HomeRoast Digest

Topic: watlow j-trol temperature controller (11 msgs / 219 lines)
1) From: stereoplegic
picked one of these up on ebay*:http://tinyurl.com/36jrm5*similar to Watlow series 360 temp controller from what i can tell. 
anyone used one of these? i'm thinking of using it for roaster temp 
control w/ a probe in the bean mass, but can't figure out which 
terminals to hook the SSR to (only one shown, as you can see in the 2nd 
pic in the listing). would the one designated as "Solid State Fusac" be 
SSR control + or -? AC or DC? would the other SSR control voltage 
terminal connect to the "N.O. Contact" terminal? i can't find any 
manuals online as this is apparently a much older model than Watlow 
currently offers.

2) From: raymanowen
We had lots of Love, Omega and Watlow controllers at CSMRI, and from 1977 I
was their instrument tech.  The Research Institute always got stuff from
CSM, and there weren't always manuals and schematics [Usually none] with
which to set up the projects.
I could always get manuals by calling the manufacturer or a distributor
On 6/11/07, stereoplegic  wrote:
"When the theme hits the bass, I dance the Jig!" - -Virgil Fox at the Mighty
Wichita (ex- NYC Paramount) WurliTzer- 1976

3) From: raymanowen
Oh, Hell!
It's calibrated for a type J thermocouple. The couple is Iron/ Constantan.
The Iron wire will corrode in a hurry, and the corrosion is Gauronteed to
give an early false junction.
"...similar to Watlow series 360 temp controller from what i can tell." Of
course, there is never any BS from eBay sellers- the caveat is: "...we have
no knowledge..."
I do. If it's a decent controller, you can calibrate the zero and span.
Watlows could. You'd just need a milivolt potentiometer with a good standar=
cell in it, or an ice water bath and a boiling water bath. But that would
only cover half the range of interest unless you built a thermopile with tw=
or more junctions series-connected.
Then you have to read the chart. If you have 5 junctions in series at 212=
you just have 5X the 212F emf, not the 1060F emf. It's non-linear- fo=
the emf/ temperature chart.
Also, the type J thermocouple is near its limit at the 1000F range- mayb=
due to the nonlinearity of the Iron wire. A bare J thermocouple won't last
long around 450, but it would be much more rugged in a 1/8in stainless
steel or Inconel sheath with a grounded junction.
Whatever you do, don't kid yourself- you can put the probe anywhere you
want. Even "a probe in the bean mass" is going to tell you the temperature
of the measuring junction- nothing more.
Any probe well anchored in the bean mass will just give you false readings.
If the probe moves at all, you will get variable false readings, statements
to the contrary by junior Science Fiction writers notwithstanding.
The controller is only a part of the temperature control system. A type J
thermocouple is almost the worst case sensor.
Cheers -RayO, aka Opa!
Got Grinder?

4) From: stereoplegic
the type J thermocouple i'll be using has a stainless steel sheath. i 
would have gone for a type T model i saw listed around the same time, 
but sheathed T thermocouples seem to be much harder to find. the "series 
360" reference was my own, not the seller's. "Watlow j-trol" and "Watlow 
32-06-11 (the model #)" turned up nada on google. their website only 
seems to have manuals, etc. for current models.
raymanowen wrote:

5) From: Jeffrey Pawlan
I love your phrase:  the junior Science Fiction writers on this list
Type J thermocouples corrode in water so don't use them to measure your brew
temps.  But by all means, they are suitable and accurate for measuring bean
temps. That is what I use for the bean temps in my CCR. See
I have inspected my probes many many times and I assure you that the high
temperatures and the oil deposits are more than adequate to protect the open
junction. I have precision calibration equipment and I can confirm repeatable
accuracy of 0.3 deg F of my bean temperature measurements. Some of my probes
have had nearly 1000 roasts without any degredation.
I again stress (very important) that I use double kapton covered thermocouple
wire. This does not shed, melt, outgas, or produce any toxic materials in food
at up to 500 deg F continuously.
Jeffrey Pawlan

6) From: raymanowen
Try Tech Support
Talk to an engineer at 800-884-4967.
(M-F 8:30-5:30 ET)
The link was on the Watlow site.
Cheers -RayO, aka Opa!
On 6/12/07, stereoplegic  wrote:
"When the theme hits the bass, I dance the Jig!" - -Virgil Fox at the Might=
Wichita (ex- NYC Paramount) WurliTzer- 1976

7) From: raymanowen
I found this: *360A-3603-3000* Watlow Series 360 Temperature Controller -
1/4 DIN, On/Off control, Type K input 0 to 2500F, integral setpot dial
control, 10 amp relay output, 120/240VAC line voltage. One new unit
available. $300.00 *$99.00*at: 
On 6/12/07, raymanowen  wrote:
"When the theme hits the bass, I dance the Jig!" - -Virgil Fox at the Might=
Wichita (ex- NYC Paramount) WurliTzer- 1976

8) From: stereoplegic
thanks RayO!
raymanowen wrote:

9) From: stereoplegic
yeah, i saw that, that's one of the sites that made me think it's 
similar to the Series 360. thanks again for all your help researching this.
raymanowen wrote:

10) From: raymanowen
Bottom line:
"Some of my probes have had nearly 1000 roasts without any degredation."
I would never argue with success- If it ain't Busted, Don't Touch! ! !  But=
I ask, would you know that the performance of the junction had degraded, an=
would you be satisfied with a sensor that was only reliable for several
hundred or a few thousand cycles?
Most common temperature sensors are more reliable than a few thousand
cycles- like the thermostat for your furnace, automobile engine, etc.
As for burning up thermocouple junctions, I'm sensitive to that because we
often operated 14ga type K junctions in alumina wells above 2000F.  Or a
3000F glass furnace with Platinum- Rhodium thermocouples in tungsten coa=
alumina wells.
Some people think the sheathed thermocouples are rare- Not so. Anything is
available for a price. For coffee roasting, oxidation and reduction are
possible, maybe not so rapid at the temperatures involved.
What would stop the use of a s/s sheathed type K grounded junction?
Cheers -RayO, aka Opa!
"I'm not a failure. I've just found 10,000 ways that won't work-" - -Thomas
A. Edison

11) From: stereoplegic
finally got my type J thermocouple (w/ stainless probe sheath) 
yesterday. after wiring the power and thermocouple, tried adjusting the 
knob to above room temp. the red LED in the middle of the knob lit up, 
so i tried the "SSR" and "N.O. contact" terminals w/ my multimeter w/ 
the knob at 200F. no voltage shown, despite the lit LED. so i tried the 
"ISO-drive +" and "ISO-drive -" terminals, and again moved the knob up 
to 200F. 15.4V. Voila. turned the knob below room temp, 0V. turned it 
back up, 15.4V. hooked up the SSR (3-32VDC control) to the "ISO-Drive" 
terminals, and turned the knob back above room temp. both the J-trol's 
and the SSR's LEDs lit up. turned below room temp, both went out. above, 
both lit up again. long story short, it works, just not on the terminals 
i thought it would use. now, lets see if i can get the rest of my rig 
hooked up in time for the homeroasters.org contest.
stereoplegic wrote:

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