Friday, October 7, 2022


Protect your furnace vent from LP-sniffing bugs

By Russ and Tiña De Maris

photo: shyamal on wikimedia commons

Frustrated with a frigid RV furnace, our friend Joe tried everything he could. The thing refused to light and made odd noises. He’d switch it off, wait, and try to relight it. The final relight cycle was the culmination. A hearty “Kaboom!” retorted like a cannon shot.

After ascertaining that certain muscles in his body hadn’t failed him at a critical and embarrassing time, Joe hustled outdoors from whence the noise had come. Sure enough, on the ground around his furnace vent were the telltale remains of a mud dauber nest. The poor creature had built her nest and laid a precious egg in the RV’s furnace vent, only to be swiftly evicted.

A word about mud daubers: These solitary wasps gather mud, roll it into balls and form small dirt nests. Into these small but cleverly constructed cells, stung (and thoroughly stunned) insects are placed, along with a solitary egg. Mama mud dauber flies away to work on the next nest, secure in her buggy knowledge that “junior” will have something to eat when hatched.

While this tear-jerking story from nature may cause some to reach for the tissues, the rest of us swear and curse the day that Mama found our RV. The common reaction: Head off to “RV MegaParts” and pick up a set of mud dauber screens. But be careful to not clog the vent so it can’t “breathe.”

RV furnaces and water heaters, like us, are air breathers. And like us, stick a little something extra over our nose (or vent) and you get what? A bit of an obstruction that can cause problems, particularly for RV appliances. Systems can operate in strange ways when not enough precious “breath” is available, and some RV technicians warn that obstructed “windage” can actually lead to premature appliance death. If you’ve priced out furnaces lately, you’ll want yours to last a long time. So be careful with the type of screen you use, if you go that route.

Otherwise, what to do? When not using the rig, tape over the vent, and post a note over the furnace thermostat or water heater switch warning the user to remove the tape before firing up the appliance. When in use, make checking out appliance vents a regular part of your walk-around routine. Worried about getting stung? If you spot a wasp nest, take a stick and remove it at night. We don’t recommend shooting the nest with wasp killer: Can you imagine what might happen if your wasp spray turned out to be flammable and your furnace “lit off” when you sallied forth with your can of Bug Off!? Ah, the picture it presents.

And one more thing: For some peculiar reason, it seems mud daubers are attracted to the scent of propane. On “light off” a bit of that odor is released, and that may be just enough to attract these little devils. Furnaces aren’t the only RV appliances that can become attractive. Water heaters and refrigerators also emit the attractive odor. One reader told us they had a siege of propane alarm signals driving them nuts. They took their rig to a technician who knew just where to look — in the refrigerator flue. Make sure your refrigerator roof vent screen is intact. And do periodic inspections of all your gas appliances!

You can get highly rated Camco mud dauber screens at Amazon.



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