Johnson Control Thermistor/temp sensor

Can anyone recommend a replacement temp sensor for the aA419? Need to get a longer one. Does it have to be specifically for the A419?

Thanks!
David

IIRC, you can use any thermistor sensor that meets the 1,000 ohms @ 25*C specification. The spec is listed in the manual supplied with the controller. Please verify this before ordering a replacement as I could be mistaken. You can download the manual from the Johnson site if you don't already have one. Check out the Dwyer site. They sell the probes for a lot less than Johnson gets.

You could also simply splice more wire onto your existing probe to lengthen it. That's what I would do.

Splicing is a good idea, is there a specification listed in the manual (that I to download) for the cable or is it just for the thermistor?

adurotec said:

Splicing is a good idea, is there a specification listed in the manual (that I to download) for the cable or is it just for the thermistor?

Click to expand...

Yes, IIRC it explains how to extend the leads. What stood out in my memory was that you could run the lead for a very long distance if desired without significantly affecting the accuracy, but you must use the recommended wire gauges.

Here's what I found in the manual:

• A99 temperature sensors are not polarity
sensitive. Wire the leads to (+) SEN and (-) COM
on the sensor terminal block (TB3). See Figure 2.
Keep the leads between the control and sensor as
short as possible/practical in your application. The
additional resistance in long sensor leads creates
error between the actual temperature and the
displayed temperature. Refer to Table 1 when
extending sensor leads.
Table 1: Maximum Recommended Sensor Cable
Lengths and Wire Sizes
Wire
Gauge
Maximum Sensor Cable Length*
feet (meters)
16 AWG 500 (150)
18 AWG 300 (100)
20 AWG 200 (60)
22 AWG 125 (40)
* At the listed maximum cable lengths, there is less
than 1F° (0.6C°) error in the actual temperature vs.
displayed temperature.