Tuesday Tech Talk!


This Tech post is about heating-up and efficient iStill usage. About power requirements and control on (especially) our electrically fired units.

The X Factor

No, not a talent show in this case. For us, Factor X stands for an important value I use to design our iStills. It’s the value that expresses the Wattage needed to heat up one liter (for USA folk: that’s about a quart) in one hour.

Yeah, like that’s important, right?

Yes it is, because this value expresses unit efficiency. And if we know that value, we can both use it to design the correct heat-up power as well as check if a newly designed unit lives up to its expected efficiency rating. A self-imposed rating, and a very severe rating, but that’s us: our pay-off is “Distilling made easy” and to be able to do so maximizing efficiency is tremendously important.

So … what is it?

It’s 1.03. That simple. 1.03. Remember the number. I’ll explain it via an example.

An example

The iStill 500 NextGen heats up in 2 hours. During that heat-up period it uses 18 kW all the time. And since it is the iStill 500 NextGen … it of course is charged with 500 liters. Here we go:

  1. During the 2 hours the temperature changes by around 70 degrees Celsius;
  2. That takes 2 hours times 18000 Watts is a total of 36000 Watts or 36 kWh;
  3. So for 500 liters to heat up with 70 degrees Celsius, we need 36000 Watts ;
  4. If we divide 36000 by 500 liters, it turns out that heating up one liter with 70 degrees C takes just 72 Watts;
  5. One liter heats up with 70 degrees by adding 72 Watts of energy input;
  6. So if we want to heat-up 1 liter by 1 degree Celsius we need to divide 72 Watts by 70 degrees;
  7. Voila: 1,0285714;
  8. That’s close enough to 1.03 for me!

This example shows that our Factor X is 1.03. That it takes the iStill 500 NextGen 1.03 Watt to heat up one liter of wash by one degree Celsius.

Water Heater Functionality

For one of our UK customers we have build a Water Heater. An iStill 2000 NextGen that will serve them as a Water Heater, yes, that way. They will get two units actually. One iStill 2000 NextGen they will use to distill single malt whisky. The other (on the pictures underneath) will be used to collect the warm cooling water, that comes of the still, heat it up overnight, so the next day mashing a new batch can start early.

Let’s do the math!

Will you do the math with me? Because we have all night, very fast heat-up times are not needed. We have all night, right? Also, we work with a maximum of 2000 liters, since this is a 2000 liter unit. In fact, 1600 liters is more to the point, since that is the approximate amount of water needed to mash a total of 2000 liters of water and grain.

Okay, we need to heat-up 1600 liters (415 gallon) and we have got all night, so at least 12 hours. Say the cooling water is 35 degrees,  and let’s assume that we need the water to be taken 80 degrees Celsius.

Do you remember that it takes 1.03 Watt to heat up one liter by one degree. We want to heat-up 1600 liters, so it takes around 1700 Watt to heat-up 1600 liters by one degree Celsius. We don’t want to raise the temperature by 1 degree, though, but by 45 degrees. This means we actually need 45 times 1700 is 76.500 Watt or 76.5 kW.

Normally, the iStill 2000 NextGen, when fired electrically, is mounted with a 36 kW heating system. But that would be – given it’s current use as a water heater – overkill. To save costs we opted for an 18 kW power system. If we divide 76.5 kW by 18 kW, it turns out that this configuration can hit target temperature in 4 hours and 15 minutes.

More functionality

In case the UK Craft Distiller wants to heat-up at a slower pace, we offer more functionality. He can dial in different power settings. Even though the maximum power input to the water heater configuration is 18 kW, he can tune that down to 9 kW. Heat-up will now go more gentle and will take 8 hours and 30 minutes.

But what if the craft distiller stops distilling at 6 pm and only wants to start mashing at 8 am the next day? That’s a 14 hour in between time. There are two options we offer:

  1. Tune down the power input even more, for instance to 6 kW;
  2. Set the timer.

Our timer functionality is clock time based. If the craft distiller wants the water to be at strike temperature at 8 am the next day, he can also leave the unit at maximum power setting and tell it to start heating up at 3:45 am. The water will be 80 degrees Celsius at 8 o’clock. Of course, any other combination of power input and timer setting is also possible. This timer functionality is also available in our mashing, fermenting, and distilling software.

And more versatility!

We designed the iStill NextGen line-up to be ultimately versatile. The above set-up is a fine example of that: one iStill 2000 NextGen is used as a still, the other as the distillery’s main water heater. But there is more, much more versatility to be found.

Imagine this craft distiller deciding to use his water heater for distillation purposes in the future. All he has to do is order an upgraded heating system and a column …

And the same holds through for the unit that works as a still. It has an agitator, so if the craft distiller wants to use it as a masher, all he needs to do is order the boiler radiator for mash cooling …


Here are some pictures of us testing the water heater iStill 2000 NextGen unit. The program is self learning, so if we let it run a few times, it will perform better and better. The first run, it may overshoot the dialed in strike temperature by 0.6 degrees, the second run it will use new parameters and minimize overshooting to 0.4 degrees. From the third run onwards, it will easily stay within 0.3 degrees Celsius of the dialed in strik temperature.