Happy Friday! Apologies for the novella below, but I have some actual
knowledge to share with you folks today.
Let's talk about heating coils, and how to improve the performance of the Flux Deluxe!
As we know, the Dynavap + IH combo usually works quite well, but occasionally this combination produces disappointing results, e.g., sometimes an IH will heat a vapcap enough to click it, but the heat it generates is mysteriously insufficient to achieve full extraction. Or, sometimes you experience the opposite, and the IH will over-achieve and heat a vapcap to the point of combustion
before the 2nd click. It can be very frustrating, even for a guy that makes these devices.
I wanted to make the FD perform better and NOT exhibit behavior like this, so to learn more (and hopefully discover a better coil), I decided to try as many different coil configurations as I could think up, including glass and carbon fiber inserts in sizes from 13mm OD to 17mm OD (in various wall thicknesses), and coil wires in gauges from as thin as 22ga to as thick as 14ga. For reference, the standard Flux Deluxe coil wire size is 16ga. Here are a few of the ones I ran through my testing units:
It was a
very worthwhile exercise, and I learned some things, which I share below. If this were a movie, this is where we'd see the montage of me trying one coil design after another...
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...
...
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...
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...etc...
...until I inadvertently found the answer I was looking for in an unexpected place. And in truth, that
is more-or-less what happened.
Here's my big takeaway from trying a large number of different coil configurations:
Coil height height matters, and it matters a lot!
I observed best results when I heated heat the tip of the vapcap at a slightly slower rate than the body of the vapcap. To do this, I positioned the bottom loop in the FD coil above (or about equal to) the tip of the vapcap, when the vapcap is pressed into the tactile switch.
You can configure the FD to heat this way by locating the bottom loop of the coil 9mm above the PCB, as shown below.
I am am probably not the first to articulate the above concept, so consider it independent confirmation.
How does this affect the Flux deluxe? Here's the Flux Deluxe's tactile switch, with pyrex button attached:
The button top sits 8mm above the surface of the PCB.
Very early FD's had the button on a 1.5mm tall cap, for even taller initial height.
This is the Flux Deluxe coil as I have been making them to this point:
Note that the bottom loop of the coil is flush with the top of the second o-ring. (Each o-ring has a center line from its mold, so there are really only two.) This works fine, but
now...
-- [MUSIC RISES to reveal following image WITH DRAMATIC FLOURISH!] --
...it can be made to work much better (!!!) by raising the height of the bottom loop of the work coil until it sits about even with or very slightly above the height of the top of the pyrex button:
That's all it takes! Testing has shown me that this is the
ideal coil height. A vapcap (~1cm diameter) is shown at left for scale.
I have tested the CRAP out of these different coils with this device, and this is by far the biggest win to come from that testing. So far, this new coil height has improved the performance of every coil combination I have tried it with. I am making that conclusion based on the quality and quantity of the vapor being produced, as well as the quality of the extraction and color of the ABV. I will be making and posting some videos to demonstrate this as soon as I can find the time to do so.
A longer heat up time gives induction-generated heat more time to penetrate into the tip before clicking the vapcap, and this is something most of us will notice and appreciate immediately. It's an analog device, and it turns out the coil's true sweet spot is a few mm higher up than I initially thought. D'Oh!
To remedy for the future, I am increasing the number of o-rings under the coil to three, which raises the coil to the better height. I may also pull a loop from the coil to keep the overall height of things in check:
A three o-ring stack gives a better coil height, as seen above.
This is good news for news for future FD owners, obviously, but current FD owners can still take heart:
any FD can be improved with this change (!), although unfortunately not every coil has enough slack in its construction to permit it to be raised up like this. My recent coils are probably too tight for end users to adjust themselves, for example. You can certainly send it in to me, and for the cost of postage I will be
happy to adjust it for you. If you have ever been frustrated with your IH heater's performance and wish it heated a bit better, this simple way to make it heat better.
If you are currently a FD owner and want to try adjusting the coil height height on your FD yourself, you can give it a try using the instructions shown here:
https://fluxerheaters.com/faq-and-other-resources
Warning: This is a potential can of worms for some people, so don't feel you need to do this! You don't! 
The coil is simply a loop of copper wire and it will bend easily, so always move it gently. When adjusting the height of the coil, try to slide the entire coil upwards on the insert, starting from the bottom,
without breaking the insert or otherwise damaging anything! Try moving it upwards g-e-n-t-l-y, with a slight wiggling motion. If the coil seems to be too tight around the glass to move, you can try twisting the coil very gently counterclockwise to release its tension and free it enough to move. Go slow and don't be a hero. There is no need to mess with this adjustment if you like the way your FD performs now. Good luck, and please report back as folks try this.
Final thoughts, plus I eat some crow: We actually discussed coil height in this thread back in October - and earlier, too, though I could not find that post. Back in October I told
@Andreaerdna ,
@lookhigh , and some others very declaratively,
"There isn't any room to move the coil up or down. I suppose it could be possible to remove the top o-ring and move the coil up the equivalent space - 1mm at most - but that's it. "...
A statement that has aged like milk.
Here it is in full.
I'll set things straight now:
I was wrong about the impact of coil height on the performance of this device! You guys were right, and it makes a significant difference. Furthermore, when properly adjusted it definitely improves the performance of this heater. Thanks for making me aware of this parameter, and how important it is! You guys rock! 
Cheers all, and have a great weekend!
sorry.
- has confirmed that a taller coil height is the way to go for this device.
