Bypass Thermostat but keep Heat Control?

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CrazyCanadian
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Bypass Thermostat but keep Heat Control?

Post by CrazyCanadian »

Hi All

I read a bunch of topics that talk about bypassing the thermostat on a hot plate. The result is that the hot plate is 100% all the time and you have to live with that or add in another type of control for the heat.

My question is whether anyone knows how to bypass the thermostat (only to keep the hot plate from cycling on and off every 15 seconds) but still keep the ability to adjust the heat with the original control knob.

My hot plate is a Nesco 1500 watt model. If I can resize them I'll attach pics

The wiring is this

power wires come in. White goes to on/off then heating element. Red goes to heat dial. It comes back to the heat element. Another set of wires come from both heat element terminals to a power indicator light. The thermostat must be part of the heat control dial.

When the heat control dial is turned to about 1/3 power a simple screw extends and pushes a relay that clicks to disconnect from one position and connects to another. That relay either engages the thermostat that may only be necessary when the burner is on high. Or there is really only two heat selections, high and low, and the thermostat is somewhere else.

I am wondering if I disengage that relay or force it to stay one way or the other that I will bypass the thermostat but still keep heat control.

Sorry for the length of this. Let me know your thoughts.
hpby98
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Re: Bypass Thermostat but keep Heat Control?

Post by hpby98 »

Pretty sure one of these will control your element just fine, with a ssr

https://www.auberins.com/index.php?main ... cts_id=559" onclick="window.open(this.href);return false;" rel="nofollow

It senses when your column reaches temperature then drops the power to a preset level for the rest of the run

Reading your other thread regarding the PID - THIS ISNT a PID

I warm up with 4400 Watts then drop to 1100 for reflux runs. This would do it automatically for me. Definitely an upgrade I’m thinking about
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still_stirrin
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Re: Bypass Thermostat but keep Heat Control?

Post by still_stirrin »

Does your hotplate look like this one?
Nesco hotplate
Nesco hotplate
If so, the thermostat is in the knob that adjusts the temperature (on the right?). You'll have to open the hotplate up and disconnect that knob. But, in it's place you install a current regulation circuit. If you don't know what you're doing, it is probably best to enlist the help of someone who does.
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