Thoughts on this temp controller for cm

[notshy]

G'day guys,

First post here, I'm trying to help my old man out with a reflux cm still. I know most of you are probably cringing but he's happy with it so we'll leave it at that! The boiling process is done with a large 40ltr urn and once it is up to temp the urn temperature control turns off and is very slow to start again. I am thinking of hardwiring this programmable controller (http://www.jbbrewsupplies.com.au/shop/v ... roductid=5" onclick="window.open(this.href);return false;" rel="nofollow) into the urn circuit and having a sensor up at the take off point where the temp needs to be read. In my eyes this will atleast make the heating more acurate and then work on the cooling side of things, as it is very dificult to juggle settings as many people have also stated on the forum.
BTW he averages 85%
Any ideas would be great cheers?

[mrhooch]

Notshy:

You say urn, like it is a coffee urn or something like that.

If it is, then there is another thermostatic control somewhere in the bottom. Keeps the coffee from getting too hot and getting that burnt taste. It plays hell when you are trying to distill though. I had a similar problem with my coffee maker still, had to bypass it until I got a higher temp version of it. It was rated at 195.

If you aren't sure what it looks like, take a picture of the innards, I'll point out the part that is likely to be causing the issue.

Hooch.

[notshy]

Boils 40 liters of water and keeps set temp doesn't just heat, for coffee or tea. There is a controller at the bottom but it switches the element very slowly and defines the temp of wash at the bottom end of the operation. I have the idea that if the element was switched quicker and regulated by measuring the temp from the top of the column it would be easier to control everything. Because there is such a big difference in temp between the bottom of the still and the top of the column it is hard to control.

[mrhooch]

Yup, there is a safety thermostat in there somewhere which is shutting it down. When they get older, they get more sensitive and shut off quicker and quicker.

Hooch.

[rad14701]

Greetings, notshy...

You really need a phase angle or burst fire controller rather than a programmable thermostat... The controller that link points to will not adequately maintain a constant temperature... If you can bypass the thermostats in the coffer urn you can power it with a triac based controller as mentioned elsewhere in these forums... Another option is using a United Automation PSR-25 and a potentiometer which will cost in the range of $50 USD for all parts except an aluminum heat sink and a project box... Do a site search or Google search for United Automation PSR-25 for more information...

[notshy]

Sorry I realise this has been thrashed to death in another post, BUT......

The guy selling these ensures they are programmable to within 1 deg c which would be ideal I thought. Unless the element wont handle that ferocious switching The element is a 2400 watt which is too big for a triac and dimmer circut I gather from other posts. Anyone else here in Australia has over come this problem and has a similar set up I would be interested to here how they did it? A problem I am having is that alot of the links in other posts to gear that people have bought for controllers have been out of date and disappeared. I am a sparky so I can follow diagrams but parts are hard to come by where I am and would like to get a prebuilt unit, but any info will help.

[mrhooch]

Notshy:

That controller will work if:

1) It uses a triac to provide adjustable power to the element, not just a bang bang controller.
2) If you want to mount the thermal sensor in the top of the column, you need a PID controller. They learn and can handle the long delay between action (element on) to reaction (change in temp in the column).

If you want super easy, just mount a big MF diode in series with the element. It will reduce the power to the element by 1/2 giving you 1200 watts, not a bad number to distill at. If you mount a switch across the diode, you can heat up at 2400, then open the switch and run at 1200.

Hooch.