earn from qualifying purchases.
Mr. Heater Buddy FLEX MH11BFLEX
#8 in PortableFull review
A compact, push button alternative to the Portable Buddy for ventilated tents and cabins, with a slightly higher low setting. Keep the fresh air the maker’s manual requires.
Amazon $129$129
Which should you buy?
- Choose the ThermoMate PHF18B 18,000 BTU for safety (CSA listed, low-oxygen shutoff, tip-over shutoff vs low-oxygen shutoff, tip-over shutoff; no safety listing published), turndown (turns down to 6,000 BTU vs turns down to 8,000 BTU) and value ($9.44 per 1,000 BTU ($169.99, 18,000 BTU) vs $11.73 per 1,000 BTU ($129, 11,000 BTU)).
- Choose the Mr. Heater Buddy FLEX MH11BFLEX for warranty (3-year warranty vs 1-year warranty) and fuel options (runs on 1 lb cylinders or a bulk tank vs runs on a bulk tank only).
Scores side by side
Each factor is scored 0-100 against the same fixed reference points for every portable propane heater; a clear win is highlighted. How we rank explains each one.
| Factor weight | ThermoMate PHF18B 18,000 BTU | Mr. Heater Buddy FLEX MH11BFLEX |
|---|---|---|
| Overall rating | 3.9/5 | 3.6/5 |
| Value 25% | 54 $9.44 per 1,000 BTU ($169.99, 18,000 BTU) | 39 $11.73 per 1,000 BTU ($129, 11,000 BTU) |
| Safety 30% | 90 CSA listed, low-oxygen shutoff, tip-over shutoff | 50 low-oxygen shutoff, tip-over shutoff; no safety listing published |
| Warranty 15% | 0 1-year warranty | 100 3-year warranty |
| Turndown 15% | 95 turns down to 6,000 BTU | 39 turns down to 8,000 BTU |
| Ignition 10% | 100 push-button piezo ignition | 100 electric ignition |
| Fuel options 5% | 50 runs on a bulk tank only | 100 runs on 1 lb cylinders or a bulk tank |
Specifications
| ThermoMate PHF18B 18,000 BTU | Mr. Heater Buddy FLEX MH11BFLEX | |
|---|---|---|
| Heating | ||
| Heat output | 6,000 to 18,000 BTU | 8,000 to 11,000 BTU |
| Type | Portable | Portable |
| Use | Job sites and garages | Indoor (ventilated) |
| Heats up to | 450 sq ft | 275 sq ft |
| Thermostat | No | No |
| Fan | No | No |
| Fuel and power | ||
| Fuel | Bulk tank | 1 lb cylinder or bulk tank |
| Hose included | Yes | No |
| Ignition | Push-button piezo | Electric |
| Power needed | None | Batteries |
| Safety | ||
| Safety listing | CSA | None published |
| Low-oxygen shutoff | Yes | Yes |
| Tip-over shutoff | Yes | Yes |
| Build | ||
| Noise | 32 dB | - |
| Dimensions | 15 x 11.3 x 21.7 in | 13.5 x 9 x 14.25 in |
| Weight | 14.6 lb | 11 lb |
| Warranty | 1 year | 3 years |
| Released | - | 2019-08-22 |