Powered Roof Vents

Choosing a powered roof vent fan

Almost all of these drop into the same 14" x 14" roof opening, so the decision isn't about fit — it's about how much fan you want. A basic exhaust-only unit clears heat and odors on a budget. A reversible, multi-speed fan with a rain shield is what most full-timers and boondockers end up wanting, because it works in weather and moves serious air. Here's what separates them:

• Speeds and direction. A 4-speed exhaust-only fan like the Original Maxxfan pulls air out and that's it. The Maxxfan Deluxe runs 10 reversible speeds, so you can exhaust a hot galley or pull cool air in over the bed.
• Rain shield and lid. The Maxxfan's built-in cover lets it run with the lid up in the rain — a real advantage over a plain vent you have to close the second clouds roll in. The Dome Plus is the low-profile 6" version for vans and smaller builds.
• Lift and controls. Manual-lift models use a knob or crank; powered-lift Deluxe units open and close on a remote with a thermostat that cycles the fan to hold a set temperature.
• Power and switches. These are 12-volt fans wired to your house battery. If you're replacing a bare crank vent, you'll need a switch — an RV Designer toggle rated 8A at 125VAC handles a basic install.
• Repair parts. Before you replace a whole unit, check the cheap stuff. A stripped Heng's drive gear is a common reason an older vent won't crank open, and it's a few-dollar fix.

If your fan still opens fine and you only need to move air better, a full replacement may be overkill — sometimes a new gear or switch does it. When the lid itself is cracked or sun-baked, that's a vent lid or cover job instead. And to keep the heat out when the fan's off, drop in a reflective vent insulator.