Many standard RV fans are modest performers. Fortunately fans come in standardized sizes, making it easy to upgrade. Roof vents are 14 x 14 inches in the main living area and possibly in the bedroom, and probably 6 x 6 inches in the bathroom. Even vents without fans are likely to be 14 x 14. There are quite a few reasons to replace a fan, even if it’s working properly: Increase airflow. Some fans, even the same size, can move more air. Airflow is measured in CFM—cubic feet per minute. Improving airflow helps to cool indoor temperatures. Boosting airflow in the bathroom reduces odors and prevents mold. Reduce noise. Some standard vent fans are noisy—doubly irritating if they’re not efficient. Add features. You can boost ease of use with a temperature sensor, rain sensor, remote control, multiple speeds, reversible blades or a rain hood. Protect a pet. Leaving a dog or cat in the RV is dangerous without certain fan features. The best way to choose a fan upgrade is to answer some questions before buying: What’s my budget? Standard-grade roof vent/fan replacements cost about $60 to $110 for manual models. Installation would be extra, but many RV owners can install a fan themselves. They are powered by 12V wiring. Adding features raises the price, but significant upgrades don’t cost much individually. A model with remote controller, electric lift, built-in rain hood plus temperature sensor costs about $240 to $300. Aftermarket rain hoods range from $25 to $75. Prices vary by as much as 50 percent for the same model, so shop around, and remember that there’s never a need to pay list price. What color do I want? Inside, just about every fan is colored white or off-white. The most common color choices for lids are white and smoke. The smoke lids allow a bit of extra light to enter your RV. Some fans have clear blades, admitting even more light. Rain hoods are available in a variety of colors, but most common are white, beige, grey and black. Is remote control worthwhile? Some see this as unnecessary, but remote control eliminates having to reach up to turn the unit on or off, get up from your seat to change a setting, or run wiring to a wall switch. Remote control is a boon for short RVers and those with disabilities. It will add maybe $35 to the price of an otherwise similar unit. Do I want my fan to close automatically in the rain? Most fans shouldn’t run in the rain, but after you open manual fans and turn them on, they keep running, even if it pours. Not only would rain enter the RV, but it also would damage the fan motor. Consider a model with a rain sensor, such as the Fantastic Fan 803350. It will turn off and close when rain hits. The one problem on any fan of this type is a rain sensor may stay wet, preventing the vent from reopening and the fan from coming back on—potentially deadly for pets. Do I want to run my fan in the rain? If you want to exhaust air in the rain, avoid the rain sensor but get a model with a rain hood, such as the Dometic EZ-Breeze Vent Fan, about $90. It allows use 24/7, rain or not. The MaxxFan Model 00-07000k, about $300, pops open under a built-in rain hood but closes almost flat and has a temperature sensor, plus remote control. An alternative is to find a fan you like and add an aftermarket rain hood, such as the Maxxair 933067, about $50. Less expensive hoods are available. Make sure the hood you buy won’t significantly reduce airflow. The more venting the hood has on its rear surface, the better. Must I cool a pet while I’m away? You have to care for your pet, even if you’re not physically in your RV. The right roof fan helps. Just as important as leaving food and water is maintaining a safe temperature—ideally below 76F, and definitely below 80F. The best way to do that is to have a vent fan running. In addition to buying a model with a hood to allow use in the rain, or installing an aftermarket fan hood, get a fan with a temperature sensor, such as the Maxx Fan Model 00-07000k. In addition to shedding rain with its built-in hood, it cycles on and off to maintain the temperature, even if you’re not there. Do I want a temperature sensor? Even if you don’t have a pet, you might want this feature. The fan will automatically cycle on and off if the interior temperature reaches certain levels. That kind of comfort and convenience is nice to have for the few dollars a thermostat adds. It’s available on many fans in the $125-to-$150 range. Do I want to bring air in as well as exhaust air? During the spring or fall, or in the evening or morning, you may want to bring air in. This would be true especially if you have limited screened windows. To do so, you’ll need a vent/fan that can reverse its blades. How much air does a fan move? This might be especially useful to know in bathroom fans. You can’t easily increase the size of a bath fan to improve airflow, but you can increase airflow with a better motor and more efficient fan blades. Look at the CFM rating. How noisy is the fan? Unfortunately, many manufacturers don’t provide noise figures, measured in decibels (dB). If the product description doesn’t include the information, call the manufacturer or email to find out. There’s no guarantee, but a better-quality, more expensive motor and a higher number of blades typically increase air movement while lowering noise.