Bloody reverse-cycle air-conditioners!

by jasonp on

First the first time in, forever, I had the house to myself for a few hours, which gave me the opportunity to have a crack at determining the cause of my phantom load.

My phantom load hovers between 450 and 600W, and I've not been able to figure out why for some time. I've used my Flukso to assist in finding likely cuplrits, like TVs on standby, microwave ovens, wall-warts etc, but the last 500 Watts has had me at a loss for some time.

Today with the wife and kids out of the house I plugged my flukso and my router into the UPS, and turned everything off at the main switchboard. Using my tablet, and watching the "minute" feed on my flukso, I merrily flicked circuits on and off until I figured out what was drawing the last few mysterious Watts.

No surprises:

  • The house main 9kW Reverse-Cycle AC (Fujitsu): 250 Watts just sitting there! It gets a good workout in summer, but for winter we use a wood heater, so I can turn if off for at least half the year. That's $375 immediate saving! I understand that RC aircons need to ensure the gas doesn't liquefy, but 250 Watts - all the time?!
  • Was also surprised that brand new wall-mounted reverse-cycle AC (Panasonic) pulled 50W. Not sure what to do with that as the kids use it for heating/cooling whenever they are in the rumpus room. FYI we have an old (6 years older) Daikin RC AC in the family room - it has no phantom load. +1 for Daikin.
  • The old fridge in the garage pulls 285 Watts. Not sure what the duty-cycle, but I don't think it's great. Might be time to convert a chest freezer into a fridge
  • The bubbler on our AWTS septic pulls 225 Watts and has a pretty hefty duty cycle. I don't recall ever hearing that thing turn off. I think I could wire it up to an Arduino or a RaspberryPi to reduce the duty cycle to something more acceptable than 100%

I think the Flukso has already paid for itself a few times over. Now it's given me some ideas of more savings, and more projects.

Cheers,
JasonP

‹ Partial solar eclipse March 20, 2015 Analysis of Flukso data ›
bazzle's picture
bazzle |

I put a plate mounted 25amp isolating switch on my rev cycle low on the wall in the room its used in.
It has a neon light in the switch so I know if its left on.
When we use it we turn it on and wait 15 mins or so before switching on with the remote to allow the unit to stabilize. Been that way for a few years now. (Mitsubishi inverter)
Same with my home theater. I use a wireless "Future switch" with the switch pad on the wall near the main light switch bank.

davida's picture
davida |

I went through the same process recently. But I think you will find these are not real loads. The problem is that these devices have varying power factors so the current and voltage are out of phase. This means the power readings are bogus. You need to measure the real power consumption at the meter.

jasonp's picture
jasonp |

those readings were at the meter.

davida's picture
davida |

You mean these were not measured using the Flukso current clamps but real meters?

jasonp's picture
jasonp |

no, i misunderstood you. i did use the flukso current clamps. i'll have to do reading up on power factor and how it impacts my flukso readings...

jasonp's picture
jasonp |

thanks gebhardm. next time the wife and kids are out i'll make similar measurements, but also check the meter. (It's the old spinny-disk type, where one rotation is 1/400th of a kWh). I should be able to calculate power factor that way, yes?

bazzle's picture
bazzle |

That meter will show "real" power consumed. I use DIN rail kw/h meters to supply pulse to Flukso.
Aircon on standby issue's are real. Some have an ~200watt sump heater. Been written about on a few trade forums.