Controlling a hotplate questions

[MtRainier]

I bought the StillDragon controller kit and built it into a 120V 15A extension cord.

I'm using that to control a 1500W Nesco hotplate: http://a.co/d/b5EuP8j" onclick="window.open(this.href);return false;" rel="nofollow which I opened up and shorted out the internal heat control. It's a really simple hotplate with just two wires on the heat control knob that I clipped and connected together. Then I just plug it into the extension cord which has the controller wired on to the hot conductor.

My goal was to have something to put my 12qt boiler on that I can use to get fine control on the heat for doing small pot still batches of gin infusions.

It does seem to work, but has some quirks which I'm hoping someone here who has used one of those kits or modified a hotplate can tell me if they're normal.

First is that it is noisy. The variable SSR they use seems to put an alarming amount audible hum into the hotplate. Much more than if it's plugged in to the wall. The wall power only gives it a light buzz. I know that the way variable SSR's work is to chop out part of the sine wave, but I guess I didn't expect so much noise out of it.

Second is that the 500k potentiometer only controls it from 50% up to 100%. It doesn't control over the entire range of the pot. On the meter it shows a fairly even resistance from 0 up to 500k, so I don't think it's a bad pot.

Lastly is that the entire stainless case of the burner gets pretty hot, not just the cast iron cooking surface. I guess I shouldn't be too surprised by that, because it isn't thermally isolated fro the cooking surface, but it surprised me how hot the entire thing got. I had wire-nutted the power wires together when I snipped out the thermostat, but am rethinking the yellow plastic wirenut inside the case.

Do those things seem pretty normal to those who have used SSR controlled hotplates and maybe the stilldragon controller before?

Thanks

[fizzix]

Buzzing can happen even on a full bore open hot plate coil if it's not seated tightly in its connection points.
That goes for the wiring to the connection posts themselves, too.
Does it do it with weight on the plate?
I use ceramic wire nuts anytime I see thermally sheathed wiring (that white "cloth" covering on the wires.)

I cannot explain the 50% minimum duty cycle. I think a call to Still Dragon is in order.
Since it is a kit, I doubt they put a "wrong" logarithmic pot in by mistake. (Should be, and likely is, a linear pot.)

By the way, the plastic feet on my hotplates always melt down to stubs. Yes that mutha gets HOT!

[MtRainier]

Thanks for the advice. I'll do a bit more measuring on this pot and will contact them.

It does make the noise with a full pot of water on it too. It's weird.

I'll get some ceramic wire nuts. Didn't even know they were a thing.

[StillerBoy]

Second is that the 500k potentiometer only controls it from 50% up to 100%. It doesn't control over the entire range of the pot. On the meter it shows a fairly even resistance from 0 up to 500k, so I don't think it's a bad pot.

On the controllers that I have built, I used 470K potentiometer for the main and a 47K for the fine tuner, and both do not engage until the half way mark.. and I have build over eight controller using the same pots.. but there always some power going through them even when on the off position, at least on all the pots I have tested..

Yah.. those table top stove can get pretty hot, especially with a large pot that is larger than the plate itself.. that was the main reason I installed a 120v 2000w element on my 12 qt pot..

Mars

[MtRainier]

OK. So none of the ones you've built start to fire the SSVR until 50% or around 240k ohms?

Maybe the next one I build will use this:

https://www.auberins.com/index.php?main ... cts_id=444" onclick="window.open(this.href);return false;" rel="nofollow

and a regular SSR.

[sambedded]

500K potentiometer is good for 240v. Since you are using it at 120v you need a 250K or 220K potentiometer.

[bronctoad]

I ran into the same problem with the SSR and pot from a different source.
if you look at your SSR on the control side does it say "500k ohm/ 1/4w" or
like the one I got "470-560kohm" my pot only works on the top half
from half to zero is nothing, and its very touchy in its control range
worth a look?
bronc

[sambedded]

my pot only works on the top half from half to zero is nothing, and its very touchy in its control range

Are you using it with 120 Volt heater? If so you need 200-250KOhm . Or you connect 2 pots in a series one around 500K(+- 15%) another around 50 K (+- 15%). This way you can use it conveniently at any voltage.

[MtRainier]

Had no idea it worked that way. I'll put a 250 in there then. I am indeed using it with 120V.

[sambedded]

I'd recommend 2 watt pots. Like this - https://www.ebay.com/itm/US-Stock-2x-22 ... 1736091861" onclick="window.open(this.href);return false;" rel="nofollow

Smaller wattage pots won't last long.

[MtRainier]

I use ceramic wire nuts anytime I see thermally sheathed wiring (that white "cloth" covering on the wires.)

Good call on this. I was running a second one this morning, because why not, and sparks started popping out of the inside of the plate.

Turns out the plastic wirenut melted. I should take fizzix's advice more often.

[NineInchNails]

MtRainier, have you considered installing a 110V heating element inside your boiler instead of trying to control a hotplate? There are a lot of nifty ways of installing a fitting through the side of a boiler for a heating element.

[still_stirrin]

...the entire stainless case of the burner gets pretty hot, not just the cast iron cooking surface. I guess I shouldn't be too surprised by that, because it isn't thermally isolated fro the cooking surface, but it surprised me how hot the entire thing got...

Yes, as you’ve noted...stainless steel will conduct heat, especially when you’re runing it at full power for an extended period of time.

On my Cadco hot plate, I added fiberglass insulation to help isolate the heat from the electrical controls. It keeps the heat “focused” under the heat element, so it heats the stock pot, not the housing. I bought a roll of pipe insulation...3-4” wide with an aluminum foil backing...and taped it in place using HVAC aluminum “duct” tape. Got the materials at the local big box store...you have them there too.

Also, I put the wire inside some glass woven wire sheaths, like the wires in your home oven. I got the sheath from a local surplus sales store (I enjoy going there and just looking for “stuff I don’t need”).

But most importantly, I installed a small (2” diameter) 110VAC fan (switched in the circuit) to move air through the housing, hopefully to push the warm air out of the louvers in the housing. I ordered the fan from an Amazon store for $7, or so.

These measures do reduce temperature build-up in the stainless housing, although the little fan is noisy (it whines & whistles at me to let me know I’m making gin ;-}).
ss

[MtRainier]

MtRainier, have you considered installing a 110V heating element inside your boiler instead of trying to control a hotplate? There are a lot of nifty ways of installing a fitting through the side of a boiler for a heating element.

I have one of those, but my boiler (the 3 gallon milk can from mile hi) needs 1.5 gallons of liquid to keep the element submerged. It's like halfway up the can. Not a great design. This seemed easier for the small quantities I wanted to heat while making gin.

[NineInchNails]

MtRainier, have you considered installing a 110V heating element inside your boiler instead of trying to control a hotplate? There are a lot of nifty ways of installing a fitting through the side of a boiler for a heating element.

I have one of those, but my boiler (the 3 gallon milk can from mile hi) needs 1.5 gallons of liquid to keep the element submerged. It's like halfway up the can. Not a great design. This seemed easier for the small quantities I wanted to heat while making gin.

I hear ya, but technically you could install it as low as you need to and make it a good design in comparison to Mile Hi.

A small boiler vs a large boiler shouldn't make any difference. A small boiler can have the element low just as keg boilers have their element low.

[MtRainier]

MtRainier, have you considered installing a 110V heating element inside your boiler instead of trying to control a hotplate? There are a lot of nifty ways of installing a fitting through the side of a boiler for a heating element.

I have one of those, but my boiler (the 3 gallon milk can from mile hi) needs 1.5 gallons of liquid to keep the element submerged. It's like halfway up the can. Not a great design. This seemed easier for the small quantities I wanted to heat while making gin.

I hear ya, but technically you could install it as low as you need to and make it a good design in comparison to Mile Hi.

A small boiler vs a large boiler shouldn't make any difference. A small boiler can have the element low just as keg boilers have their element low.

True, I'm no welder, but I could get one of the guys at work to put another 2" flange on it so it can go in there basically touching the bottom, but I now like the external heat solution. It lets me keep the botanicals in the liquid when running gin which an inserted heater would not. I don't know if it has a taste advantage, but it's a speed advantage (less steeping time). One big disadvantage of the hotplate is that it holds a LOT of heat, so any power changes happen with a ton of lag. Way way more than an ultra-low density element in the kettle. Honestly, given how much heat the cast iron plate holds it's possible that I didn't need to add a controller at all. I bet that mass of iron would even out the cycling on and off and might have worked just fine with the regular thermostat. Maybe not, though.

Funny thing about this little Mile Hi boiler is that their 16 gallon one has the element flange basically touching the bottom. It's much lower than their 3 gallon one. It also only takes about 1.5 gallons to submerge the element.

[MtRainier]

Well, moving on to a new plan.

The Nesco hotplate apparently had a thermal safety fuse in it which tripped, so now it's a paperweight unless I rewire it all with the fabric covered wire, lol.

Maybe I'll get one of these cruddy little stills from amazon for macerated gin. This one apparently runs on an induction cook top, which I already have and which allows you to set the power in 200W increments.

http://a.co/d/eZvDcAg" onclick="window.open(this.href);return false;" rel="nofollow

[NZChris]

A saucepan and steamer would cost a lot less, have a large gin basket and make better gin. Mine cost me a few dollars at a charity shop, a few more at the plumbing supplies and used an existing condenser. Having to make flour paste seals might be inconvenient, but it is easy and it is better than the silicone seals that come with that shiny POS that you are looking at.

[NZChris]

You may find that your paperweight comes alive again when it cools down. If you use a controller to keep the power down below where it trips, it may not cut out at the Watts you need to run a gin. Having a longer heat up time probably makes better gin anyway.

[MtRainier]

A saucepan and steamer would cost a lot less, have a large gin basket and make better gin. Mine cost me a few dollars at a charity shop, a few more at the plumbing supplies and used an existing condenser. Having to make flour paste seals might be inconvenient, but it is easy and it is better than the silicone seals that come with that shiny POS that you are looking at.

Never thought of a steamer pan as a gin basket still. That's a great idea and would just leave me with a lid to fabricate.

[MtRainier]

I decided to just try my little 3g MileHi boiler on my portable induction cooker. The darn thing isn't magnetic so I assumed it wouldn't work, but it heats just fine on it. I ran a 2L batch of Odin's Easy Gin today (modified to add 2 grams of hops per liter as well), and it came out great.