Marble tile as heat spreader for hotplate?

p_su · Post by **p_su** » Mon Dec 17, 2007 10:55 am

I think the subject says it all. I've got a hot plate that cycles on and off - not good for a column reflux. I've read that using a head spreader like plate steel or a cast iron pan helps even things out. I've got some marble tiles 12"x12"x1/4" laying around - and I was wondering if anyone knew if that would work? I only found a few mentions of people heating marble - one from this site: AllExperts

"You can heat up marble to temperatures up to 300 degrees C or 572 degrees F"

And a little snippet from wikipedia:
"Ground calcium carbonate is used in plastics because it imparts stiffness, impact strength, dimensional stability, and thermal conductivity."

I have been looking around for a source of plate steel or a cast iron pan large enough to accommodate my 20qt pot - but so far no luck. It won't conduct as well as metal I'm sure, but it's primary function as a spreader seems to be to even out the flow of heat and act as a sort of 'heat reservoir' for when the hotplate clicks off. Any thoughts?
Thanks all.

junkyard dawg · Post by **junkyard dawg** » Mon Dec 17, 2007 11:07 am

why not just get propane? I wouldn't think that marble will help too much.

Post by **bronzdragon** » Mon Dec 17, 2007 11:20 am

I have the same problem. I believe that the tile would absorb too much of the heat. I am having good luck using aluminum flashing. I got a small roll at the hardware near the gutter supplies. I cut three squares big enough to fit under the pot and over the burner and just put them together and the pot on top.

It spreads the heat nicely without absorbing too much heat. These will not last forever, but I've been using them for several sessions and they seem to be a good stop-gap measure. The aluminum heat dispersion plate that came with mine was just too thick and absorbing too much of the heat.

The flashing does have a bit of a oily coating that takes about 20 minutes to burn off ... but there was no harm done, other then a stink in the air for awhile.

Sure wish I could use propane, but that's not going to work around here.

~r~

p_su · Post by **p_su** » Mon Dec 17, 2007 11:34 am

junkyard - I would go to propane - but it is not an option for me where I am now. I must keep indoors - and am leery of using a large propane burner in my particular living situation.

Bronz - thanks for the tip. I will check that out - I was hoping to find a thicker material, but maybe a few layers of a thinner one would work. I thought that the many layers would have air gaps which would make them poor at insulating...? Do they sit pretty flat?

Post by **bronzdragon** » Mon Dec 17, 2007 11:42 am

The layers warp with use. It's not a permanent fix, just something until I can figure out a better option.

~r~

byacey · Post by **byacey** » Mon Dec 17, 2007 4:44 pm

The marble will probably crack from thermal stress. It shouldn't be too hard to find a piece of plate iron at the scrap yards.

BW Redneck · Post by **BW Redneck** » Mon Dec 17, 2007 5:42 pm

I agree with ya there, byacey. A plate of scrap iron shouldn't be too hard to find in a junkyard. I have too much experience with hot rocks splintering. One put a nice scratch in my glasses lens. Reminder for safety glasses everyone!

p_su · Post by **p_su** » Mon Dec 17, 2007 5:54 pm

Thanks for the comments all. Well.. to a point there is no way to know but to try. I heated up 2 quarts of water through the tile - it was slow going. The stone holds a TON of heat - water would still sizzle off of it even after it was off the hotplate for 20min. I need something that will conduct heat a bit faster - stone is too slow. It did crack slightly twice, along some obvious stress points in the marble pattern, but didn't split through -- cracks only went about 1" long or so.

Believe me - if there were any useful scrapyards/junkyards around... I'd be there. All the places I've found recycle scrap - and do not sell. Must be some fluke of location...

junkyard dawg · Post by **junkyard dawg** » Mon Dec 17, 2007 6:05 pm

build you a controller. There are detailed plans in sticky...

goose eye · Post by **goose eye** » Tue Dec 18, 2007 4:09 am

dont no nothin bout the way you cookin but you lookin
castiron get you a skillet or dutch oven. can get em from farm suply
store. make sure you keep it cured an you can cook you up a mess
of cornbread an such

dr_gribb · Post by **dr_gribb** » Tue Dec 18, 2007 10:57 am

I have a all glass reflux still with a 5L glass boiler, that i run on my kitchen stove. The glass boiler sits in a cast iron bowl filled with sandblower sand.

Its very slow to react to heat changes, but runs fine after stabilizing. I preheat the sand in the oven and this give me a 35 min time to boil up 3L mash.

defcon4 · Post by **defcon4** » Tue Dec 18, 2007 11:02 am

junkyard dawg wrote:build you a controller. There are detailed plans in sticky...

Couldn't agree more, I had the same problem with my electric hotplate. If you build pintoshine's heating element control, you can control your electric element just as well as you can control propane. See the sticky on "heating element control".

p_su · Post by **p_su** » Tue Dec 18, 2007 11:23 am

I'll look into the heat control - just was hoping to find some $3 solution that only requires setting something under the pot...

If i made the controller wouldn't I have to bypass the internal switch for the hotplate?

defcon4 · Post by **defcon4** » Tue Dec 18, 2007 7:26 pm

p_su wrote:I'll look into the heat control - just was hoping to find some $3 solution that only requires setting something under the pot... If i made the controller wouldn't I have to bypass the internal switch for the hotplate?

No, just leave the hotplate switch on full blast, the heating element control described in that thread will control the hotplate perfectly (ie, no switching on/off on/off on/off, it will just adjust the amount of power sent to the heating element and act like a dimmer switch (but don't just wire a dimmer switch to the element, read the thread on heating element control)

This heating element control is kind of like a "$3" solution but I spent more like $20 on the parts and put it together in 1-2hrs. Pintoshine even sells a kit for 220V systems.

dixiedrifter · Post by **dixiedrifter** » Sat Dec 22, 2007 1:16 am

Most laboratory mantle controllers are of the triac design (meaning they alter the timing of the current from what I understand) rather than a variac which alters the voltage.

One should be able to pick up a harbor freight router speed controller for cheap.. IIRC its good to 10+ amps.

And, for better heat transfer, use some glass cloth available in the fiberglass supplies dept of most auto and hardware stores.

defcon4 · Post by **defcon4** » Sat Dec 22, 2007 5:21 am

dixiedrifter wrote:Most laboratory mantle controllers are of the triac design (meaning they alter the timing of the current from what I understand) rather than a variac which alters the voltage.

One should be able to pick up a harbor freight router speed controller for cheap.. IIRC its good to 10+ amps.

And, for better heat transfer, use some glass cloth available in the fiberglass supplies dept of most auto and hardware stores.

A router speed controller won't work for controlling a heating element, this has all been covered already in the "Heating Element Control" thread, do a search.

Mr Clean · Post by **Mr Clean** » Fri Mar 06, 2009 7:18 am

anyone familiar with hotplates in excess of 1500 watts? I'm looking to increase my heat input and have 240 v available, like the hotplate because it runs pretty good in my situation, minimal monitoring, other solution would be to go to gas but I'd rather not. The propane burners used for turkey fryers, etc. can be converted to natural gas, I would assume but have no idea how to do that, smaller or larger orifice?

Thanks in advance

Ugly · Post by **Ugly** » Fri Mar 06, 2009 8:15 pm

NG regulators are cheap and often used on BBQ's directly hooked up to NG supplies. If the propane regulator is a serviceable model (most are disposable) it's usually a matter of a small conversion kit with a few plates and springs. I've salvaged a few NG and converted them to propane (other way around for me - man I love the dump)

Building a 240v control is relatively easy, use the diagrams posted here and order your own parts, or order a kit (very complete) from pintoshine's site. I've used a similar design of my own for ten years and my keg controller is 9. I'm just slapping together a new 240 controller myself for another still.

Post by **myles** » Thu Mar 12, 2009 6:56 am

The Pinto controller is the way to go - or a simmilar alternative. I wanted to put 3 small cooker rings under a pot. Sort of clover leaf patern. At 1500 watts each that's 4500 watts. However, at 240v that works out at 18.75 amps.

Well within the capacity of the controller, but not for the domestic circuit. You really want to put in a dedicated circuit for the boiler expecially if you are going for an extreme rig with for example a couple of 5kW elements.

10kW at 240v is close to 42 Amps. And I don't know because I never asked - do you get power spikes with these triac controllers?

Ugly · Post by **Ugly** » Thu Mar 12, 2009 11:53 am

A power spike can come through since the controllers are unregulated, but not because of the controller (will you get a spike)...

A whole house passive surge clamping system is basically a series of capacitors running between the three incoming lines (120, 120, neutral in North America) and can be easily made and installed with a little research. Might save the elements in your fridge (frost free uses element to thaw ice build) and oven sometime. Getting a surge in an immersion element is usually not that big a deal since they are cooled all over their entire surface by being submersed.

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Marble tile as heat spreader for hotplate?

Marble tile as heat spreader for hotplate?

sandbath

high watt hotplate?

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Re: Marble tile as heat spreader for hotplate?

Re: Marble tile as heat spreader for hotplate?