Every RV roof vent fan 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. Fans are grouped by lid, open lid and rain covered, and both groups use the same scales except for price.
| Factor | Measures | Weight |
|---|---|---|
| Price | price of the fan | 25% |
| Airflow | rated CFM on high, up to 25 per watt drawn | 15% |
| Speeds | number of fan speeds | 10% |
| Features | reversible fan, powered lid, thermostat, rain protection and remote | 25% |
| Warranty | warranty length | 25% |
Where the numbers come from
Airflow, speeds, features, current draw, roof thickness and warranty come from the maker’s product page, catalog, manual or spec sheet, and from the maker’s own copy on its Amazon listing when it publishes nothing else. Where a maker gives airflow in cubic meters an hour, it’s converted to CFM. Prices are checked at Amazon and the maker’s own store, and the lowest is used.
The factors
Price is the current price on a log scale, so a fan half the price always gains the same amount. Covered fans cost more to build, so each group has its own scale: an open lid fan scores zero at $400 and full marks at $120, and a covered fan scores zero at $550 and full marks at $250.
Airflow is the maker’s rated airflow on high: 300 CFM scores zero and 950 CFM full marks. Airflow ratings are the makers’ own and aren’t measured the same way from brand to brand. A fan can only move so much air for the power it draws, so where the maker publishes the current draw, airflow is credited up to 25 CFM per watt (12 V times the amps on high), and a higher claim is marked as estimated.
Speeds is the number of fan speeds: 3 scores zero and 10 full marks. A fan with automatic variable speed is counted by its fixed manual speeds.
Features adds up five things that let a fan run itself: a reversible fan that can blow in as well as out (25%), a powered lid that a motor opens and closes (20%), a thermostat (20%), rain protection (20%) and a remote (15%). On an open lid fan, rain protection means a sensor that closes the lid when rain starts; a covered fan gets that 20% automatically, since its cover does the same job.
Warranty is the maker’s warranty: 1 year scores zero and 3 years full marks. Where a maker gives a longer parts-only term after the full warranty, the full warranty term is used.
What isn’t scored
Current draw on high, blade size, a built-in light, the roof thickness it fits, weight and release date are listed but not scored.
Missing data
If a figure isn’t published, that factor gets the neutral middle score (50) and the product page marks it as estimated. Features is only neutral when none of the five is published; otherwise a feature the maker doesn’t list counts as absent. 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.