telling the values of a thermistor

[jimcorrigans]

Hi Folks
After my last posting was so successfull answered I thought I would ask this one and cross my fingers. Here goes;

I am trying to find the difference between different central heating boiler thermistors. I have one that has 23-02 and 1000733M printed on it. Has anyone any idea what this stands for?
Regards
Jim

 

[chemelec]

Probably just the Manufacturers Part and batch Numbers.
I really doubt they tell any of the actual characteristics of the device.

Hi Folks
After my last posting was so successfull answered I thought I would ask this one and cross my fingers. Here goes;

I am trying to find the difference between different central heating boiler thermistors. I have one that has 23-02 and 1000733M printed on it. Has anyone any idea what this stands for?
Regards
Jim

 

[Pommie]

Hi Folks
After my last posting was so successfull answered
Jim

Did you re register as you appear to have only 1 post!!

Mike.

 

[jimcorrigans]

Thanks for your help, is there a way of finding out the values of a thermistor?
Regards
Jim

 

[jimcorrigans]

Hi Mike,
I am a bit confused because I thought it was this site that I had used in the past, my computer crashed and I lost everything so prehaps I have made a mistake. Sorry if I have confused anyone.
Regards
Jim

 

[KMoffett]

Jim,

You posted on:

**broken link removed**

I recall talking to you.

Ken

 

[chemelec]

Thanks for your help, is there a way of finding out the values of a thermistor?
Regards
Jim

You just Measure the Resistance with an Ohm-Meter and at a temperature of 20 Degree Celsus. (About 70 Defrees F)

A "PTC" Type thermistor Increases in resistance as the Temperature Rises.

A "NTC" Type thermistor Decreases in resistance as the Temperature Rises.

Gary

 

[hysteresis]

Jim,

Have you looked in the boiler's installation instructions? They quite often include graphs (Temperature vs Resistance) for the thermistors used, to assist in fault diagnosis.

John

 

[chemelec]

Jim,

Have you looked in the boiler's installation instructions? They quite often include graphs (Temperature vs Resistance) for the thermistors used, to assist in fault diagnosis.

John

There are Thousands of Different thermisters, all with different Grap Plots, Wattage and Other Ratings.

And they are used in MANY Electronic applications, Only a small percentage in Boilers.

The Nominal Resistance Rating is at 20 Degrees Celsus, but All Manufacturers also show there resistance variation verses temperature.

 

[hysteresis]

Hi Gary,

Sorry, but I fail to see your point. Jim indicated in his opening post that he wanted to compare central heating boiler thermistors. So, what is the relevance of

There are Thousands of Different thermisters, all with different Grap Plots, Wattage and Other Ratings.

And they are used in MANY Electronic applications, Only a small percentage in Boilers...

Central heating boiler thermistors are used as water temperature sensors. Any significant self-heating of the thermistor would introduce a temperature measurement error. Hence, the thermistor Wattage rating is irrelevant.

The only important electrical parameter is the thermistor's characteristic curve. This is quite often provided, in graphical or tabular form, in the boiler manufacturer's installation/servicing instructions. For example, the thermistor used in a number of boiler's made by Chaffoteaux & Maury is characterised in their "Calydra green" Maintenance and Service Guide as follows:

REGULATION

Temperature regulation for both C.H., TSS® and D.H.W. circuits are controlled by 3 thermistors. The C.H. knob allows the adjustment of the temperature between 35 and 85°C. The D.H.W. temperature is limited to 60°C. TSS®, D.H.W. and C.H. thermistors are identical and interchangeable.

Resistance value are
-5000 ohms at 25°C
-2631 ohms at 40°C
-620 ohms at 80°C
-255 ohms at 110°C

Regards,

John

 

[chemelec]

Sorry, I forgot about his Origional post.
I was just commenting on Thermistors in general.

SEASONS GREETINGS......Gary