Every gas wall heater gets a score from 0 to 100% built from five factors, which maps onto the 5-point rating shown on the site (a 0% score would be 1.5 stars; a perfect score, 5). Each factor is scored against fixed reference points, not against the other products in the list, so adding a new model never moves another model’s rating. Heaters are grouped by venting, vent-free and direct vent, and value and heat output use a separate scale for each group.
| Factor | Measures | Weight |
|---|---|---|
| Value | price per 1,000 BTU/hr | 30% |
| Heat output | maximum BTU/hr | 15% |
| Controls | thermostat, blower and electronic ignition | 20% |
| Fuel | runs on propane and natural gas | 5% |
| Warranty | warranty on the whole heater | 30% |
Where the numbers come from
Heat input, fuel, controls, ignition, safety features and warranty come from the maker’s manual, spec sheet or product page. Prices are checked at Amazon, the maker’s own store and home improvement retailers, and the lowest price at a store the page links to is used.
The factors
Value is the current price divided by the maximum input in thousands of BTU per hour, on a log scale, so halving the price per 1,000 BTU always counts the same. For vent-free heaters $25 per 1,000 BTU scores zero and $6 full marks; for direct vent heaters $250 scores zero and $30 full marks.
Heat output is the maximum input in BTU per hour. For vent-free heaters 10,000 BTU scores zero and 30,000 BTU full marks; for direct vent heaters 10,000 BTU scores zero and 40,000 BTU full marks.
Controls is 50% for a built-in thermostat that cycles or modulates the flame on its own, 25% for a blower that is built in or included in the price, and 25% for electronic ignition, battery or house powered. A push button piezo igniter and a manual valve score nothing here.
Fuel is full marks for a heater that runs on both propane and natural gas and zero for one that runs on only one of them.
Warranty is the maker’s warranty on the whole heater: 1 year scores zero and 5 years full marks. Longer terms on the burner or heat exchanger alone aren’t counted.
What isn’t scored
The lowest input setting, the maker’s heating area claim, efficiency (AFUE) on direct vent models, weight, whether it needs a 120 V outlet, the oxygen depletion sensor, the heat type (blue flame, infrared or furnace) and the release date are listed but not scored. Vent-free heaters sold in the US come with an oxygen depletion sensor, so it doesn’t separate them. Whether a heater is allowed where you live isn’t scored either: vent-free heaters are not allowed in California and are restricted in other places, often in bedrooms and bathrooms, so check local code.
Missing data
If a figure isn’t published, that factor gets the neutral middle score (50) and the product page marks it as estimated. The exception is warranty: a maker that doesn’t publish one gets no warranty counted, so that factor scores zero, the same as the shortest warranty on the scale, and is marked estimated.
Ties and discontinued models
Products are ranked by score within each group. Discontinued models stay listed but rank below every current model and can be hidden with the “Hide discontinued” filter.