Comparison Summary
The Mr. Heater MH9BX Portable Buddy Midnight Series is the most versatile starting point for supervised spot heat: it runs at 4,000 or 9,000 BTU and connects directly to a 1 lb propane cylinder. Its stated reach is up to 225 sq. ft., so it is not the choice for a large room. For supplemental heat in a larger designated room, the Mr. Heater F299830 pairs a 30,000 BTU radiant burner with a thermostat and a stated reach of up to 1,000 sq. ft.; it requires an appropriate propane supply and installation rather than a cylinder attached at the heater.
The blue-flame Mr. Heater F299720 is a room-oriented alternative with a lower 20,000 BTU output. The Big Buddy F274805 extends portable output to 18,000 BTU but needs more fuel for its highest setting. For a smaller wall or floor unit, the two 10,000 BTU ProCom models offer a choice between blue-flame convection and directional infrared heat. Check exact-model instructions and local restrictions before choosing any vent-free heater: indoor labeling and an oxygen-depletion shutoff do not make combustion risk disappear.
Buying Guide
Sizing and Capacity
Start with the area where people need warmth, then decide whether you want to aim heat at occupants or supplement a room. The MH9BX offers two settings and a stated 225 sq. ft. reach. Both Big Buddy versions reach 18,000 BTU and claim up to 450 sq. ft., but their highest setting changes the fuel needed. The ProCom 10,000 BTU units claim up to 500 sq. ft.; the Mr. Heater room units span stated coverage of 700 to 1,000 sq. ft. Those figures come from product information under different conditions, so do not treat them as a controlled comparison or size a heater solely by floor area. Insulation, layout, and the amount of heat already available also affect suitability. Check the room’s required combustion and ventilation air before deciding that its square footage makes a vent-free unit appropriate.
Feature Tradeoffs
Radiant models direct warmth toward people and nearby objects, making the portable Buddies and the ProCom ML100TPA-B sensible when the occupied area matters most. Blue-flame models such as the F299720 and ML100TBA-B rely on convection for a more room-oriented approach. A thermostat on the vent-free room heaters is useful when you want temperature-responsive operation; the portable Buddies instead offer selectable heat settings. The F299430 adds propane-or-natural-gas flexibility, but it is worth choosing only if that flexibility justifies its more involved fuel setup. An oxygen-depletion sensor is a shutoff feature, not a carbon-monoxide alarm or permission to ignore ventilation instructions.
Best For, Avoid If
| Profile |
Recommended Product |
Why It Fits |
Avoid If |
| Household seeking supervised, movable outage heat |
Mr. Heater MH9BX Portable Buddy Midnight Series |
The MH9BX combines a direct 1 lb cylinder connection with 4,000 and 9,000 BTU settings. |
You need to supplement a large room or want a thermostatically controlled wall unit. |
| Buyer planning supplemental heat for a larger permitted room |
Mr. Heater F299830 30,000 BTU Radiant |
The F299830 offers a 30,000 BTU radiant burner, thermostat, and stated coverage up to 1,000 sq. ft. |
You cannot provide a compliant separate propane supply and suitable installation. |
| Buyer who prefers room-oriented convection at a moderate output |
Mr. Heater F299720 20,000 BTU Blue Flame |
The F299720 pairs 20,000 BTU blue-flame heat with a thermostat and mounting options. |
You need a heater you can carry between locations. |
| Buyer needing more supervised portable output than the MH9BX provides |
Mr. Heater MH18B Big Buddy F274805 |
The F274805 Big Buddy offers three settings up to 18,000 BTU. |
You expect one 1 lb cylinder to sustain its highest setting. |
| Buyer fitting a smaller permitted room with a compact blue-flame unit |
ProCom ML100TBA-B 10,000 BTU Blue Flame |
The ML100TBA-B combines a 10,000 BTU ceiling, thermostat, and included wall or floor placement parts. |
Your heat demand calls for substantially more than its listed output. |
| Buyer with a legitimate reason to retain two fuel options |
Mr. Heater MHVFDF30RTT Dual Fuel Radiant |
The F299430 is specifically designed for propane or natural gas and includes a fuel selector. |
You want a simple portable propane heater or cannot arrange the correct fuel connection. |
Key Specs to Compare
Read BTU figures alongside their settings: 4,000/9,000 for the MH9BX, 4,000/9,000/18,000 for either Big Buddy listing, and a 10,000, 20,000, or 30,000 BTU class for the selected room heaters. Next check the exact fuel named on the unit. The F299430 is dual fuel; the other selected models are presented as propane heaters. Do not assume a wall heater accepts a disposable cylinder because a Buddy does. Finally compare ignition and optional electrical features: battery-powered ignition does not mean the F299830 or F299720 needs a household outlet, while a fan is a distinct feature to confirm on the F274800. The F299820’s published 18,000-versus-20,000 BTU discrepancy and the F299730’s conflicting coverage figures warrant checking the label and current manual.
Setup and Handling Considerations
The MH9BX attaches to a 1 lb cylinder; the Big Buddy models accommodate cylinder-based portable use but need an adequate fuel arrangement for high output. Moving from a disposable cylinder to a 20 lb tank requires the compatible optional hose and, where specified, a filter. Confirm tank-placement rules in the exact manual rather than assuming a larger cylinder belongs indoors. Vent-free wall or floor models are a different project: feet or mounting hardware may come in the box, but a suitable gas supply and connection still have to be arranged. Mr. Heater specifies that the propane cylinder for its selected vent-free room heaters must remain outdoors and does not include their hose and regulator. Follow the manual’s clearances, ventilation instructions, and applicable installation rules; included mounting parts do not make every room or fuel connection suitable.
Maintenance and Longevity
Keep the exact model number when buying a hose, filter, fan, or replacement part. Mr. Heater specifies approved Buddy-series connections and warns against unauthorized attachments; a hose that fits is not necessarily approved for that heater. For a room unit, maintain the ignition battery where applicable and follow the manual’s instructions for inspecting the burner, pilot, and gas connections. If a heater repeatedly shuts off, will not light, or gives an unexpected odor, stop using it and follow the manufacturer’s troubleshooting and service guidance rather than bypassing a safety device. Before seasonal use, inspect the heater and its connection equipment according to the manual and replace damaged components with parts specified for that model.
Reliability Signals
Look for indoor-use identification, an accessible exact-model manual, named shutoff features, and clear fuel and installation requirements. The MH9BX and Big Buddy documentation identify both low-oxygen and tip-over shutoffs; the selected vent-free wall units specify low-oxygen shutoff but should not be presumed to have portable-heater tip-over switches. These distinctions matter more than a blanket ‘safe indoors’ phrase. Check location limits as carefully as features: Mr. Heater restricts Buddy indoor use in Massachusetts, restricts use in California dwellings, and lists additional location restrictions for its vent-free room heaters. Local rules and the current label govern the purchase, even when a retailer calls a model an indoor heater.
How to Compare Reviews
Match any account you read to the SKU, fuel, and intended setup before applying it to your choice. An MH18B account may concern the F274805 no-fan version rather than an F274800 PRO with the advertised fan; ask whether the pictured and shipped unit match. For the MH9BX, separate experiences with a direct 1 lb cylinder from those involving an optional 20 lb hose and filter. For the F299820, check whether the reviewer identifies the unit’s actual BTU label instead of resolving the published discrepancy by assumption. Comments about a wall heater also become more useful when they identify its propane connection, room conditions, and installation arrangement. A report about another fuel version or a different Big Buddy configuration cannot settle those questions.
Common Mistakes
Do not select an outdoor heater for a home merely because it burns propane, or treat an indoor-use label as approval for every state, bedroom, bathroom, or recreational vehicle. Mr. Heater’s selected vent-free room-heater documentation rules out bathrooms, bedrooms, and RVs. Do not turn a low-setting runtime into an all-settings promise: the MH9BX’s stated 5.4 hours on a 1 lb cylinder applies to low heat. Avoid buying a wall unit on the assumption that included feet also include the fuel connection. Most importantly, do not leave a burning heater unattended or use one while sleeping. Provide the air required by its manual, use a working carbon-monoxide alarm, and never treat an ODS or tip-over switch as a substitute for either.
Frequently Asked Questions
Is an indoor-rated propane heater safe to run while I sleep?
No. Do not leave these heaters burning unattended or run one while sleeping. Follow the exact model’s operating and ventilation instructions, and use a working carbon-monoxide alarm. An oxygen-depletion shutoff is not a replacement for those precautions.
Can I put a 20 lb propane cylinder inside beside a vent-free wall heater?
Do not assume so. Mr. Heater specifies that the cylinder for its selected vent-free room heaters remains outdoors. The Buddy models use a different portable arrangement; connecting one to a larger tank requires the approved optional equipment and the tank-placement instructions in its manual.
Do these heaters work during an electrical outage?
The MH9BX uses radiant heat without household electricity. Several selected vent-free room heaters also operate without household power, although their electronic ignition uses a battery. If a fan matters to you, confirm the exact Big Buddy configuration and its power requirements rather than assuming every MH18B includes one.
Should I choose blue flame or radiant heat?
Choose based on where warmth is needed. Radiant models emphasize heat directed toward occupants and nearby surfaces; blue-flame models use natural convection for a room-oriented approach. Then check output, controls, installation, and indoor-use eligibility: heat type alone cannot establish whether a model fits your room.
Final Recommendation
Choose the Mr. Heater MH9BX Portable Buddy Midnight Series for supervised, movable warmth in a smaller eligible space. Its two settings and direct 1 lb cylinder connection make the use case straightforward, provided you follow its indoor-use and ventilation limits. If you are instead equipping a larger permitted room for supplemental heat, the thermostatically controlled Mr. Heater F299830 30,000 BTU Radiant is the better fit—once its separate fuel supply and installation requirements are accounted for.
