Melting chocolate is a challenge that many chocolate makers face and having a supply of melted chocolate on hand - at a known and precise temperature - is very handy.
The fastest way to do this is to use a special-purpose chocolate melter. These can cost tens of thousands of dollars. Less expensive is to use warming (or bread proofing) cabinets (without the water, of course). While these can be found used on eBay and elsewhere, new ones will set you back a thousand dollars or more and they are the size of a large speed rack - and not all kitchens have that amount of space.
Tabletop melters like the ones from Mol d'Art and Bakon tend to be comparatively expensive (a 20kg machine can easily cost close to $1000), but many people like the table-top form factor. I do, too, in part because you can mix and match pan sizes. Full, half, thirds - depending on the amount of chocolate you need to work with.
There are lots of DIY solutions, but not a whole lot that require zero construction.
A while ago, ChocolateLife member Ben Rasmussen, the founder of Potomac Chocolate, pointed me to an inexpensive buffet warmer from APW Wyott (link is to WebRestaurantStore where they are priced at $99) that he was using as a chocolate melter. I recommended this to someone else, but even on the lowest setting, they were finding that the warmer was scorching their chocolate. This is because the temperature dial isn't calibrated in degrees - it just runs from 1-10 - and, food warmers are typically designed to keep food at a minimum of 140F for food safety reasons.
NOTE: It's important that you get a unit that is designed to be used without water. Not all of them are. There are less expensive warmers than these but, as near as I can tell, they require water to work.
To combat the problem of overheating and scorching - and to provide a true temperature control - what's needed is an inexpensive sous-vide controller. (There are other temperature controllers, but you want one that's designed to work with food.) There's one on Amazon from a company called DorkFood for $99. The DorkFood sous vide controller has a range of 32F-200F with a precision of +/- 0.25 degrees.
Your "work" will be to find the maximum heat setting for the warmer that heats the chocolate without overheating and scorching it. Put the chocolate in the warmer, plug the warmer into the sous vide controller, and plug the sous vide controller into the wall, and set the temperature you are looking for.
Which means you might also be able to use the combination as a replacement for a Mol d'Art melter.
If you are having problems with the lower settings of the melter being too high, you may want to look into some sort of thermal mass (or, you could contact the manufacturer and ask). A Fibrament (or similar) baking stone will even out the heat. This may limit you to using shallower pans in the melter. Note - the smallest rectangular stone from Fibrament is bigger than the interior dimensions of the melter. Fibrament will cut to fit if you send them the dimensions with your order.
The nice thing about the sous vide controller is that it could have other applications for controlling temperature around the kitchen.
I am using a similar setup to this, and can report my experiences.
1) Thanks for the link to the buffet warmer that doesn't need water. My current system uses a water bath. This has not been a problem, since the temperature is low enough that there is not major steam production. But it is inconvenient and does risk water getting into the chocolate.
2) Rather than using one of the pre-built systems, I cobbled together a unit consisting of a Fuji PID temperature controller, external solid state relay, a plug, a receptacle, and an aluminium box. The pre-assembled units look much better for the application, but were not available at the time.
3) I find that I use one software feature of the temperature controller that I bought which is not present in the DorkFood controller. When I was programming the system, I found that I used the output percentage limit, which limits the maximum duty cycle of the heater. This effectively reduces the power rating of the heater and leads to slower heatup but much less risk of burning. (When you consider the number of melters that use 100W lightbulbs, you can see the risk of a 1500W buffet warmer....)
4) One benefit of working with the intermediate water bath is that I can regulate the temperature of the water to transfer heat to the chocolate. In the ideal system you would actually have dual PID controllers; one controller would regulate the temperature of the chocolate by calling for a particular water temperature, and the other controller would bring the temperature of the water to that target. I do not have such a setup, but perhaps one could use a dry warmer to control the temperature of an intermediate thermal mass (such as an aluminium plate).
Yeah, it's a problem with some warmers, they want to get the heater to max temp which can scorch the chocolate. So being able to set the output percentage limit is very helpful.
The dual PID controller is a good idea, too. I will have to keep that in mind.
Do you have part numbers for your Fuji PID controller and external solid state relay? And what are you using for temperature probes?
Can you post photos? I am sure ChocolateLife members are interested in seeing what you've put together.
I used a Fuji PXR3 unit. I do not recall the exact ordering code; the full part number describes the inputs and outputs. The unit that I ordered was set up for thermocouple input and SSR output.
The solid state relay was a Crydom D2425. Both were purchased from an Ebay seller who offered a bunch of them, but it appears that they have not been active since 2011.
I see a huge number of cheap PID controllers on Ebay and Amazon, but it is not clear if they have the output percentage control capability.
I may be able to get some photos in the future.
Here are a couple of photos. First the unit opened to see the inside.
You have two power cords, each with a white, a black and a green. One cord has a normal male end, the other has a female end.
The green wires go to the box, for grounding.
The white wires are spliced together along with a pigtail that goes to power the control unit.
The incoming black wire goes to a switch, and then from the switch you go to the relay and to power the control unit.
The outgoing black wire goes to the other large relay terminal.
The relay itself is mounted directly to the box to dissipate heat.
The two thermocouple leads go to the sensor input on the control box.
For the temperature probe I am using a cheap and standard plastic coated type K thermocouple. I am measuring the temperature of the water batch, not the chocolate.
Two control leads go from the control box to the relay.
Here is the unit 'plugged in':
If I have time, I would like to alter the system with the dual regulation described previously, with the heater controlling the water bath temperature, and the water bath temperature being selected to control the chocolate temperature. I'd also bag the water somehow :)
Hi Mac. Can you post a link to the controller you use?
That must be the Elitech STC 1000. Very solid device, use it to control most of my chocolate melting apparatus. Should be ~20$ on eBay.