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 and the Mr. Heater Big Buddy MH18B are evenly matched, rated 3.9 and 3.9. The ThermoMate PHF18B 18,000 BTU leads on safety and value. The Mr. Heater Big Buddy MH18B wins on warranty and fuel options. The ThermoMate PHF18B 18,000 BTU costs $70.27 less ($169.99 vs $240.26).
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 Big Buddy MH18B
#6 in PortableFull review
For heating a ventilated cabin, ice shack or large tent that a 9,000 BTU Buddy can’t keep warm. Give it the 18 sq in of fresh air at floor and ceiling the maker requires.
Mr. Heater $240.26$240.26
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) and value ($9.44 per 1,000 BTU ($169.99, 18,000 BTU) vs $13.35 per 1,000 BTU ($240.26, 18,000 BTU)).
- Choose the Mr. Heater Big Buddy MH18B 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 Big Buddy MH18B |
|---|---|---|
| Overall rating | 3.9/5 | 3.9/5 |
| Value 25% | 54 $9.44 per 1,000 BTU ($169.99, 18,000 BTU) | 29 $13.35 per 1,000 BTU ($240.26, 18,000 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 | 100 turns down to 4,000 BTU |
| Ignition 10% | 100 push-button piezo ignition | 100 push-button piezo ignition |
| Fuel options 5% | 50 runs on a bulk tank only | 100 runs on 1 lb cylinders or a bulk tank |
Independent measurements
ThermoMate PHF18B 18,000 BTU
No independent test published yet.
Mr. Heater Big Buddy MH18B
| Tested by | Heat output | Noise | Run time | Conditions |
|---|---|---|---|---|
| webBikeWorld | - | - | 2 h | Two 1 lb propane cylinders on high, reported by the owner as about 2 hours. The same review says it warmed an insulated garage from about 40 F to about 55 F in about 15 minutes. |
Specifications
| ThermoMate PHF18B 18,000 BTU | Mr. Heater Big Buddy MH18B | |
|---|---|---|
| Heating | ||
| Heat output | 6,000 to 18,000 BTU | 4,000 to 18,000 BTU |
| Type | Portable | Portable |
| Use | Job sites and garages | Indoor (ventilated) |
| Heats up to | 450 sq ft | 450 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 | Push-button piezo |
| Power needed | None | None |
| 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 | - |
| Weight | 14.6 lb | 17.1 lb |
| Warranty | 1 year | 3 years |