HDtemper

[Yulsam]

 

 

I am dedicating this working chocolate tempering machine to Kerry Beal. Although I have not met Kerry nor spoken with her, I have learnt way more from her than any other source of information re chocolate making, including a three day course that cost me more than her Eztemper.

 

Note to the readers: Although this is a low cost alternative machine that works, I do not recommend it and will not give design or construction details for one simple reason. This machine, as built, comes very close to using a hair dryer in a bathtub full of water, and will never get a CSA, UL or CE certification. As an electrical engineer who has made mistakes, some of them costly, in my professional work, I know how to protect myself and those around me from the two dangers of electricity, Electrocution and Fire. 

I strongly advise you to purchase an EZtemper if your business plan or your financial situation justifies it. It is designed and built as a low voltage machine, making it is as safe and even safer than the iPhone in your pocket.

 

 I need to warm up coconut butter to a pre-established temperature around 33.5 C, and maintain it at that temperature. Since I do chocolate once a week or every two weeks, I do not want to keep the machine running, so I want a machine that will get my CB at working temperature in a few hours. I did some initial tests with CB vacuum packed in a pouch and warmed up in a sous vide water bath. It works, but it is quite messy. At the same time, I built different prototypes of chocolate melters using circulated warm water pumped from a small tank maintained at constant temperatures by my Anova. This will be the subject of a second post, and I will give full details on building the melter for about 100$ plus the cost of an Anova or similar machine.

 

I decided to use water to keep the CB warm for two reasons. Water is an excellent heat transfer medium compared to air, so the warming up process would be faster. It also has a much higher heat storage capacity, which makes it easier to to control and maintain its temperature. The machine is simply a 4 litre plastic bucket from Home Depot. Inside there is a cheap 120 V submersible water heater, a small water recirculating pump that keeps the temperature uniform inside the bucket, and two supports for 250 ml. Mason jars that keep the upper 1/3 of the jar above water level.

 

To be continued….

[Yulsam]

After more than 24 hours of continuous operation, with the cover both in place and off, the temperature stayed at 33.6C, and there were very few occasions when it would fall to 33.5C and then return to 33.6C in less than 5 seconds. Setting up the PID controller took more than the time to build the machine. The controller has an auto tune function that supposedly finds the best set of variables to control the heating to get the machine running at the preset temperature. I tried implementing it several times, but most of the time the controller would start auto tuning, and stay there indefinitely until I turned it off. On a couple of occasions it would finish tuning and switch to automatic mode, but it would oscillate around the preset temperature by about +/- 1C. With trial and error, I was able to finally find a good set of variables to maintain the preset temperature.

 

The picture shows the components inside the bucket. The submersible 120volt heater (yellow cable) is the most critical component, as it is two wire (hot and neutral) with no ground, so in case of an electric fault, the water could become electrically live. I honestly do not know how Amazon gets away with selling this stuff. I have connected a ground wire to the water, and run the machine from a gfci breaker, so it will trip in case of a fault. I also turn the heater off before I put my hand in the water.

You can also see the temperature sensor(silver color) and the blurred black circulating pump at the bottom. This is a 5volt pump, so no problem there. I have two supports for mason jars, but I will ultimately remove one, and replace it with a different support to hold up to 9 colored CB tubes.

I did a trial removing one of the jars and letting it cool down to room temperature. I put it back in the warmed up machine, and after 3 hours the CB had the consistency of soft mayonnaise. I haven’t tried tempering a batch of chocolate, but I am confident that it will work.

The mason jar is easy to wipe dry, as the cover and part of the jar are above the water line. I have been looking for a stainless steel jar with a water tight cover, which will lower the time needed to get the CB at the working temperature.

The pros of this machine:

1. The low cost of the components. For me as a retired engineer, my time is free, and the total cost is limited to that of the components. I enjoyed working on this project, and that was an additional benefit. On two consecutive nights I woke up at 3 am and went back to work. 

2. Water heats the jar and the CB in a short time, and with a suitable s/s jar, it should get even faster. That negates the need to keep the machine running continuously.

On the other hand I can think of two cons:

1. Safety: I am looking to replace the heater with a 12 or 24volt one. In that case the  120volt would not be needed at all, and the machine will use a low voltage power supply.

2. Running a water bucket for a long time at 33 degrees is calling for mold to grow in the tank. I have added bleach to a concentration of 20ppm, and  this would require testing the water regularly to maintain the chlorine level.

 

This is a work in progress, and I will keep you posted on further developments.

[Yulsam]

Update - HDtemper is dead.

 

After a few weeks of operation, the GFCI breaker tripped, so I plugged the machine in a regular outlet, and I wasn’t surprised to find the water live at 120 Volts!

As I had expected, the heater had shorted to the water, so I went back to what I should have done from the start, running everything at 12 VDC. I also replaced the plastic bucket with a double walled stainless steel tank that I found on ebay, so a 50watt heater @12V is plenty, especially if I prefill the tank with water at close to 33C.

The beta version is working beautifully, and when I set the controller at 33.5C, it maintains that temperature without even moving 0.1C. I haven’t decided on a name to replace HDtemper, readers’ suggestions are welcome.

 

 

 

I am still waiting on some stainless fixtures that I ordered to hold the different items securely inside the tank. I will make a final report with photos after I get them.