Anybody else scorch wort with a RIMS element?

[Brewer Gerard]

i'm running a 3800W camco element on 240V in my keggle which i have use for step mashes also. Anyhow, sometimes i think it can have a bit too much power when i have grain in and only for the fact that i tend to stand over it and stir continuously i think i would probably be experiencing a bit a scorch.

My question is has anybody tried to employ a power potentiometer in this situation to reduce the amount of current being passed to the element and if so what type/model?

 

[mattd2]

...My question is has anybody tried to employ a power potentiometer in this situation to reduce the amount of current being passed to the element and if so what type/model?

A simple way to reduce the power of the element would be to run it at 110V, this would give you 1/4 of the 240V power, so yours would be 950W. Only problem is I don't know if that is enough power for you.

 

[Brewer Gerard]

A simple way to reduce the power of the element would be to run it at 110V, this would give you 1/4 of the 240V power, so yours would be 950W. Only problem is I don't know if that is enough power for you.

Yup thought of that alright, didn't actually know that switching down would reduce power by 75%. Thats a lot. Too much to be honest. What i had in mind was a dimmer switch on a light kind of thing, just one that could handle around 20A

 

[Walker]

Yup thought of that alright, didn't actually know that switching down would reduce power by 75%. Thats a lot. Too much to be honest. What i had in mind was a dimmer switch on a light kind of thing, just one that could handle around 20A

I think such things exist, but cost several hundred dollars.

That's why people use PIDs and SSRs and PWMs.

 

[shushikiary]

Yea the best solution is an SSR with PWM. Cheapest, uses less power than a dimmer, less heat wasted, and usually more accurate.

 

[Brewer Gerard]

I think such things exist, but cost several hundred dollars.

That's why people use PIDs and SSRs and PWMs.

Can you guys recommend some hardware to do such things for my keggle so. Does PWM refer to pulse width modulation to control the SSR? Sorry for the dense questions

 

[Walker]

Yes. PWM = Pulse Width Modulator. Rapidly turnning on/off the SSR with adustable amount of on vs off to effectively give you control over the amount of power.

I built my own PWM with a few dollars worth of electronics parts and a soldering iron, but I think there are kits out there that you can get for like $10 instead of doing it the hard way like I did for $5.

 

[Brewer Gerard]

Sorry Walker i just dont get how it all goes together. The way i thought it would have worked is you buy an off the shelf PID that has output terminals going directly to an SSR. Can you elaborate a bit on overall circuit layout and what type PID you have used, cheers

 

[Walker]

gerry... PID and PWM are not one in the same. Some PIDs support a PWM mode in addition to the normal PID mode, so you can indeed just wire up the PID to the SSR if it supports that kind of PWM behavior.

I built a stand-alone PWM to drive the SSR. A couple capacitors and diodes, a small 555 timer chip, and a potentiometer.

 

[thelorax121]

This seems like an elegant solution that I saw on the "Rims for Dummies" thread (page 81 of thread) -There is no heating element in the pipe. It's basically an external version of a HERMS system.

He wraps the outside of the pipe with extreme heat tape (The tape is a heating wire inside of a shielding, which is powered by 110VAC). The heat is applied to the outside of the pipe, like the coil in a HERMS.The pipe with the heat tape is the enclosed in insulation.

here is his parts list from McMaster-Carr --

1 1 each 4550T141 Extreme-Temperature Heat Tape 13 Watts/Square Inch, 8 ft Length, 624 Watts, 120 V today $69.07 each 69.07
2 2 each 4464K51 Type 304 Stainless STL Threaded Pipe Fitting 1/2" Pipe Size, Tee, 150 PSI today $7.18 each 14.36
3 1 each 4813K124 Standard-Wall Type 304/304L SS Threaded Pipe 1/2" Pipe, 0.84" OD, 18" L, 13/16" Thread Length today $18.65 each 18.65
4 2 each 4464K234 Type 304 Stainless STL Threaded Pipe Fitting 1/2" Pipe Size, Square Head Plug, 150 PSI today $3.21 each 6.42
5 1 roll 9379K92 Ultra-High Temp Foil-Faced Insulation Strip 1/2" Thick, 2" X 12' today $11.39 roll 11.39

Merchandise total
$119.89 Of one section. I used two for a total of 1200 watts..

When I finally get around to fabricating a bottom drain keg for my mash tun, I think this is the way i will go rather than an internal element.

I have been looking at that method as well, and if anyone else is interested, here are a few options to look at for reasonable prices:

http://www.omega.com/ppt/pptsc.asp?ref=STH_SST_SWH&Nav=heam02

Model STH102-080 gives you 1256W with a 1" x 8" tape at 240V for only $88 which should be enough to maintain temps at the very least if not give you a moderate ramp to mashout when wrapped around a copper or stainless HEX and covered with some kind of high heat resistant insulation. There are other flexible heaters on that site as well, could be an interesting new way to maintain mash temps if properly done, however, I have no idea how these elements respond to rapid switching...

 

[shushikiary]

Screwing around with my brew troller I've messed with PWM duty cycles up to 10hz just fine.

The issue becomes the SSR. The element is just a resistor and can switch just fine up to high frequency and still work. The SSR however when you tell it to shut off it doesnt shut off until the zero crossing of the 60hz signal coming out of the wall, so you can only ever get down to 1/120 of a second accuracy for your duty cycle control.

Thus if you're running much under 1hz and using 0 - 100% you will have no change in output power between say 1-5 % and then have a single half wave power change once you cross the proper timing, so your control resolution is reduced due to the SSR once you get much below 1hz PWM period.

 

[Brewer Gerard]

gerry... PID and PWM are not one in the same. Some PIDs support a PWM mode in addition to the normal PID mode, so you can indeed just wire up the PID to the SSR if it supports that kind of PWM behavior.

I built a stand-alone PWM to drive the SSR. A couple capacitors and diodes, a small 555 timer chip, and a potentiometer.

Cool! Do you have a PID working with this setup to hit a setpoint and hold that temp?

 

[Walker]

Cool! Do you have a PID working with this setup to hit a setpoint and hold that temp?

PWM is good for controlling power but cannot maintain a temp automatically. I use the PWM to control my boil kettle trength and have a separate PID for hitting and maitaining temps.