Heat Pump Standby Power Use

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kiwichick12

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#177585 7-Aug-2015 15:37

Hi all,

Just wondering if anyone knows how much power a heat pump on standby would use? i.e. how much power does it use when you've switched it off with the remote, but not flicked the large power switch located outside.

I'm sure power use by the heat pump is minimal, but am still interested to know (it's a very old, inefficient one - 12 years+ I think), and as it's internally wired I can't just plug in a power meter. I've searched online but can't find anything besides this table summary. It mentions air conditioners (it's American), but I'm not sure if that would be equivalent to our heat pumps or not.

http://standby.lbl.gov/summary-table.html

Thanks!

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#1360732 7-Aug-2015 15:50

My underfloor (air-to-water) heatpump draws about 45W when it is *off*. For that reason I switch it off at the wall (external isolation switch) at the end of winter as 45W for 24/7 adds up!

Not sure about normal air-to-air units.

kiwichick12

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#1360741 7-Aug-2015 16:07

Wow that's a lot! I hope regular ones don't use that much.

Batman

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#1360805 7-Aug-2015 18:01

i want to know too!

JayADee

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#1360834 7-Aug-2015 18:51

Well damn, I didn't even think of that. Now I also want to know!

Geektastic

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#1360845 7-Aug-2015 19:11

I found an info sheet for a Fujitsu split unit that listed standby use at 9 watts.

timmmay

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#1360923 7-Aug-2015 21:29

My UPS uses 15W when it's turned off. I've never measured my heat pumps, you'd need a clamp meter or something. I might turn them off in summer too, but then we use them for air conditioning.

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#1360936 7-Aug-2015 22:23

timmmay: My UPS uses 15W when it's turned off. I've never measured my heat pumps, you'd need a clamp meter or something. I might turn them off in summer too, but then we use them for air conditioning.

Ditto. I doubt that there are more than 30 days a year when ours are not working one way or the other for at least part of the day or night.

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kiwichick12

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#1360938 7-Aug-2015 22:34

I'm surprised they don't all have to state their idle power use somewhere in the heat pump specs, considering power usage:heat output is what they're graded on. 9watts per hour equates to 6.48kwh per month (based on 30 days) if idle the whole time. Or around $1.70-ish, $20+ a year. Not much, but still money wasted; and when you add it to the idle power use of other devices, it sure adds up.

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#1360945 7-Aug-2015 23:30

kiwichick12: I'm surprised they don't all have to state their idle power use somewhere in the heat pump specs, considering power usage:heat output is what they're graded on. 9watts per hour equates to 6.48kwh per month (based on 30 days) if idle the whole time. Or around $1.70-ish, $20+ a year. Not much, but still money wasted; and when you add it to the idle power use of other devices, it sure adds up.

Meh. It's just money.

KGM

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#1360990 8-Aug-2015 08:13

I have a Mitsubishi Unit. It Draws 0.7A while not running.

P = VI
= 230 * 0.7
= 161W

Multiply this by 24 hrs to give the daily power usage..

24*161 = 3864W
=3.86kWhr / day

Power Consumption for Jan was 122.37kWHr, Feb 114.71kWHr & Mar was 125.69kWHr. The only runtime during that period was for 33 minutes in Feb.

Having now accumulated the data for a calendar year to get a base line, I will be turning off the heat pump at the isolator for the summer months, where I am not using it.

I am told that the majority of the power consumption is due to the crankcase heater & not the electronic controls of the heat pump. Refrigeration engineers may be able to advise on this.

kiwichick12

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#1361015 8-Aug-2015 09:35

3.86kWh a day? That equates to ~ $30 month! I'd definitely be keeping that sucker turned off.

timmmay

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#1361037 8-Aug-2015 09:48

Anyone know what a Nocria Awtz24l uses? How about a Daikin FTXS60FVMA?

jmh

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#1361041 8-Aug-2015 10:08

Gosh, you add that to the cost of HRV, and constantly broadcasting phones and wifi, it's no wonder my power bills are so high.

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#1361437 9-Aug-2015 10:41

If anyone does decide to turn off the heat pump at the isolator for an extended period of time, make sure that before using the heat pump again, you comply with the minimum amount of time (up to a full day) indicated in the manual for the crank-case heater to warm up the compressor otherwise damage can occur to the compressor. In most cases the warranty will be voided if you don't follow those minimum guidelines.

Also make sure that the unit has been thoroughly dried by using the heat mode for an hour or two, before decommissioning.

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#1361482 9-Aug-2015 12:17

kiwichick12:(it's a very old, inefficient one - 12 years+ I think),

When did you last have it serviced? I highly suggest that you do then when the electrician comes to check it out you can ask them to check how much it's drawing when idle. If they're good they'll likely try to sell you on the benefits of upgrading to a modern inverting unit (yours probably just turns off and on to maintain a temperature rather than trickling heat) to which you can consider or politely decline ...

You're not on Atlantis anymore, Duncan Idaho.

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