RowJ

I have read the pyro probe measures resistance between two different length wires and their length must not be altered. Correct?

I had the ISSPRO red/white (shorter of the two) wire break off at the ring attacher coming from the probe. Had to shorten the wire about 1 inch to reattach. Will this affect my reading? If so, am I now reading higher or lower than with full length wire?

Readings appear similar to before...but not positive.

Signed: Electrically Challanged.

signature600

The pyro (thermocouple) measures temperature with two diferent metals, not lengths.

The reason the wires shouldn't be cut is that the guage knows the resistance it should be seeing, and shortening the wires will change this! How much it throws it off...don't know!

Help at all, probably not quite what you were looking for?
Chris

pitr

Well, 22 guage wire (it may be larger wire then that so the results would be even smaller then this) has a resistance of 16.14 ohms per 1000 ft, or .001345 ohms per inch. So if this where using 12v at 1amp (i am sure it is WAY less then that) you would see the voltage drop from 12 to 11.998655 by removing 1 inch of 1 wire. I rather doubt the guage can detect that.

-Matt

HOHN

Will it affect the reading? Yes!

Enough to care or notice? NO!

infidel

The pyro gauge is nothing more than milli-voltmeter, the sender is a thermocouple that produces different voltages at different temperatures.

The not cut or add wire idea is a myth. I've installed pyros in pusher motor homes with almost 40' of wire.
First time checked with just 8' of wire on a drive, after adding 32' more wire there was no noticeable difference on the gauge.

RowJ

Thanks! Have wanted to add some wire and re-route the probe wire for over a yr. Now I can!

RJ

RustyJC

HERE is a good explanation of how thermocouples work. The Type K (chromel/alumel) is most commonly used with pyrometers on our trucks.

Rusty

hotdram

RJ,
Just measure the temperature with your finger
That's how I test my power supplies. If a component gets hot enough that I can't put my finger on it and hold it there without removing it immediately, the part is too hot and dissapating too much power (heat). My finger is good up to about 1 Watt

~Rob

RowJ

Great reading Rusty...Thanks.

Name change for Hotdram...
from "Underoo Man" to "One Watt Rob"!

RJ

hotdram

One note on Thermocouple wires, at work we weld the ends together, we do not solder them together. Soldering them together yields a more resistive joint that will affect your reading.

(Looking where to buy K extension leads)
~Rob