Boiler questions for fruit mashes - induction?

[VincentPrice]

Hi everyone,
I'm in the process of building my first still and I'm wondering what I can use as a boiler (~35l or 10gal). I've done quite a bit of reading but I'm not sure what exactly to do.

I mainly want to distill my own fermented fruits. So I'll be dealing with almost 100% mashes with gunk, pits, pulp, etc. in it. That to my mind means I can't really go the route with an internal element since it will burn those. Right?

I have a big game caliber 3500W induction hot plate that I got on the cheap from a friend who used to brew. That's what I plan use as a heat source.

Unfortunately that would mean I can't use the more common variants of kegs or milk cans as a boiler.

My plan so far is to look for a used cooking pot in that size, drill a hole in the lid and weld on a TC ferrule (luckily I have a friend who can weld SS). Then to use a silicone ring wrapped in PTFE tape as a gasket and tighten it down with bulldog clamps. I know silicone isn't without issues but would really like to avoid messing around with flour paste.

Is that resonable? Any other ideas how to do it? Should I ditch the induction idea entirely? I would like to keep it electric.

[Iulistoi]

I sometimes use a 36 liters stock pot on an induction stove top. Even it burns 2100W, the net heating power used is about 1400W. I think this is because the diameter of pot exceeds the recomended diameter. I don't understand where heat goes. Insulating the pot still doesn't make a difference. The bottom keeps the magnet strongly but the sides, weaker. There is 1 cm aluminium disc in the bottom. Another pot that is enameled and wider have the same heating power efficiency. The take off rate is about 2.6 liters per hour in pot still mode and this is too low.

I would advise to test the pot first before drilling it. Boil a certain volume of water, count the seconds untill boiling and aply the formula: 4200 x Volume of water x (Final temperature - Initial temperature) / Seconds = Watts used.

Don't forget that induction, after internal element, is the most efficient heating source, with up to 90% efficiency. Electric stove top is about 74% efficient and gass only 40%. So if you have low efficiency on induction plate may be due to the pot (not very magnetic or too wide).

[SmokyMtn]

Electric has never been of any interest to me. Not saying it doesn't have its place. Here is an alternative if you need one.

https://homedistiller.org/forum/viewtop ... 16&t=79361

[VincentPrice]

I would advise to test the pot first before drilling it. Boil a certain volume of water, count the seconds untill boiling and aply the formula: 4200 x Volume of water x (Final temperature - Initial temperature) / Seconds = Watts used.

Thanks. But I'm not too concerned about not having enough power. As I said it's a pretty hefty hot plate with 3500W. I was looking for general advice whether my assumption is correct that I should go with an external heat source and if so whether just buying a big cooking pot and going from there is the right way to go.

[EricTheRed]

Have you thought about getting 2 pots - one fitted into the other and using indirect heat? ie: Get a 50 Litre pot and insert a 30 litre pot with your wash/mash - and fill the large pot with water
Double boiler style - not chance of scorching, burning etc.
You would have to heat slowly though otherwise you would boil some of the water away before the real process starts in the smaller pot

[Saltbush Bill]

Get a 50 Litre pot and insert a 30 litre pot with your wash/mash - and fill the large pot with water
Double boiler style - not chance of scorching, burning etc.

If it were that easy the idea would be used more, search around a bit and you will find no-one does it that way, people uses steam or oils instead.

[EricTheRed]

Saltbush Bill - even with the large pot being the still itself? with the smaller pot inside of it? ie: everything heats up? works with cooking so why not for this?
Curiosity on my part

[NormandieStill]

I think it's a temperature differential problem. When you're melting chocolate or cooking gently, you're not aiming for high (100C) temperatures. When distilling you want to keep putting energy in efficiently and when your wash is at 90C (for example) and your water bath is at 95C (because you're going to struggle to hold it at 100C especially with boil-off) you're going to have minimal energy transfer from the jacket to the wash.

Edit to add: also you're going to be distilling in a steam room and continuously topping up the outer pot (which will cool the water slightly and reduce your energy transfer into the wash)

[EricTheRed]

Got it
Thanks

[subbrew]

Normandie is correct. you just can't get enough temp differential will 100C water trying to heat your mash to 82C or higher. Without the temp differential you don't get the heat flow. Vincent - I suggest using a double boiler with oil. I use it on my small still. Depending on what I am doing oil temps range from 220F to 250F. So no worry about smoking the oil. You might go a bit higher if you are doing a stripping run but I am condenser limited so that is the temps I see. The draw back is slow response to changes in heat input.

Of course if you can build or afford it a steam jacketed or steam injection boiler would be even better as it would offer better heat control with fast response. But then you are dealing with low pressure steam which has its own maintenance issues. (scale, relief valve testing, some serious burn risk if you don't know what you are doing..)