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From a very young age, I grew up surrounded by bees. My father kept a few hives in our backyard for decades, and there were a few kind elderly in our neighbourhood who were keen to introduce me to beekeeping as a curious child. So, sometimes at home, sometimes in the neighbourhood, I helped with the bees, learning how to take care of them. As a child, I not only learned, but also loved bees with all my heart, listening to their buzzing around the trees during the gathering season, smelling the scent of the hive, watching the little bees "giving birth", licking the freshly spun honey.

Then I spent several years in cities for my studies. I got a degree in electrical engineering, then started working in the competitive sector as a test engineer, and for assembly and manufacturing companies. My engineering experience has grown over the years, and I've climbed the ranks. Along the way, I started a family, and a few years ago we settled in Etyek with my wife and our three young children. There was plenty of room for hives in our yard and I was looking forward to spending time again - even if only with a few hives - with my favourite hobby, beekeeping! I started out with ten hives, then increased to twenty. I thought I could manage that many hives while still having a job and a family. Etyek seemed to be an excellent choice for beekeeping, as experience so far has shown that bees can find foraging all year round without having to migrate. There are lots of chestnut trees, patches of acacia woods, fields provide sunflowers, even the alfalfa was honeyed last year. It was also in this area that I was introduced to the tree of heaven, or rather its special flavoured honey!

But along with the bees came the mites, and the experimentation began to see what would work against them. First I turned to the traditional method, the chemicals. I had been treating the bees with amitraz for years, but I didn't like the fact that the poison would build up and the mites could become resistant. It made me think particularly when all my father's colonies perished in one winter. I wanted to use a more natural, organic solution, so as not to harm the bees or the honey - and through that, ourselves. I turned my attention to natural acids, read about oxalic acid sublimation and was immediately attracted. As a hobby beekeeper, I didn't want to invest a lot of money, so I bought a cheaper device. It was a heat gun vaporizer. I was disappointed to find that my families were failing and weakened despite the treatment. I had followed the manufacturer's instructions. I couldn't help it, I had to turn to amitraz again and it seemed that the oxalic acid treatment was not working. However, I have heard time and time again from trusted beekeepers that they have been using oxalic acid sublimation for years and it works for them against mites. I must be doing something wrong!

I started to look into the subject more and more, and my research led me to the conclusion that temperature and controlled levels of oxalic acid play an important role in vaporizing. If the temperature of the heated chamber is too high, the oxalic acid is converted to formic acid, and at even higher temperatures it decomposes to carbon dioxide. So I set about trying out several types of oxalic acid vaporizers currently on the market. The first problem I encountered was overheating: the heated chamber would reach temperatures up to 15-30°C above the set point. And what surprised me was that the vast majority of mains-powered appliances are sold worldwide. Although I have my hives in my backyard and can do the job with an extension cord, I hadn't dared to think how cumbersome sublimation in the middle of a forest could be. That's when my engineering experience came into play, as I had a hunch that it could be technically feasible to do it with a battery, and that overheating could be improved. Although there are a couple of battery powered machines, they are very expensive and I didn't like the way they worked, even untested.


So I set out along this line: to develop an oxalic acid device that controls the temperature of the heated chamber much more accurately and runs on battery power. Experimenting was a long way with its ups and downs. In the end, by designing the heating of the chamber, the insulation and the temperature control, I managed to achieve a combination where the necessary heat could be produced efficiently, with so little loss that the necessary energy could be provided by a battery. The control of the heating is a key part of this, as not only is there no overheating - and therefore more reliable operation - but the energy waste associated with overheating has been eliminated. What is interesting here is that although many vaporizers have digital, PID temperature controllers, they do not make use of the PID function, but simply act as thermostats. They are set to only switch on and off at the given temperature. But the point of the PID function is to set the precision with which the temperature is controlled, and the overshoot. The other major difference that I realised during the development is that I have abandoned the often used slab heating for the chamber and instead heated the bottom of the chamber. As the cold oxalic acid settles on the bottom of the cauldron during the treatment and starts to cool it, if I put the heating there, the unit can reheat faster and more flexibly. And the insulation not only helps to reduce heat loss, it also ensures reliable operation even in extreme weather, and I'm thinking here in particular of windy weather.

However, other challenges for the vaporizer have also been encountered: the need to ensure that the outlet pipe does not clog so often; that it does not have to be held but stays on its own on the side of the hive during treatment; and that the dosing of oxalic acid is precise and simple. In short, an easy-to-use machine would be needed in all respects. Again, I had to rely on my engineering experience: having been involved in manufacturing and product development for many years, I already knew how to solve problems of this kind. But even so, it was a difficult journey to meet these needs point by point.

The first machine was a 12 volt version, 20 amps, 240 watts. I had a beekeeper friend help me test it, and he was able to treat 240 colonies with 2 gram doses on an 80 amp working battery without running out of power. Although I had considered an 18-volt version, I thought there would not be much demand for it, so I postponed its introduction at the beginning. I was wrong. As word of the device spread, more and more people asked if I could come up with such a version. So, with some modifications, an 18-volt version was born, which can be powered by Parkside, Einhell, Metabo, Makita, Milwaukee, Bosch batteries. Whatever brand of battery socket the beekeeper asks for, that's the socket I fit the vaporizer with. The 18 volt unit is also 240 watts and draws 13 amps. It takes about ~1 amp hour to heat up, and with 1 amp hour capacity, ~10 doses of 2 gram treatments can be made. As an example, once the device is heated, a charged 4 amp Parkside battery can treat 42 families with 2 gram doses at 20 Celsius degrees outside. It was important not to waste time when dosing the oxalic acid, so I developed a compact dispenser unit with a push button that can be adjusted to the amount of oxalic acid to be dosed by turning the push button up to 1-4 grams, which can be read immediately from the indicator on the dispenser unit.

I continue to develop the device. I also welcome feedback directly!

János Fenyősy

(the above article appeared in the March 2022 issue of Beekeeping magazine in Hungary)