The Mr. Heater 20K Blue Flame Dual Fuel rates 4.2 among vent-free gas wall heaters; the Williams 2203822 Direct Vent Furnace rates 2.5 among direct vent ones. The Mr. Heater 20K Blue Flame Dual Fuel costs $949.01 less ($199.99 vs $1,149).
A thermostat blue flame heater for a living room or cabin of up to about 700 sq ft that may switch between propane and natural gas. The long warranty sets it apart.
Amazon $199.99For a living area or small house on natural gas where heat during outages and a low price matter most. Budget for the thermostat and a licensed installer.
HVACDirect $1,149Prices were last checked November 2, 2026 and are subject to change; the price and availability shown by the retailer at the time of purchase apply.
These two sit in different venting classes (vent-free and direct vent), and each is scored against the reference points for its own class, so a rating says how well each does among its own venting peers. How we rank explains each factor.
| Factor weight | Mr. Heater 20K Blue Flame Dual Fuel | Williams 2203822 Direct Vent Furnace |
|---|---|---|
| Overall rating | 4.2/5 | 2.5/5 |
| Value 30% | 64 $10 per 1,000 BTU ($199.99, 20,000 BTU) | 74 $52.23 per 1,000 BTU ($1,149, 22,000 BTU) |
| Heat output 15% | 50 20,000 BTU/hr | 40 22,000 BTU/hr |
| Controls 20% | 75 thermostat, electronic ignition | 0 manual control, push button ignition |
| Fuel 5% | 100 runs on propane or natural gas | 0 natural gas only |
| Warranty 30% | 100 5-year warranty | 0 1-year warranty |
| Mr. Heater 20K Blue Flame Dual Fuel | Williams 2203822 Direct Vent Furnace | |
|---|---|---|
| Heat | ||
| Venting | Vent-free | Direct vent |
| Heat type | Blue flame | Furnace |
| Maximum input | 20,000 BTU/hr | 22,000 BTU/hr |
| Heating area claim | 700 sq ft | - |
| Efficiency | - | 67% AFUE |
| Fuel and controls | ||
| Fuel | Dual fuel | Natural gas |
| Thermostat | Yes | No |
| Blower | No | No |
| Ignition | Electronic (battery) | Push button |
| Needs an outlet | No | No |
| Oxygen depletion sensor | Yes | - |
| Build | ||
| Warranty | 5 years | 1 year |
| Released | 2018-10 | - |
