Camco FUR500 RV Furnace Bug Screen | Atwood Hydroflame

If you've ever fired up the furnace on the first cold night of the season and heard it try, click, and lock out, there's a good chance a bug got there first. Wasps and mud daubers treat an open furnace exhaust vent like a pre-built condo. They pack it with mud and larvae over the summer, and by fall that nest is blocking the airflow your furnace needs to prove its sail switch and stay lit. The Camco FUR500 is a simple fix. It's a stainless steel screen that covers the exhaust vent on Atwood Hydroflame furnaces that don't have an outside access door, so the bugs stay out and the air still flows.

Fitment matters here, so let's be clear about it. This screen is built for the 3-5/8 inch round exhaust vent found on Atwood Hydroflame furnaces without an access door. Those are the sealed-vent designs, the ones where the only thing you see on the sidewall is the exhaust, not a hinged door. If your furnace has a separate access door, this isn't the right screen for it. And it's sized for the furnace vent specifically, so don't try to press it onto a water heater vent or a dryer exhaust. Measure your vent opening before you order. 3-5/8 inches across, a little over an inch and a quarter deep, is what this one fits.

The screen itself is stainless steel mesh, and that choice does real work. Stainless doesn't rust or corrode the way plain steel does, which is exactly what you want on a part that lives outside in rain, road salt, and sun for years. The mesh is tight enough to stop a wasp but open enough that it doesn't choke the exhaust. That's the balance that matters. Too fine and you starve the furnace, too coarse and the bugs walk right through. Camco has been making these a long time, and the spacing is dialed in for the job.

Installation is about as easy as RV gear gets. The FUR500 comes with two spring fasteners and a small installation tool, and that's all you need. No drilling, no screws, no sealant. The spring clips grab the lip of the vent and hold the screen in place, and the tool helps you seat them without fighting the tension by hand. Most folks have it on in a couple of minutes. When it's time to pull it for cleaning, the same clips let you take it back off without damaging anything.

Once it's on, it mostly takes care of itself, but give it a look each season. Pop the screen, clear out any leaves or spiderwebs that have collected behind it, and check that the mesh is clean before you rely on the furnace for a cold trip. This is a good one to add to your spring shakedown and your fall winterizing list. Snowbirds heading south, weekend campers, and full-timers all run into the same nesting problem, and the fix is the same. A few dollars of stainless mesh up front beats a service call and a cold night when the furnace won't stay lit.

In the box you get a single FUR500 screen, the two spring fasteners, and the installation tool, along with an English and French language package. It's Camco part number 42144. If you run more than one rig, or you just want a spare on the shelf, they're cheap enough to keep an extra around. It's the kind of small part that saves you a big headache. And once you've cleaned a wasp nest out of a furnace vent, you won't want to skip it again.