modifying a Thermo Neslab RTE 7 Digital One heater/chiller

[Bubble bobble]

Hello,

I hope someone can help. I'm a scientist, working in a university, building my own experimental setup. I want to modify a Thermo Neslab RTE 7 Digital One heater/chiller (water bath recirculator).

The recirculator measures the temperature in its own water bath, I want to move the temperature probe to another (external) water bath.

After opening up the controller (top) part of the device I'm guessing that the temperature probe is a metal rod, partially encased in black plastic. It has 4 tiny wires running into it: 2 orange wires and 2 blue wires.

First question: Have I correctly identified the probe?

Second question: If so, can you forsee any problems with me removing the probe and extending the length of the wires from its current length of 1 foot to a new length of 6 feet, and placing it in an external water bath.

I'll have to carefully program the controller to handle the new response time, but I hope that will be easy enough to do.

Any advice at all is appreciated.

Damien

[Brian_UK]

Hi Damien and welcome to the forum.

Any clue as to the make of the controller?

Wiki has this info on 4-wire sensors...
http://en.wikipedia.org/wiki/Four-terminal_sensing

or this is better..
http://en.wikipedia.org/wiki/Resistance_thermometer

[NH3LVR]

You can find some information on that chiller here.
http://www.coleparmer.com/Assets/man...3500Series.pdf

Although I do not see your chiller listed this is a good resource.
http://www.chillercity.com/manuals.php

[Bubble bobble]

Thanks for the feedback. I have looked at the manuals for the device, but they did not contain the kind of detail I required. By "controller" I mean the "Digital One" top part of the device (includes heater and a bunch of electronics).

But it's going ok so far: I managed to to remove the RTD probe from the unit without problems. Looks like I simply need to extend the 4 cables cable by ~6 ft by inserting a new joint. I also have a second option of buying a second probe with sufficiently long cables. Chris at chillercity.com was really helpful. I should be OK from here on in.

Damien

[paulg88]

Sounds like you've found your probe(rtd1). I can't see why extending it won't work, but failing that, a second external probe (rtd2)is available for those chillers I think. When circulating to an external bath, remember when sizing the bath to keep within the cooling/heating capacity range of the chiller.
Best of luck,
Paul.