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Testo 320 will not read CO2

GroundUp
GroundUp Member Posts: 1,904
Testo 320 was brand new about 6 months ago, I've used it maybe 10-15 times and kept up on drainage and filter changes, everything by the book. Today I fired up a UFT-120 heating a new 5000 sq ft house and 1500 sq ft attached garage and the Testo would not read CO2 (or efficiency). The boiler was converted to LP with a new mixer from HTP and seemed to be burning nicely through the sight glass but neither low or high fire showed any sign of CO2. I was able to dial the PPM down to around 100 but nothing further. Do these have a separate sensor for CO2 or what the heck? I'm admittedly new to the combustion analysis world so please excuse me if this is a stupid question, but I need to get this thing running ASAP and have another one to install tomorrow. Thanks in advance for any information!

Comments

  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 15,511
    as far as I know the control senses 02 with an 02 sensor and then calculates C02.

    I had trouble with mine once it would only partially read some things. I think I found the sensor cable wasn't plgged in all the way.

    Other than that I would suspect a bad 02 sensor but usually the screen tells you that

    others will know more than me I am an old dumbbell bottle guy
    GroundUp
  • kcopp
    kcopp Member Posts: 4,431
    I had a similar issue 2 months after I had mine recalibrated. As Ed suggested make sure everything is plugged in well. Then try turning the unit on and off a few times to get the pump inside to expel any water. Make sure the fliter is a new one. make sure the water in the unit is drained/ dumped out.
    Mine worked fine the next day.
    GroundUp
  • GroundUp
    GroundUp Member Posts: 1,904
    Thanks guys. I did turn it off and on 6 times, replaced the filter twice, disconnected and reconnected the probe twice, tried draining water 2 or 3 times, nothing changed.
  • SuperTech
    SuperTech Member Posts: 2,152
    Open up the unit and make sure the rubber hoses aren't cracked or damaged. I would also make sure sensors are plugged in and connected to the board securely. I had a similar problem but it turned out that the drain plug wasn't completely seated in top of the unit causing the pump to pull in air and messing up the readings. I was getting good temperature readings and it was measuring some CO but my O2/CO2 was way off.
    Testo designed the 320 so the sensors could be field replaceable so it shouldn't be a problem if you open it up and check it out.
    GroundUp
  • Zman
    Zman Member Posts: 7,569
    edited March 2019
    If you are reading O2 and CO but it is not showing the calculated CO2, I suspect there is a setting that has changed. Somewhere in the menu you can change what is displayed.
    I ignore CO2 because it is not an actual measurement and would probably not notice if was missing.

    If you are not reading O2 either, check that the sensor is seated and the pins are straight. I recently changed my O2 sensor and did not get it aligned correctly the first time.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • GroundUp
    GroundUp Member Posts: 1,904
    Zman said:

    If you are reading O2 and CO but it is not showing the calculated CO2, I suspect there is a setting that has changed. Somewhere in the menu you can change what is displayed.
    I ignore CO2 because it is not an actual measurement and would probably not notice if was missing.

    If you are not reading O2 either, check that the sensor is seated and the pins are straight. I recently changed my O2 sensor and did not get it aligned correctly the first time.

    Considering CO and CO2 are the only parameters HTP lists for tuning, I kind of need the CO2 reading. O2 is reading, but at 21%, so I assume there is no CO2 available to read at 21%. Everything is seated and pins are straight. Probe was tightly sealed in the flue. Everything has been done the same as the last 10 times I used it but the readings are stupid

  • SuperTech
    SuperTech Member Posts: 2,152
    edited March 2019
    The percentage of O2 in fresh air is 21%. Your O2 sensor or the board it's plugged into is the problem if the pump is working and the CO sensor is good.
    GroundUp
  • neilc
    neilc Member Posts: 2,700
    any chance you forgot to press the start button?
    known to beat dead horses
    SuperTech