Aug 2, 2020 at 11:03 am #3668136
Info in next post.Aug 2, 2020 at 11:06 am #3668137
I’m a bit late in posting this (peak mosquito season is ending for some areas), but I hope this is useful to others.
Thermacell mosquito repellers have a stated elevation limitation of 7,000 ft above sea level per the manufacturer. I’ve successfully modified Thermacell Portable and Backpacker models to operate consistently up to 12,000 ft.
I find Thermacells to work surprisingly well, and totally worth the weight if you plan to hang around camp very long. Put it next to you while you cook, eat, or enjoy the view, and there are far less mosquitos bothering you. My experience with them is in the mountains of Colorado, I don’t know if they would be effective in places like Alaska with more mosquito pressure.
If you already use a canister stove, the Backpacker model is the lightest option (4 oz), since you already have the fuel with you. Running the Thermacell for several hours a day will use very little fuel compared to what you will use for cooking. The disadvantage of your Thermacell sharing a fuel source with your stove is that you can’t use the Thermacell at the same time as cooking, when you may want to be able to sit and enjoy the scenery around you without mosquitoes in your face.
I prefer the Portable model (MR-300) so I can use it concurrently with my stove. It weighs 6.7 oz with a butane cartridge installed, but I always bring at least one extra cartridge with me too. The cartridges last 12 hours and weigh 1.0 oz each. Repellent pads (used with both models) last 4 hours and weigh 0.1 oz each.
The battery powered Radius model has only 6.5 hours of battery life, so I don’t find it useful for backpacking trips. Portable battery packs to recharge it would weigh much more than extra butane cartridges.
The short version version of the modification (similar process for both the Backpacker and Portable models):
Take apart the Thermacell. Find the air inlet on the white assembly. Enlarge the air inlet opening with a tiny file to allow more air to mix with the gas, for better combustion at elevation. I enlarged the air inlet by around 22% to target functionality at elevations of 7,000 ft to 13,000 ft. I have been successful in getting consistent operation at up to 12,000 ft (I haven’t tried higher yet).
Full write-up including more background info and detailed modification instructions at my website. I know there’s some stove experts and other scientific minds here on BPL, so feel free to provide feedback.
I have no affiliation with Thermacell.Aug 3, 2020 at 3:53 am #3668504Roger CaffinModerator
@rcaffinLocale: Wollemi & Kosciusko NPs, Europe
Allethrin, the active chemical in this, is reported as being very toxic to all aquatic life, and harmful to cats as well. It is mildly hazardous to bees.
CheersAug 3, 2020 at 5:14 am #3668509JCHBPL Member
@pastyj-2-2Aug 4, 2020 at 11:48 am #3668830Brad WBPL Member
Kind of the nuclear approach. Picardin or deet not an option?Aug 4, 2020 at 4:48 pm #3668904JPBPL Member
Thanks for the tip on how to improve the Thermacell. I have 4 thermacells including two backpackers. I always use the thermacell since I live in heavy mosquito territory. Even in light of the information above I will still use them. Deet sucks for many reasons and Permethrin doesn’t work for me on mosquitos, I use that for the wood ticks. If I have deet on well I’m going to wash off before bed and where else to wash off in the land of 10,000 lakes. That would be worse for the fish.Aug 4, 2020 at 4:54 pm #3668907Alice HengstBPL Member
@moondustLocale: Southern Sierras
I will try this, as I purchased the Thermacell a few years ago without having access to the fine print about the elevation limitation. Needless to say it has been in my gear box ever since (tried it once with NO luck, even below 7000 ft).Aug 4, 2020 at 6:16 pm #3668930
Thanks to JCH for the Extonet reference, and to all for the comments.
Everyone has their own personal comfort level with chemicals. For me, the manageable risk of allethrin is worth the benefit. Keep the repellent soaked pads away from streams and lakes, dispose of spent pads and packaging properly. Wash your hands after handling, or try not to touch the pads at all (handle only by the outside of the package). Per the Extonet reference, allethrin “degrades rapidly in the environment”, so the mist being released likely turns inert before it can cause much harm.
I do use DEET, although I don’t enjoy it. During the summer of 2019, the mosquitoes in Colorado were viscous. Using the Thermacell in conjunction with DEET worked well, and helped avoid needing to re-apply DEET every 2 hours in camp. I primarily backpack with my two young kids, so daily mileage is short, and we spend a lot of time in camp.
I didn’t find picardin to be very effective, or more specifically, not effective for very long. Hourly application was required to keep the bugs away. I tried the Sawyers lotion form, perhaps others are better.
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