RoyJ wrote:

Yeah, but Karl's son is one of those TIG welder guys that practices on
beer cans. For what he wants to do, welding his own seems like the best
choice.

Certainly an option. Save a few $ in TC connectors.


I didn't find the TC wire in McMaster, used the Omega site since it had
a good writeup.

McMaster page 541, bottom.


I've always used 'K' wire, you mentioned 'J'. Why/Comments?

No particular reason, just first in the list of supported TC types for
the controller.







Pete C. wrote:
RoyJ wrote:
Just make a probe with standard K type thermocouple wire, do a tiny weld
at the end. It's only the temp of the junction that counts.
http://www.omega.com/ppt/pptsc.asp?r...IRE&Nav=temh06
Looks like they have a 100' min but that would be enough for multiple
probes.

Yea, you can roll your own, and McMaster has TC wire as well. I expect
the OP just want's to get the job done, and not practice TIG welding his
own thermocouples however.

Pete C.


Pete C. wrote:
Karl Townsend wrote:
Each of the evaporators in the apple cooler has a thermostat like item C on
page 603 of http://www.mcmaster.com/ They are mounted on the 13' ceiling in
the dark area behind the evaporator. I have to climb to the top of a 10 foot
step ladder to adjust them and they need several adjustments per season. My
old tired eyes almost can't see the dial anymore, trying to look through
bifocals to the ceiling while holding a flashlight and leaning over a stack
of apple boxes just ain't fun.

So, I'm looking for a better thermostat. First I looked at an electronic
thermostat - item E on the same Mcmaster page 603. I could move it about
four foot down the wall as it has a longer bulb length. That would put it
9-10' high on the wall. easier to see but still need a ladder.

Then I noticed item 331K21 on page 544. If I could lengthen the cables from
3' to 30', the control unit could be placed near the cooler walk door at eye
level - no more ladder. It says the sensor is a thermistor probe with a 3.5'
cable. So, can a thermistor probe cable be lengthened?

Or, any other good suggestions? I'd really like to adjust cooler set point
without a ladder and at the front of the room if at all possible. The back
evaporator often gets stacked in. FWIW, any thermostat just energizes a 220
VAC solenoid to let the refrigerant flow.

Karl
Thermistor temp probes can definitely be lengthened within reason and
just need a little recalibration perhaps.

If you want to do things the correct industrial way, you use a real
industrial temperature controller like 38615K13 on page 544 with a
thermocouple type sensor (pick a type J on page 538) you can readily
locate anywhere (type J extension on page 542)