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  1. #1
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    Measurequick head pressure targets not working correctly

    Measurequick keeps setting my target head pressure wrong. If I set it to 10 seer equipment (25° over ambient) and outdoor is 70 manualy enterered or using probe it keeps setting target head pressure saturation at 105°. Also when I set to 13 seer (20° over ambient) it sets target saturation at 100°. It keeps setting target 10° higher than its supposed to. It's not doing it everytime but alot of the times.
    Anyone else seeing this. App is up to date.

  2. #2
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    I just did a bunch of testing and everything is working fine. I used 70 degrees and 85 degrees. That said, we are doing some target adjustments for high WB on the evaporator that will drive the DTD target pressures but not the design DTD. So if you do the math, the calculated DTD would be higher but only for the current load conditions. As the conditions return to normal so with the design DTD.


    Jim
    JLB,

  3. #3
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    Quote Originally Posted by kra2y View Post
    Measurequick keeps setting my target head pressure wrong. If I set it to 10 seer equipment (25° over ambient) and outdoor is 70 manualy enterered or using probe it keeps setting target head pressure saturation at 105°. Also when I set to 13 seer (20° over ambient) it sets target saturation at 100°. It keeps setting target 10° higher than its supposed to. It's not doing it everytime but alot of the times.
    Anyone else seeing this. App is up to date.
    I believe i noticed but ignored this yesterday on an old basic 10 seer ac i was doing a report on, it never put the HP target triangle in place even though i hooked up everything normally and said some parameters missing to get proper targets or some such.. it was odd

    I was using an up to date Ipad and the 17SEER+ 410 unit next to it it was fine..

  4. #4
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    Quote Originally Posted by jim bergmann View Post
    I just did a bunch of testing and everything is working fine. I used 70 degrees and 85 degrees. That said, we are doing some target adjustments for high WB on the evaporator that will drive the DTD target pressures but not the design DTD. So if you do the math, the calculated DTD would be higher but only for the current load conditions. As the conditions return to normal so with the design DTD.


    Jim
    what creates that target arrow over the pressure gauge? what hardware and calculations is it using to determine how it gets this target? even though i havent been using a discharge probe of late it typically gives me these targets, yesterday on the 10seer r22 system it was not..


    Name:  BarbSch r22 10.jpg
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    Name:  barb sch 410 17plus.jpg
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  5. #5
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    The Return air target is set by RADB, and the head pressure by ODA temp.
    JLB,

  6. #6
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    OK. I figured it out when it happens. I am using iconnect and pressure imanifold probes and imanifold temp probes. Head pressure target is correct only if return temp probe is not synced. As soon as return temp syncs the target head pressure goes up 10° no matter the seer selection. Turn off return temp probe and then the target will go back to correct. Turn on return probe again and target goes up 10 again. Turn off return probe again and target goes back to correct. Up to date app and update in the app.

  7. #7
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    Quote Originally Posted by kra2y View Post
    OK. I figured it out when it happens. I am using iconnect and pressure imanifold probes and imanifold temp probes. Head pressure target is correct only if return temp probe is not synced. As soon as return temp syncs the target head pressure goes up 10° no matter the seer selection. Turn off return temp probe and then the target will go back to correct. Turn on return probe again and target goes up 10 again. Turn off return probe again and target goes back to correct. Up to date app and update in the app.
    I am testing it right now and cannot duplicate what you are seeing. On your pressure probes, do you have the ODA sensor plugged into the T2, and the SLT to T1, nothing plugged into the RH probes? What is your RH on the probe? Is it exactly 10 to the 10th?
    JLB,

  8. #8
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    Again, what I think you are seeing is the high latent load correction. You can overload the coil with latent capacity and drive the suction and head up accordingly. If the RH and DP are really high, the correction is applied when the probe is turned on. If you benchmark, and look at the “custom DTD you will see that the true DTD is not affected. It is only the calculation of the pressure target and that is due to the high latent load and how far the evaporator coil is below the dew point temperature.
    JLB,

  9. #9
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    Thread Starter
    So the return temps are changing the head pressure targets? I thought only outdoor temp affects head pressure target?
    I un installed the app and reinstalled a few times and it quit doing that now. I was testing in my van under same conditions the whole time when it was acting wierd and after re installing app.

  10. #10
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    Quote Originally Posted by kra2y View Post
    So the return temps are changing the head pressure targets? I thought only outdoor temp affects head pressure target?
    I un installed the app and reinstalled a few times and it quit doing that now. I was testing in my van under same conditions the whole time when it was acting wierd and after re installing app.
    The return only effects the head pressure when the latent load load is way out of the typical range. Basically the latent load is overloading the coil. Under typical conditions the offset never comes into play.
    JLB,

  11. #11
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    So I have been using the app now for a few weeks and almost every job it is raising the target suction pressure and target head pressure but my actual pressures are consistently where the normal dtd are set if the targets weren't raised from the high humidity in the return. I have yet to see 1 system run at these targets I keep getting from the elevated humidity over 60%. I like to show my customers the screen when everything is on target but more times than not the targets for pressures are raised up from the dtd and it shows my pressures are off. If I get a return with less than 60% humidity then it seems to give me standard dtd targets and my pressures are right on target.

    I have to keep telling the app that I have a much higher seer system than I actually have to get the target head pressure to show its on target. On 13 seer evaporator coils I have to leave it set to not high efficiency evaporator coil. But on 10 seer equipment I can't lower the dtd any lower so it shows target off of actual pressure. I would realy like to have option of custom evaporator dtd for when have very large oversized evaporator coil to get more accurate targets on suction pressure because when have oversized evaporator the suction pressure goes up higher but no way to raise the target suction pressure. Some of the 16 seer systems have coils a few tons over the condenser size

  12. #12
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    I will make a slight adjustment to when the targets are adjusted, I’ll change it from 60 to 65%. Let me know if that works better for you. I was looking for some feedback. Thanks.

  13. #13
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    Thread Starter
    When will you be updating the app?

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