I have an IR2 gathering dust since I got my HT-B. Now, I thought maybe if I can somehow mod it so I can manually control fan speed and heating element power, my IR2 could become a useful mini-air-roaster.

I have no electrical/electronics background. I also don't recall seeing such a mod discussed online. That said, I'd appreciate any help to start tinkering

IIRC, the IR2 had 3 fan speeds (plus one more for cooling?). Is there a way to connect a dimmer of some kind to the fan and bypass the IR2 electronics all together? On the heating element, I have no clue if the IR2 does it in steps or just ON/OFF. Bypass to a dimmer possible here too?

Sorry guys, I'm just thinking loud here. Is a very simple mod possible? A couple dimmers, a few wires and we have a completely manual IR2?

Someone over at the Green Coffee Buyers Club has added a PID to his IR2. You might want to check in over there and see if you can get more details, as I only know it was done and not exactly how.

http://www.greencoffeebuyingclub.com

Susan

The big failing of the iRoar is insufficient bean agitation.

Suggest you run the fan at full speed and adjust the heat input. That's how I modded my Fresh Roast for sample roasting and it works a champ.

This could be accomplished quiet easily by wiring the fan directly to the mains [ assuming the fan motor is mains voltage ] and connecting the heating element to a variac.

[EDIT ] The Fresh Roast uses a 12vdc motor driven by a diode bridge dropped across a tap on the heating element. I connect the motor to a 13.2vdc regulated supply for constant air flow rate.

Thanks for the tip, Susan. I searched and searched there but didn't find much details. I understood that a member there (Cpl593h?) has PIDed his IR2, that all.

I haven't opened up my IR2 yet as I wasn't able to locate instructions/pics on modding it in ways similar to what I wanted to do. Anyone knows of such info?

Oops, sorry, I didn't mean to suggest that the hows and wherefores were there. I did think you could post and ask for more information. I would be curious myself, but I'm nowhere near equipped at this point to follow up and actually "DO" anything, so.....I thought I'd send you into the fray and ride along on your coattails....

Susan

Not at all, your reply was clear, thanks again, it was the reason I registered on yet one more coffee-related forum . Posting there? hmmm, it took me a year or two to start posting on HB....so 2011 will probably be the year I start doing so on GCBC .

Back to IR2, I dunno, maybe I'll end opening her up to see what's inside

Wasn't kidding when I said it was gathering dust

I opened her up and it doesn't look simple (to my no electrical/electronics background eyes, hopefully not to yours ). So, I took 3 initial photos till I learn my way around.


1st: the base opened like an egg. The bottom part has what looks like the controls and the upper part should have the heating element and the fan.



2nd: the bottom in focus, what's (A)?



3rd: the meat. There's a thermostat, what looks like a motor (B), for the fan?





Any ideas on what to open up next or modify or test?

I further butchered my IR2, and getting closer to figuring it out but have some questions.

1st is the fan:



It looks like I could simply connect the two wires in the photo to a dimmer and I'm done with fan control. Any thoughts, confirmations?





Next is the heating element (or is it elements????):







-(2) & (3), the fiber string(?) is connected to nothing. The spring is connected to wires (which are then connected to the control board) on the backside. Is this one complete heating element? How should I connect it directly to electricity (well, a dimmer really)?

-(4) & (5), is this another, smaller, heating element? The spring and fiber string(?) of this one are connected together as you can see. Should I connect this one like I would do with (2) & (3)?

-What's (1)?

-What's the thing on the 1st photo(with "???")?

We're almost there, guys . Would really, really, appreciate your insight.

On photo "3rd, the meat", the "Thermostat" looks to be in the position where the roasting pot interlock switch should be. I'm guessing on the other side of the plastic casting, there is a little triangular arm/button with a notch out of it - pushing that should actuate the switch.

The red circle with ??? looks to be a thermal switch - it should open (or close) when a certain temperature is reached. It's likely there as a safety - if the thing hits some magical temperature (let's say 600F), shut down the power, because it's about to catch fire.

The fiber strings look to be there to hold the heating element coils in place, so that they don't wander away and touch something they shouldn't. I see the same construction on air poppers. They are not electrical components, they are mechanical components.

Component identification:
(1) Looks to be either a thermal fuse, thermocouple, or other temperature sensor. I'm guessing that the reason the thermocouple readings are so inaccurate in these things is because of the riveted connections - thermocouples really need to have wires which go all the way back to the measuring circuit. (Every dissimilar metal junction counts as another thermocouple, so you've got a whole bunch of uncalibrated thermocouples working together to throw each other off, plus one real thermocouple that's trying hard to give accurate results.) I'm guessing the leads from here go back to the control board.

(2) to (3) Has the look of the main heating element. Using an ohmmeter (or ohm setting on a multimeter/VOM), I'm going to guess this reads around 15 ohms from point 2 to point 3. If that's the case, hooking it up to line AC should give you about an 8 amp draw, or a 960 watt (input) heater. If it's lower ohms, it should be more amps and more watts.

(4) to (5) look like a secondary heater, possibly used to drop the motor speed in the original design. If it's similar to popcorn machines, that's likely to be 60-70 ohms, which would mean about a 2 amp draw, and about 240 watt heater if hooked directly to line AC.

Hooking the two fan motor wires to a dimmer is probably a bad idea - a fan motor speed control would be better, so you don't burn out your motor, and can get full speed out of it. Poking around and looking at Johnson spec sheets, looks like a 1 amp 120V motor, but under harsh loads that might go up to 1.5 amp. A 200 watt or 2 amp (or greater) fan controller should handle it.

You previously asked about what the thing was on the aluminum heatsink. ("Whats (A)?") Looks to be a voltage regulator, but possibly is a triac. Looks like the control component modules are an AC control board (at 9 o'clock), a low voltage control board (with the LCD panel/buttons, 12 o'clock), and a regulator (6 o'clock).


Happy hacking.

Oh William, thank you, thank you, thank you . . . . that was thorough, clear and extremely helpful.

Espin wrote:(2) to (3) Has the look of the main heating element. Using an ohmmeter (or ohm setting on a multimeter/VOM), I'm going to guess this reads around 15 ohms from point 2 to point 3. If that's the case, hooking it up to line AC should give you about an 8 amp draw, or a 960 watt (input) heater. If it's lower ohms, it should be more amps and more watts.

Yup, 16ohms. So, connecting a wire to each point from a dimmer would work, right?

Espin wrote:(4) to (5) look like a secondary heater, possibly used to drop the motor speed in the original design. If it's similar to popcorn machines, that's likely to be 60-70 ohms, which would mean about a 2 amp draw, and about 240 watt heater if hooked directly to line AC.

This one reads 29ohms, so, something like 4amps/450watts? Dimmer+wires would work here too?

Espin wrote:Hooking the two fan motor wires to a dimmer is probably a bad idea - a fan motor speed control would be better, so you don't burn out your motor, and can get full speed out of it. Poking around and looking at Johnson spec sheets, looks like a 1 amp 120V motor, but under harsh loads that might go up to 1.5 amp. A 200 watt or 2 amp (or greater) fan controller should handle it.

I'll google the difference between the two; but I can just hook them directly to AC for full power, right?

Espin wrote:On photo "3rd, the meat", the "Thermostat" looks to be in the position where the roasting pot interlock switch should be. I'm guessing on the other side of the plastic casting, there is a little triangular arm/button with a notch out of it - pushing that should actuate the switch.

Makes sense as the thing won't run till the pot is locked.

Espin wrote:The red circle with ??? looks to be a thermal switch - it should open (or close) when a certain temperature is reached. It's likely there as a safety - if the thing hits some magical temperature (let's say 600F), shut down the power, because it's about to catch fire.

So the smart thing to do is to try not to bypass it; just in case.

Espin wrote:The fiber strings look to be there to hold the heating element coils in place, so that they don't wander away and touch something they shouldn't. I see the same construction on air poppers. They are not electrical components, they are mechanical components.

only if you knew what I thought of these at first

Espin wrote:(1) Looks to be either a thermal fuse, thermocouple, or other temperature sensor. I'm guessing that the reason the thermocouple readings are so inaccurate in these things is because of the riveted connections - thermocouples really need to have wires which go all the way back to the measuring circuit. (Every dissimilar metal junction counts as another thermocouple, so you've got a whole bunch of uncalibrated thermocouples working together to throw each other off, plus one real thermocouple that's trying hard to give accurate results.) I'm guessing the leads from here go back to the control board.

Leads go to the LCD...probably nothing to do with my mod except maybe to hang a MET TC onto

Man, thanks again, you've made my day!

I bought:
A 250W fan speed control, for the fan.
A 1000W dimmer, for the smaller heating element.
A 2000W dimmer, for the larger heating element.
several wires, connectors, etc.

I'm gonna connect this stuff up asap; if no more cautions/advice is given here.

All sounds good. Those are big honking dimmers, but yes, an incandescent filament and a heating element are extremely similar, electrically.


Remember that you have a neutral wire; this is common between the fan motor and the heating elements.
You also have a hot (power) line, this is common between all the dimmers and speed controls.

If that doesn't make sense, draw it all out first.

I'd suggest adding a switch on the upstream side of all the dimmers, so you can set a position for all your controls and still conveniently turn everything off.

Given the way that I normally end up doing things, I'd probably also add a 3 way (SPDT) switch for the fan control, so I could switch between full speed and a preset low speed without twizzling the knob.

Not the best schematic I've ever drawn, but it should give you a rough idea. The normal switch would be main power - flip this switch, everything goes cold. The 3 way switch should flip between full speed fan and variable speed fan - potentially useful for going into a "cooldown" mode. Use the correct speed control/dimmer for the correct load, and it should all be OK.



Your math is close - on 29 ohms @ 120v, I get 4.1amps, just under 500 watts.

i=e/r (amps=volts/ohms), watts = volts * amps.
(I'm overlooking power factor, because these heating elements can be considered a purely resistive load.)

I AM NOT AN ENGINEER. YOU ARE DOING THIS AT YOUR OWN RISK. I accept no liability for any incidents resulting from the use of any of this purely speculative information provided for entertainment purposes only.

Great, William, thanks for the schematic and everything else!

Is accidentally switching neutral & hot a Bad Thing in this setup?

Probably need to check how that thermal switch operates if you're going to use it. If it's an open on rise, it should read about 0 ohms when cold. Ideally, you can point a heat gun at it while measuring the resistance (clip leads are your friends here) - hear a little "tink" noise, and see the resistance shoot up to open circuit. If you have a thermocouple handy, you can figure out what temperature it's going to do that at.

If that's the case, wiring it into the circuit with the heaters should be OK. Don't wire it into the circuit with the fan - if it over heats, letting the fan continue to run so that the heat goes away is probably a good idea.

I just did a little math on your dimmers - if you haven't opened the 2000W dimmer yet, you might want to exchange it for a 1000W if there is an appreciable cost savings. 16ohms@120V=900W - well within the 1000W dimmer capacity. The 2000W will certainly work, and the heatsink on it should stay cooler than a 1000W dimmer.

coffee.me wrote:Is accidentally switching neutral & hot a Bad Thing in this setup?

Yes and no.

Electrically, it shouldn't matter. Safety says you switch the hot leads.

Always unplug it before moving wires around.

Never work on energized equipment - you're a self proclaimed non-electrical type.

coffee.me wrote:I have no electrical/electronics background.

Go slowly, plan your work, work your plan. Don't get excited; don't rush. Mistakes happen when you try to skip steps or go too fast.
The most important piece of safety equipment is a few inches behind the eyes, just between the ears. Use it.

Thanks for answering the polarity question and for the tips.

Espin wrote:If it's an open on rise, it should read about 0 ohms when cold.

I think it does. When cold, it reads 0.5ohm, but that's also what it says when I make the MM leads touch. I checked where it connects to, and it appears it's online for one of the leads of the larger heating element. So probably no probs leaving it as is.

My IR2 is now fully upgraded to stick shift . . . I think I can get to C2 in 3mins .

As a curiosity, does it seem to work OK with both heaters on full and the fan on full?

What's your intake/exhaust temperatures on full speed fan with heater a, heater b, and both once a stable condition has been reached?

It's an intriguing project.

Yup, all seems OK. I ended up wiring the two heaters together and controlling them thru the 2000W dimmer; it was alot easier to do this way because of how the IR2 heaters were originally wired.

I did a few browns last night and the thing is hot. I got some Brazil (75g) batches to FC(+) in 7mins and one Sumatra to a rolling C2 in 7mins. I didn't log temps, but I recall seeing 600F on the MET TC. I suspect MET can get to 700F in 1 or 2min if required. Do you want me to verify?

Just wondering how hot it can get at full fan speed, and what your ambient is to get up to that temperature.