Please help identify temperature sensor and diagnosis/repair

Options
cckriss
cckriss Posts: 43
in Domestic Hot Water

I have a Viessmann Vitocell EVIA 160 indirect water heater.

After taking a quick 7 minute shower and then doing the dishes, the water was not as hot as it usually is. I also did not hear my boiler fire up as I was washing the dishes like I normally hear.


I have pin pointed the POSSIBLE issue to the temperature sensor. I removed the temperature sensor from the TS Well to see what I’m working with. It’s a black cable with a metal cylinder on the tip.

I blew on the metal tip to get it to cool down and then the boiler turned on and the valve opened. I put the metal tip back into the TS Well and the boiler shut off after a few seconds.

So I believe the temp sensor may just be out of spec or something. Is there a chart for me to measure resistance / temperature? I’d also like to have the part number so I can order the correct replacement.

I also confirmed the boiler was working by turning on my hydronic slantfin baseboard heat.

Here are some pictures. I forgot to take a picture of the metal tip.


Thank you

IMG_3958.jpeg IMG_3957.jpeg IMG_3960.png

Comments

  • Alan (California Radiant) Forbes
    Alan (California Radiant) Forbes Posts: 4,875

    Seems that the sensor has lost its calibration, like you said. You may only need a new sensor (20K?), but here is the whole kit. Doesn't get good reviews.

    What make boiler do you have?

    8.33 lbs./gal. x 60 min./hr. x 20°ΔT = 10,000 BTU's/hour

    Two btu per sq ft for degree difference for a slab
  • hot_rod
    hot_rod Posts: 28,569

    if you don’t have the original manual, find it online

    It will have the resistance chart. Do you have an ohm meter?

    Hold the sensor against a cup of ice, then against a cup of boiling water to test both ends if the range

    If the boiler display reads out check temperature there as you warm and cool the sensor. Then you don’t need the ohm meter

    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • cckriss
    cckriss Posts: 43
    edited 3:35AM
    https://forum.heatinghelp.com/discussion/comment/1907676#Comment_1907676

    Boiler is buderus g115. Thanks for the link, maybe I will try a different brand of sensor

  • cckriss
    cckriss Posts: 43
    https://forum.heatinghelp.com/discussion/comment/1907678#Comment_1907678

    i found the manual for my water heater but it does not state the recommended temperature sensor.

    I did not know what model temperature sensor is until the previous poster found it

  • 109A_5
    109A_5 Posts: 4,661

    Hydrolevel's AcuTemp Installation Manual is impressively lame where it concerns the temperature sensor testing or replacement. Often NTC sensors 20 K or 10 K are 20,000 or 10,000 Ohms at 77 degree Fahrenheit or 25 degree C, it could be a digital sensor too.

    Maybe call them.

    image.png
    National - U.S. Gas Boiler 45+ Years Old
    Steam 300 SQ. FT. - EDR 347
    One Pipe System

Categories