WF7 Energy Monitoring Constant Fan Wattage

Discussion in 'General Discussions' started by gsmith22, May 28, 2020.

  1. gsmith22

    gsmith22 Member

    Ran across a weird phenomena. I have two Waterfurnace 7 Series units (3T and 4T). Both have energy monitoring and both have electric backup heat packs installed. I happened to look at the energy usage the other day and the fans in both units show 38W being used at all times that the units are running regardless of actual fan speed; 0W being shown when the units are off. This seemingly implies that the fan CT is doing something.

    When the units were first installed and put into service (Oct 2019), the fan wattage for both units would ramp up and down as fan speed ramped up and down with compressor speed. 38W was probably the fan speed 3 energy use (if I remember correctly). In Dec 2019, electric heat packs were installed in both units (delayed due to electric service and load panel upgrades needed). I can't remember if the fan energy use ramped up and down following that or not. But, I bring it up, because I see from the electric heat pack installation instructions, that the CT for the fan is supposed to be shifted from the fan brown wire (factory installed location) to the purple wire attached to the elec heat pack on 15kW and 20kW elec heat units. My 4T unit has a 15kW heat pack but my 3T unit has a 10kW heat pack. Both units have the fan CT donut on the brown wire from the factory.

    At a minimum, it would seem like the fan CT on the 4T needs to get moved to properly report energy usage. But per the heat pack instructions, that doesn't seem applicable for the 10kW heat pack on the 3T unit. So I'm not sure this is the source of my overall energy use reporting issue. Anyone run into this issue previously or can confirm the installed location of their fan CT for 3T or 4T units with or without heat packs?
     
  2. SShaw

    SShaw Member

    I've posted on here that my WF7 fan usage never drops below about 38W, which can't be right. I've also found that measuring the usage with a power meeter shows consumption as low as 15W. So, the 38W seems like the minimum reported when the CT is active.

    I've looked into the wiring when AUX is installed. The need to move the CTs depends on how the wiring is done. The default configuration, without AUX installed, powers the fan from the same circuit breaker as the compressor.

    In the instructions for the AUX pack, WF recommends changing the wiring so that the fan is powered from the circuit breaker feeding the the first stage of the AUX. This is done so that if your compressor has a fault that trips the breaker, you can still run the fan and the AUX of the breaker feeding the AUX. WF provides a wiring harness with the AUX kit to support the wiring change.

    In my case the installer left the fan wiring at default, in case I chose to disable AUX by shutting off the two breakers in the panel.

    The instructions for moving the CTs are in the AUX installation manual. If you don't have it, I can probably find my copy. I believe the change requires removing the 220 leads feeding the AUX, so you need to be careful.
     
  3. gsmith22

    gsmith22 Member

    i recall you posting about the constant 38W - that was back when mine would move up and down with the fan speed :). But both of my units are now either 0W (fan off) or 38W at any and all fan speeds so seemingly not quite the same issue. I wouldn't care too much if the reported values were slightly off from the true power usage across all speeds, but the fact that it doesn't move up and down indicates something is right and I'm not sure what changed other than the AUX install (about 2 months after the units were fired up).

    I have the instllation instructions for the AUX. Both the 3T and 4T fans are wired so that they are fed through the first stage of AUX. And both have the CT donut on the brown wire (factory position) so I pretty sure the installer just forgot about moving the CT in the 4T unit during the 15kW AUX install. I wonder why they don't recommend moving the CT when you have 10kW or less AUX (as in my 3T unit)? Regardless, both units are operating the same for energy use readout which indicates to me the issue isn't the location of the CT and something else. They have quick disconnects on both the brown and purple wires so swapping the position of the CT is very easy.
     
  4. SShaw

    SShaw Member

    I was thinking the issues could be related in that the fan wattage reporting seems to be either OFF and reporting zero or ON and reporting a minimum of 38W regardless of what the CT is doing. That would explain getting 38W with the CT on the wrong wire.

    The documentation I have describes moving the blower CT for all AUX packages, 5W though 20W, so you may not be looking at the same documentation as me. My document is dated 11/18 and is the paper that came with the AUX kit. I cannot find this online--only an older revision online.

    Look at page 3 section 11D), third bullet: "... the BROWN wire that is routed twice through the current transducer will need to be replaced with the BLUE wire that is connected to the auxiliary heat power block..."

    The procedure is the same on all units, so I can't follow your reasoning on why it's not the CT. Based on the instructions your two units should operate the same, so I would expect the issue is the CT on both units.
     
  5. gsmith22

    gsmith22 Member

    The document I have from the AUX installation is named IG1575EW and is dated 11/18 so I think it is the same as yours - I can't find it online either. My 3T unit has the EAL10B and my 4T unit has the EAL15B so page 3 section 11D is applicable. In re-reading that sentence from the third bullet point in 11D, I now see what you are talking about and I was mis-interpreting it.


    The entire sentence is "On units that have the Aurora Advanced Control option and variable speed ECM blower motor, the BROWN wire that is routed twice through the current transducer will need to be replaced with the BLUE wire that is connected to the auxiliary heat power block or from the breaker on the EAL(H)15B and EAL(H)20B heater kits."

    The way it was written, I assumed that the sentence was applicable to only the 15B and 20B heater kits. I now realize that the "auxiliary heat power block" is present on all of the heater kits 10kW and lower while the 15kW and 20kW heater kits have the breaker panel. I don't understand why they didn't make that clearer with listing the ones with the heater block like they did with the breaker panel. My 10kW has the power block and my 15kW has the breaker panel and after studying them and re-reading your post and these instructions I now realize my error.

    I'm going to try swapping out the brown wire with the blue wire for the CT and see if that solves the issue. Thank you for keeping on me. I'll report back hopefully with success.
     
  6. SShaw

    SShaw Member

    Yeah, that's the same document that I have. I have the EAL15B. Apparently the H mode is for horizontal units and vertical rear discharge units. I guess the key to understanding applicability of the instructions is the heading of section 11D, which enumerates all the applicable heater kits.

    This stuff can be confusing if you are not working with it every day. I was thinking of the CTs for the AUX wattage measurement when I thought you needed to remove the 220V leads.

    Good luck. I hope the simple fix solves your issue.
     
  7. gsmith22

    gsmith22 Member

    moved the fan CTs to the blue wires (from the brown wires) and no change. same 40W shows in Symphony for fan power use regardless of fan speed. 0W when no fan is running. Its frustrating because it definitely showed varrying wattage as the fan ramped up and down previously. Don't know when it changed to this constant state. I find it hard to believe that both units would have simultaneously had CT failures on the fans too so its got to be something common to both units. Do these things download new software from Waterfurnace via AWL? Think it could be an issue on their side and not necessarily a problem with the units?
     
  8. SShaw

    SShaw Member

    Sorry to hear that didn't solve it.

    I've haven't heard of automatic software downloads. The AWL manual says a USB kit is required to update software.

    Does the thermostat report the same fan wattage? Does the virtual AID tool report the same wattage? I can't see how they'd differ, but worth checking.

    If you wanted to debug this yourself, I guess you could check the wiring to confirm whether the fan is powered off the brown or blue wire, check to make sure the blower CT is still wired to the AXB, and check the AID tool "Sensor Kit Setup" blower setting to make sure it's set for ECM and not PSC.
     
  9. gsmith22

    gsmith22 Member

    thermostat and virtual AID tool report same wattage; wiring to the fans looks correct (I walked through the AUX installation steps); AID blower setup is set to ECM so all that checks out. and all of this seemingly worked during the heating season so I wouldn't have a reason to suspect any of that but always good to check.

    Units are now in cooling mode if that wasn't clear. Its not "hot" here but mostly really humid (~80%) so I had turned on cooling earlier yesterday leading to my post about the fan wattage. My prior experience with the fan wattage readout ramping up/down with fan speed was in heating mode. It occurred to me that cooling is setup with -15% fan output in the AID and I started to wonder about whether I was seeing the steady 40W because the fan wasn't really running at say speed 5 but something less than that due to the cooling setup leading to your situation with a lower floor on the fan wattage because the CT isn't sensitive enough below that floor. I'm not sure how this aspect actually functions with the derating of the fan for cooling in the unit setup. Its currently at -15% which is the default (shocking everything was setup to default by installer) but from reading that seems correct - ie you want lower airflow for dehumidifying. But that lead me to the following:

    I was looking through the manual for the color touchscreen thermostats (TPCC32U01) and noticed that I didn't have a "humidity" button on the menu (gotta love the thoughtful commissioning done by the installer!). Read through the installer setup section for the thermostat and added dehumidifying so that I can set active dehumidifying features for cooling. Dehumidifying is currently set to "auto" for both units but after I did that, the units started cycling on/off presumably to lower humidity (its been running 65% humidity inside because this was not setup). During those unit cycles, the fan speed on both units got up to 7 or 8 and all of a sudden it began report fan wattage at like 130W for fan speed 7 and 105W for fan speed 6 (two that I happened to see). This leaves me scratching my head - was the cooling air flow setup (-15%) causing truly low fan speed/wattage even when displaying a relatively high speed? Did me turning on the dehumidfying function than cause the fans to use their "real" speed and thus report a higher wattage? I don't really understand the cooling air flow setup (-15%) and how that actually affects the reported vs actual fan speed. On the dehumidifying aspect - what does "auto" dehumidifying do vs a manual specific set point? I have read the various WF documents but none seem to really elaborate on the dehumidifying aspect when in "auto" - is it a moving set point, specific setpoint, etc.
     
  10. SShaw

    SShaw Member

    Strange that it just started working. Could be a bug in the WF firmware.

    I've been alternating between heating and cooling here the last couple weeks. I started out with the dehumidify feature OFF but now it's ON. No impact to the fan wattage reporting on my system. I've also got the default -15% airflow.

    I believe the -15% lowers the delivered CFM at a given numerical fan speed, rather than lowering the numerical fan speed used, but I'm not certain on that.

    There's no documentation on how dehumidify works, that I've seen. From watching the system, I see that this setting will cause the system to ramp-up the compressor and ramp-down the fan to minimize the LAT, which removes more water. I've seen it as low as 34 deg or so. I've also noticed that the system will overcool a bit. I've also noticed that the system has come on with no calls for cooling, solely to dehumidify, which surprised me a little. It opens all zone dampers when it does that.

    My humidity is set to auto. Seems like the dehumidify features (higher compressor and lower fan) come on above about 50% humidity inside.

    One other thing I found was the thermostat's humidity sensor is way off. Compared to a calibrated humidity sensor, the thermostat reads about 16% high. There's an offset, but it only allows a 10% adjustment.

    Before adjusting the offset, the system would run at C9 way too often because it thought the humidity was too high, so the error has a substantial impact on performance. After adjustment by 10% it seems to work OK, but it's still off. I wonder whether I should try to get the STAT replaced under warranty, since the humidity is still reading about 6% high.

    The AC has only been running 1.8 hrs since midnight, and it's 72 degrees and 45% humidity inside, versus 80 degrees and 81% outside, so the system seems to be able to lower the humidity pretty well.
     
  11. gsmith22

    gsmith22 Member

    Watching the system turn off and on, several patterns have developed. For fan speeds of 5 or less, you get a flat 40W. For fan speeds 6 and above you get higher wattage reported (~90-100W at 6, ~130-150W at 7, ~190-200W at 8, and ~290-300W at 9). So seems to be working right at speed 6 and above but flatlined below.

    In order to lower CFM, you have to lower fan speed. There is no getting around the fan affinity laws. This chart lists cfm for designed fan speeds:
    upload_2020-5-29_12-9-14.png



    Based on fan affinity laws, fan speed and flow (cfm) are directly proportional so in order to lower cfm by 15% you need to lower actual fan speed by 15%. At the lower range of this chart (speeds 1-4), individual cfms have about 30% range in between values where as at the upper range (5 and above), there is more like 20% in between. So my guess is, with the -15% in fan speed for cooling setting in AWL, something like speed 4 in heating may look like speed 3.5 in cooling while speed 8 in heating looks very close to speed 7 in cooling. WF doesn't go to the trouble of adjusting the speed reading - 1 is 1, 2 is 2, etc. but speed 2 may mean different cfm in heating vs cooling.

    Those same fan affinity laws predict that power consumption is proportional to the cubic of fan speed. So what I think may be happening is that the lower range of fan values have power consumption that is already low and reducing it another 15% (during cooling) makes it drastically lower (because of the cubic function) and much lower than the fan CT can measure. So likely have below 40W in speeds 2-4 but just can't be accurately measured by the equipment. Switch to heating and the fan speeds go up bringing the lower speeds of 3-4 into the measurement range of the CT.

    I think I may understand what is occurring but would welcome any insight: Prior to me turning on the dehumidification feature last night, I was only getting cooling to meet temperature set points so the system wouldn't be on long and fan speeds would never get above about 5. In combination with the CT being on the wrong wire, lowering of fan speeds by 15% for cooling, and not getting fan speeds above the lower range, I was only seeing 40W in the energy use. Same was true after I moved the CT to the right wire. But, once I added the humidification option to the thermostats, then I started seeing the higher fan speeds and the changing of the energy use reporting for the fan above 40W. So in summary, I think it is all working correctly but just that there isn't enough granularity on the fan CT in combination with reduced fan speeds/energy use in cooling.

    Separately, I am going to calibrate the temperature and humidity of the thermostats because I feel like I have the same issue as you - system comes on at C9 to lower humidity when it is already below temperature set point and doesn't feel humid. Thermostat says its 60% humidity but I have a feeling that isn't correct. I'm freezing my ass off here!
     
  12. SShaw

    SShaw Member

    Let me know if you are able to calibrate the TSTAT or if it's off by more than 10%, like mine is.

    I'm sure your theory is right. In heating mode, I've observed a lower limit of about 48W in Symphony's reported fan power, resulting in the same reading at low speeds, like you are describing. I've been looking to see if anybody else experiences the same issue. From what you are saying, the answer is yes.

    In the table below are measurements I took of the fan speed with a power meter along with Symphony's reported wattage. These were taken in fan-only mode with the AID tool. Similar to you, I get flat readings at F4 or less from Symphony, but the actual measured fan power is less.

    If cooling mode lowers the CFMs at a given "fan speed," then that should push the flat area up from F4 to F5 or higher.

    In fact, that's exactly how my system behaves. I have a screenshot of Symphony in cooling mode I took a few days ago and I see 46W for the fan at C9/F5.


    upload_2020-5-29_12-58-53.png
     
  13. gsmith22

    gsmith22 Member

    yes the behavior seems the same. I resurrected an old thread yesterday where someone reported a similar issue: https://www.geoexchange.org/forum/threads/wf-symphony-energy-usage-display-wrong.7342/

    i read other threads too where attempting to measure watts being used with a meter results in inaccurate measurements because of phase shifting employed by the unit. here is one example: https://www.geoexchange.org/forum/t...onitoring-not-accurate.6822/page-2#post-59515 So I think that is why your Symphony columns and Meter Z1+Z2 columns don't match up
     
  14. SShaw

    SShaw Member

    Thanks. That thread doesn't really address the issue though, does it. Doc rightly says BS, the fan wattage should vary with speed, but doesn't give data for wattage below Symphony's apparent lower threshold of ~40 watts.

    Regarding the measurement... Symphony necessarily suffers from that inaccuracy because it measures only the amperage. My meter is a true power meter and doesn't have that inaccuracy. It simultaneously measures voltage, amperage, and phase angle, so it's reporting the actual real-time power reading. Symphony doesn't measure voltage. Symphony assumes a constant value, or you can enter a measured calibration value. Symphony must assume a phase shift, so it's only an estimate.

    My meter also has Bluetooth connectivity, so it can measure while closed-up inside a running unit. Taking the door off lowers the static pressure and substantially affects the power used.

    In another thread I posted this chart. This is the measured actual fan power for only Zone1 open and for both Zone1+Zone2 open. The latter uses less power, because the static pressure is less.

    [​IMG]
     
  15. gsmith22

    gsmith22 Member

    out of curiosity, what meter(s) do you have? I have been looking at getting a fluke multimeter as well as a fluke clamp ammeter for a variety of upcoming projects (car stuff, solar stuff, etc.).
     
  16. SShaw

    SShaw Member

    Fluke is a good brand. Can't go wrong with that. I've got a Fluke 117 meter for basic electrical stuff. It's solid.

    Most clamp ammeters don't measure power, are geared towards large amperage, and don't have very good resolution. The Fluke 345 power meter is $3K, so I don't have that. The ammeter I settled on is a new one, the Supco®-Redfish iDVM 550 Wireless Clamp Meter. It's made in China, but seemed to uniquely have the features I wanted and was reasonably priced at $289.
     
  17. gsmith22

    gsmith22 Member

    had to put heat on a few days back overnight and watched the fan ramp up/down. I can confirm that for the same reported fan speed (ex F5 in cooling vs F5 in heating) it uses a larger amount of energy during heating than cooling confirming that the fan is in fact being slowed down during cooling. Also, I can confirm that the fan CT can't seem to measure wattage below 40W even though I suspect some of the speeds in cooling (1-5) and some in heating (1-3) are probably below 40W. All of these fan speeds show 40W being used . I checked out the supco-redfish clamp meter and I can see what you are now talking about - its an HVAC specific meter that basically does what the Fluke 345 does at a substantially lower price point. Fluke 345 seems to be geared for far higher currents too. Some used Fluke 345s have sold on ebay in the sub $1000 range but that is still a crazy amount of money to spend on a meter if this isn't your day job. I am probably going to own that supco-redfish meter at some point because of its features without breaking the bank. thanks for the recommendation.
     
  18. SShaw

    SShaw Member

    You are welcome. Thanks for the update. I wonder whether WF adds a small minimum value to account for the power used by the transformer and control boards.
     
  19. geoxne

    geoxne Active Member Forum Leader

    Just a shot in the dark here. The wiring schematic notes that the fan power wire is routed through the CT sensor 2 times. If not wattage would be under reported.
     
  20. SShaw

    SShaw Member

    I saw that too. I checked mine and it's looped through the CT twice.
     

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