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Community and Q&A

Mini-split phantom load

User avatar
Elden Lindamood | Posted in Mechanicals on

I’ve been monitoring my electrical use with a TED monitor in my main panel. I’ve isolated a number of circuits to develop a sense of where my energy is being used. I recently confirmed a suspicion and would be curious about other peoples experiences and thoughts on it. It is in regard to my mini-split, and the energy it uses on standby.
I installed a ducted Fujitsu 12RLFCD unit for heating and cooling. In the month of June, 2017, I had the system set to off for the entire month. No heating, cooling, ventilation, or anything. I didn’t throw the breaker, but I shouldn’t have to. When I collected my electrical usage data for the month of June, the mini-split had consumed 22.8 kW. I don’t know what to call this other than a phantom load. That 22.8 kW accounts for almost 7% of the usage for the entire house for the month (326 kW), and I have an electric range and water heater. This raises the following questions in my mind.
Is this normal?
Is it considered acceptable?
Is it factored into the efficiency ratings for the unit?
Is this information generally published in the manufacturer’s specs so I can compare units and select one that uses less energy on standby for future projects?
Thoughts are appreciated.
Elden

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Replies

  1. User avatar
    John Semmelhack | | #1

    That's about 30W continuous. That's certainly higher than it should be. I have a ducted 9RLFCD installed at my house. Power input is about 8-10W when off or while waiting for a call for heat/cool.

    I suggest confirming the power reading is correct by comparing to another device, such as a clamp ammeter that can measure true power (such as: https://www.trutechtools.com/3729961). I'm pretty sure TED monitors measure true power, but it's possible that it's just measuring A * V (amps times volts) without a power factor correction.

  2. User avatar
    Dana Dorsett | | #2

    TED devices all correct for power factor- I'm not sure if there is a mode where that can be turned off. (Don't own one myself, haven't played with them too much.)

  3. Anon3 | | #3

    The Japanese mini splits have fallen behind on techs. Plus they are overpriced. The Midea Premier standby is 1w for example.

  4. User avatar GBA Editor
    Martin Holladay | | #4

    Elden,
    The issue comes up every now and then on GBA, and misunderstandings about power factor are often part of the puzzle. But you may want to get a manufacturer's rep to investigate if you are sure that your readings are correct.

    Here are some comments that I posted on an earlier thread called Disappointing phantom load on 27.2 SEER Fujitsu 9RLS2 minisplit:

    "I just sent an e-mail to Marc Rosenbaum (who has a Fujitsu minsiplit) to ask him what he knows about his unit's phantom load. He responded, 'Mike Duclos has data on this, and some info about how the power factor is really bad when the unit is in standby, so that the apparent W aren't the true W. My system didn't show this level of usage as far as I know - I have a old style glass-front [kilowatt-hour] meter on it, and when it is turned off at the remote control the disk doesn't spin. My experience is that usually loads of 30W or more make the disk spin - 80W would be a lot of power for the utility to give up. This past winter, more normal than the first winter I have full data on, my house used 1,462 kWh for heat over a 6 month period. How much is standby I don't know.'"

    "A follow-up e-mail from Marc Rosenbaum: 'By the way, I have quite a number of days when the meter [connected to the Fujitsu minisplit] read zero additional kWh over the previous 24 hours. This of course could be that the meter can't read low watts, but 80W continuous is 2 kWh/day.'"

    "I just spoke with Jason Cruze on the technical help line at Fujitsu. He said that the maximum phantom load for the Fujitsu 9RLS2 is 0.1 amp. At 240 volts, that's 24 watts. If anyone is measuring 80 watts, Cruze recommended calling a technician to find out what's wrong with the unit. He said that there is no heater or freeze protection on the 9RLS2. (However, there is a heater on the Fujitsu 15RLS2H, so one would expect the phantom load of that unit to be higher in cold weather.)"

    "I just received an e-mail from Mike Duclos. Mike wrote, 'I’m not sure about which model the 80 watt phantom load was measured on (I haven’t looked at the thread), but I’d suspect measurement technique. I ran into this with the first generation eMonitor at the Montague PowerHouse, which has a Fujitsu 9RLQ – when I first hooked up the eMonitor, I saw [a phantom load of] 90 watts plus continuous. Long story short, I contacted Bill Hick, Fujitsu NE sales manager, who quickly referred me to someone from Fujitsu on the west coast who had already been through this with another eMonitor user. Power House Dynamics, maker of the eMonitor, had an issue with their power factor correction circuit which they subsequently fixed, and retrofitted to old units (including mine) N/C.

    "'Following that, I was seeing very low power (near zero, measurement accuracy at very low power levels may have been a factor) up to about 20 watts intermittently during standby. ... If the people doing the measurement don’t understand about power factor, that could easily be the problem. FYI, Power House Dynamics has been incredibly supportive when I’ve had eMonitor power factor questions (you may recall the infamous induction cooktop), even lending me a pricey power factor meter for some measurements that confirmed what I had documented with an oscilloscope.'"

  5. User avatar
    Elden Lindamood | | #5

    Thanks all. I'll seek confirmation on the circuit draw to cross check the TED. I'll look deeper into the power consumption graph and try to determine if the draw is intermittent or constant when the unit is on standby.

  6. Jon R | | #6

    I agree with verifying that it is real. TED claims accuracy of 2%, but of what? Full load - that could be hundreds of watts.

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