Heating Element Controlled By A Pid - Current Draw Once At Temp

[JPAT]

You cant use PWM to control a solid state relay (SSR).

We use PWM over SSRs to control heaters varies voltage 50-230

 

[QldKev]

What if you put the dimmer on the HLT circuit.
Initially allow 100% load to get up to temp.
BEFORE you mash in, turn the dimmer to 50% ie 1100w
The PID on the Heat exchanger will always have the full 2200w element behind it.
....
maybe a bit dangerous if you forget to set the dimmer.




I like booargy's way with the relay.
Initially the HLT gets the 2200w until you mash in
When you enable the Heat exchanger the PID controlls it with the full power.
When the PID isn't using the power, the HLT can have it, if the controller wants it.

As long as the HX doesn't steal too much time on the power and the HLT gets enough time to get the water hot enough by the end of mashing.



the only other alternative I can think off is the way method I said initially
have a 2200w and a 1000w element in the HLT.
Run the HLT controller on the 2200w to get to temp, and then swap it over for the smaller element.
OR
Run the HLT controller on the 1000w element, and use the 2200w without the controller to get you close to the temp, then swap over the power from the 2200w to the HX.

Then the PID has the full 2200w for the HX,
and the HLT can use the 1000w to play at 100% of the time.



QldKev

 

[JaseH]

Its probably too obvious to not have considered it already, but do you have a standard 10amp outlet available as well as your 15amp? I run my rig off 2 circuits a 10 and 15 to get around overloading a single circuit.

 

[kjparker]

Its probably too obvious to not have considered it already, but do you have a standard 10amp outlet available as well as your 15amp? I run my rig off 2 circuits a 10 and 15 to get around overloading a single circuit.

Unfortunately not.

In my shed, the einstein who wired it up used a 16amp main breaker for it.

I had considered having the breakers upgraded, as the cable is 4mm so upping to to 25a would be perfectly safe.... but for now I got to work with what I have....

yes it would.


perhaps using the dimmer directly in line and removing pid control from the boil, thus the pid would self tune to always switching the lower (dimmed) wattage.

PID wont have anything to do with the boil, the boil wont be happening in any of these vessels either! Once the mash is done, it will be moved to the kettle for the boil, which will end up with a 15amp element in it.

 

[QldKev]

I still don't get why you don't want to swap over plugs during the brewday?

Use the houses 10amp for the HERMS

Use the 16amp to run the HLT, and swap over the cable to the kettle when needed.

 

[kjparker]

I still don't get why you don't want to swap over plugs during the brewday?

Use the houses 10amp for the HERMS

Use the 16amp to run the HLT, and swap over the cable to the kettle when needed.

In a word.. Convenience.

If I can get away with not running the monster extension lead from the house to the shed I will.....

 

[mILLrAT]

We use PWM over SSRs to control heaters varies voltage 50-230

Another day and I have learn't something new, thanks for that. I hooked up a SSR this morning and plugged in the multimeter, changing pins to a PWM pin helped and as advertised it gave a proportional control.

I still think a software implementation that uses one or two seconds as the cycle time will have fewer on/offs for the SSR than using PWM, the more on/offs the more heat to be dissipated. But if it works then it works!

 

[kjparker]

Another day and I have learn't something new, thanks for that. I hooked up a SSR this morning and plugged in the multimeter, changing pins to a PWM pin helped and as advertised it gave a proportional control.

I still think a software implementation that uses one or two seconds as the cycle time will have fewer on/offs for the SSR than using PWM, the more on/offs the more heat to be dissipated. But if it works then it works!

What pid were you using?

 

[mILLrAT]

What pid were you using?

I was playing with a PID loop hooked up to a paint stripper heat gun controlled using a thermocouple used for roasting coffee beans, the following link has code and references etc

http://www.arduino.cc/playground/Code/PIDLibrary