The Mr. Heater 20K Blue Flame Dual Fuel rates 4.2 among vent-free gas wall heaters; the Rinnai EnergySaver EX22DTN rates 3.9 among direct vent ones. The Mr. Heater 20K Blue Flame Dual Fuel costs $2,018.87 less ($199.99 vs $2,218.86).
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 $199.99The pick of the Rinnai range for a large living area or small cabin that wants quiet, even heat with real thermostat control. Pair it with a backup if outages are common.
Amazon $2,218.86Prices 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 | Rinnai EnergySaver EX22DTN |
|---|---|---|
| Overall rating | 4.2/5 | 3.9/5 |
| Value 30% | 64 $10 per 1,000 BTU ($199.99, 20,000 BTU) | 42 $103.20 per 1,000 BTU ($2,218.86, 21,500 BTU) |
| Heat output 15% | 50 20,000 BTU/hr | 38 21,500 BTU/hr |
| Controls 20% | 75 thermostat, electronic ignition | 100 thermostat, blower, electronic ignition |
| Fuel 5% | 100 runs on propane or natural gas | 0 natural gas only |
| Warranty 30% | 100 5-year warranty | 100 5-year warranty |
| Mr. Heater 20K Blue Flame Dual Fuel | Rinnai EnergySaver EX22DTN | |
|---|---|---|
| Heat | ||
| Venting | Vent-free | Direct vent |
| Heat type | Blue flame | Furnace |
| Maximum input | 20,000 BTU/hr | 21,500 BTU/hr |
| Minimum input | - | 8,200 BTU/hr |
| Heating area claim | 700 sq ft | - |
| Efficiency | - | 81% AFUE |
| Fuel and controls | ||
| Fuel | Dual fuel | Natural gas |
| Thermostat | Yes | Yes |
| Blower | No | Yes |
| Ignition | Electronic (battery) | Electronic (120 V) |
| Needs an outlet | No | Yes |
| Oxygen depletion sensor | Yes | - |
| Build | ||
| Weight | - | 51 lb |
| Warranty | 5 years | 5 years |
| Released | 2018-10 | - |
