Virginia Upstairs WF Series 7 seems to spend a lot of time in stage 2 (full-load) cooling

Discussion in 'Maintenance and Troubleshooting' started by rsinglet, Jun 18, 2018.

  1. rsinglet

    rsinglet New Member

    Hi all,

    I have a new construction 5000-ish sqft house in central VA with 2x Waterfurnace Series 7s (separate 4ton upstairs and downstairs units). I have noticed on the energy reports that the upstairs unit does not seem to spend much time in stage 1, or lower stage, cooling. It seems to jump up to mode "C-9" for a short period of time and then turn off when done. I rarely notice it ever in cooling modes less than 9 (my understanding is that modes 1-6 are reported as stage 1 or part-load and modes 7-12 are stage 2 or full-load). It doesn't seem to start at a low compressor speed and ramp up - it just starts on the high side. The fan speed however can be lower while this is happening. The downstairs unit seems to almost exclusively run in the lower stage (C-1 or C-2) and seems to be on for longer periods of time (seems to be working perfectly).

    I spoke with my dealer an he switched the temperature differential settings that trigger the different stages from 0.5 degrees to 1 degree to try and force the 2nd floor unit to spend more time in the lower stage (I may not have the termininology correct here) but this doesn't seem to have made a big difference.

    My understanding is that with the Series 7 the advantage is that it modulates over a range of compressor and fan speeds and should spend most of its time on and in the lower compressor/fan stages to allow for better energy efficiency, dehumidification, and comfort. It should increase to the higher power modes less frequently and in more extreme outdoor temperatures. We have a separate whole house dehumidifier so relative humidity has not been an issue.

    Basically, I am worried that the upstairs unit seems to be short cycling rather than working as intended. Does this seem to be the case and, if so, is this ok? Can this be an issue with the settings or an equipment problem? I have attached two of the recent week-long readouts from the Aurora weblink, one for the downstairs unit showing that it almost always runs in stage 1 (part load), and another for the upstairs showing it spends much less time in stage 1 and more in stage 2 (full load). The temperatures here haven't been too hot lately so the overall energy usage is low (which should make it easier to run at the lower stage?).

    Happy provide more info if needed.

    Any help would be much appreciated,

    First floor energy and part/full load usage

    1st floor unit.JPG

    Second floor energy and part/full load usage

    2nd floor unit.JPG

    Attached Files:

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