WaterFurnace energy monitoring not accurate

Discussion in 'General Discussions' started by Michael Cohen, Aug 19, 2016.

  1. Michael Cohen

    Michael Cohen New Member

    I have a new installation of a 4 ton Series 7 system with Aurora Advanced Controls. The energy monitoring isn't even close to being accurate, and I'm looking for information on whether this is a problem with WaterFurnace in general, or an unusual situation with the equipment we have.
    I see a couple of current transducers (CTs) used in the system - one for the blower, and one for auxiliary heat. Don't see any transducers used to monitor the variable speed compressor nor for the loop pump. WaterFurnace shows 3 CTs in their documentation. I wouldn't think they would rely on a table lookup to approximate the compressor currents as current transducers are relatively cheap, and the board appears to be set up to handle additional CTs.

    WaterFurnace uses the Symphony platform to provide energy data.
    I have attached a table showing a few current readings I took at different compressor and blower speeds - Symphony reports the power (watts) used by the system, so I calculated the current using 240 vac - actual voltage is around 245 vac which makes the discrepancy worse.

    Energy Monitoring variances.jpg

    Anyone have any experience with the WaterFurnace energy monitoring? This shouldn't be a tough task to do - is this inaccuracy normal for WaterFurnace?
    Any insights would be appreciated.
     
  2. urthbuoy

    urthbuoy Well-Known Member Industry Professional Forum Leader

    Are you measuring the current on the same wire as the current transducer?
     
  3. geoxne

    geoxne Active Member Forum Leader

    An ammeter measures apparent power not true power (as read by your electric meter for billing) on an inductive load. A power factor must be applied.

    On setup with the AID tool input voltage needs to be in put. Power Factor can also be adjusted.

    If electric heat was installed the transducer for Aux and Fan must be installed per factory instructions.

    Loop pump has no transducer. Its power is approximated by software based on the pump system chosen in setup.
     
  4. Michael Cohen

    Michael Cohen New Member

    Thanks for the quick response - The setting via the AID tool was set to the 240 vac. I don't recall whether the installing company changed the default setting for the power factor, but will check into it. The electric strip heaters were not connected, and the blower wire was wired through the CT.

    When I look at the power company's electric meter, prior to starting cooling, and after cooling the delta is in line with the reading I see on the digital ammeter.

    For example, when I look at the power company meter, I was seeing an increase in power usage of ~1Kw when the compressor was in stage 1 (C-1), and the blower was running at SPD-4. The clamp on ammeter was reading 4.38 Amps which would be just over 1KW (4.38 * 240). The WaterFurnace Symphony was reporting 474 watts - Personally, I like the 474 watts :), but reality is our utility company will say we are using twice that amount.

    For what it's worth, I have no problem with the loop pump being estimated, as any variance would be fairly negligible - only included it for completeness.

    I will check the PF setting, but would expect it doesn't solve the issue - since the variance changes drastically at different compressor stages.
     
  5. Michael Cohen

    Michael Cohen New Member

    I am looking at one leg of the the line going into the heat pump, and comparing it to the amount the Symphony platform says is the "Total Unit Energy". There isn't a CT on the line coming into the unit - as far as I can see there is only a CT which is measuring the blower current, and a CT which is not being used (for the strip heater).
     
  6. geoxne

    geoxne Active Member Forum Leader

    Correction
    Power factor is adjusted on single and dual capacity units with Energy Monitoring.

    On the VS Series7 the current sensors must be internal to the VS Drive and PF calculated by software.
     
  7. Michael Cohen

    Michael Cohen New Member

    In either case, wouldn't you expect the reading on Symphony to match (or be relatively close) to the utility's electric meter? Plus, would you think the 474 watts is a bit low for Cooling stage 1 with fan on speed 4? Also, I would expect the difference to be more consistent. The range of variance between measured (ammeter) and reported (Symphony) from 44.9% to 62.5%.
     
  8. geoxne

    geoxne Active Member Forum Leader

    4 Ton WF Series7
    4TSpd1Fan4Cool.JPG
     
  9. Michael Cohen

    Michael Cohen New Member

    Thanks for the feedback - When you compare this to your power company's meter, does it agree? I found when I looked at the meter prior to the cooling starting, and after it started the power changed on the utility's meter was over twice what Symphony reported.
     
  10. geoxne

    geoxne Active Member Forum Leader

    There is no way to read instantaneous power on my meter. The big disk in the center spins and the digit dials turn over time. The occupants of the house would not agree to turning everything else off in the house for an hour to read results.

    How does your power meter work? And how do you read power in use? Has your power company found a way to charge for imaginary power?
     
  11. Mark Custis

    Mark Custis Not soon. Industry Professional Forum Leader

    Billing is why they paint the rates and costs with inadvisability paint. The first liar does not stand a chance to win the contest.
     
  12. Michael Cohen

    Michael Cohen New Member

    Some people are picky and not willing to go the extra mile for science:). Would be tough to get good resolution going with the analog meters, especially if the thermostat turned off cooling for a period of time during the "test".

    The utility in our area uses meters which display voltage, realtime power, and accumulated power. It would be tough to know without the realtime power display - I would most likely just trust the numbers Symphony provides.

    Thanks for the additional info.
     
  13. Mark Custis

    Mark Custis Not soon. Industry Professional Forum Leader

    It is possible to buy a meter that will mimic the provider's style. It could be hooked up to the machine only. You would have power usage and then would need to extrapolate delivery and fuel charges, after all had been sprayed with that paint.
     
  14. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader

    Number the symphony is reporting seem to fit well. We used the watts node power meter and found the energy numbers within 3% when setup correctly.

    But I would check the blow speed setup, you seem to waste a lot of energy
     
  15. Michael Cohen

    Michael Cohen New Member

    There are a couple of issues, and the one I was focusing on is whether the Symphony numbers are accurate. The second area would be whether the performance is reasonable.
    I haven't seen good correlation between the Symphony numbers and what I see on either the ammeter or the utility's power meter, but can skip that for now and look at performance. I wouldn't have a problem with 3% correlation, but I'm not seeing anything close to that.

    What are you seeing when you say a lot of energy is being wasted? Are you basing it on the Symphony values (474 W), or the ammeter readings? What would you expect power usage for the compressor, fan and loop pump for a well configured system?

    The complete breakdown for the lowest cooling stage (C-1, Fan motor 4) on our system is:
    Compressor 344, Fan 85 W, Loop Pump 45 Tot 474

    Are these numbers higher than what you typically see for the compressor and fan speeds?

    You mention you are within 3% when setup correctly. What does setting things up correctly mean? Things like setting blower speeds for optimum heat transfer, or setting the Waterfurnace parameters to reflect the installation correctly (i.e., line voltage 240 vac, etc).
     
  16. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader

    Compressor is fine, but fan and pumping power is too high. You are using 30% for fan and pumping power. Lower your pumping speed and fan speed.
    Unless you pressure drop for ductwork and loop is high.

    Pump is set to 30% min and 75% max. Fan is set speed 2 for LOW COMP and speed 8 for HIGH COMP. We see 16 watts for the pump and 40watts for the fan for a 4 ton 7 series in comp 1 stage.

    The way the compressor drive works is that you cannot just multiply Volts x Amps. There are Power Factors and other factors you need to adjust for. The unit is not drawing 1.48 when not running.

    In the example below the loop is at 64F EWT and entering air was 79F. Thus the compressor runs more efficient than in your example.

    Just took a screen shot for you to see the blow and pump setup.
     

    Attached Files:

  17. Michael Cohen

    Michael Cohen New Member

    Thanks for the additional information. The 1.48 amps is the ammeter reading when in fan only mode, and running at speed 5.
    I understand the inductive load of the compressor, fan and pump will result in a volt x amp calculation deviating from the demand the power company "sees".
    Unless I'm missing something, the Symphony reading for total power should reflect directly to the utility's power meter reading. In other words, if the heat pump turns on and uses 474 watts, the utility's meter reading should increase by 474 w, not the approx 2 times that amount.
     
  18. Michael Cohen

    Michael Cohen New Member

    Thanks for the additional information. The 1.48 amps is the ammeter reading when in fan only mode, and running at speed 5.
    I understand the inductive load of the compressor, fan and pump will result in a volt x amp calculation deviating from the demand the power company "sees".
    Unless I'm missing something, the Symphony reading for total power should reflect directly to the utility's power meter readin.
    Even when I ignore the ammeter readings, the increase in the reading on the utility's power meter when the heat pump started in the cooling mode was close to 2 times what the Symphony readings indicated.
    After sleeping on the info you provided, I had additional questions. The system is running at higher fan and most likely higher loop flow rates - don't know what the setting for the loop pump is, as I wasn't watching them when they configured the system with the AID tool. It would seem that running at a higher blower fan speed would provide a quicker heat transfer than at lower speeds - may not be more efficient, but could see that the compressor would have more off periods with this higher fan setting. The other thought is in rooms with cathedral ceilings, the air will mix better at higher fan speeds, and more likely to have the cool air reaching the floor, rather than "sitting" at the upper elevations.
    It looks like the VS system requires a change in thinking - system run longer, but at speeds which make it's operation less noticeable. Are there any "good practices and guidelines" that help someone new to the Series 7 understand how to configure the system, and make reasonable decisions on any tradeoffs that might exist?
    Thanks again for the guidance.
     
  19. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader

    Cool air is heavier than warm air, so the cool air will always settle at the bottom. But yes, higher fan speed can mix air better.
    The compressor will always transfer the heat. You gain slightly by increasing your fan and pump, but it will cost you much more in electricity to do so. In your case running in 1st stage, your fan and pumping power added 30% to the overall system energy use.
    In terms of discrepancy between meters, keep also in mind that the 7 series starts up in stage six first to circulate the oil in the compressor, and then refs to the desired stage after a minute or two. You might have caught it during that time.
    Indeed, the 7 series changes everything from system design standards to setups.
    With the symphony I usually go in after the commissioning and optimize the system. You can very quickly find the sweet spot where the system provides the most efficiency without compromising the capacity.
     
    Last edited: Aug 21, 2016
  20. Michael Cohen

    Michael Cohen New Member

    Possible what I'm seeing a higher startup if it spans a minute or two - I'll look at it again for a longer duration - I wouldn't have "stayed with it" for more than a half minute, so worth rechecking.

    So, you'd suggest just playing with the fan and pump speeds, and observing the power the fan, compressor, and loop pump uses? Would you look at how EWT and Supply Air temps to see if a change in fan and pump speeds improves or makes things worse?
    Do you bump up the air speed in the winter?
    Thanks again for the guidance.
     

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