Recently installed a medium sized Air Conditioning Split System from Daikin. Very happy with power consumption when running, surprisingly efficient. However I found a nasty surprise when monitoring the standby power consumption. Turns out the system has an inbuilt heater to maintain the temperature of the oil in the compressor. This heater in my tests turns on whenever the outside temperature drops below 15 degrees. I live in an area where the overnight temperature gets well below this level for most of the year, and of course in winter we often don't even reach that during the day. The heater draw on my power meter is 150 watts. I queried this with Daikin. First they said my meter was faulty, but admitted according to specifications it is around 100 watts. Whichever value you accept, my tests or their claims, it is still a significant power use on standby and tends to negate the running efficiency. I would urge anyone considering the installation of an Air Conditioning system to check carefully with the manufacturer, you could be in for a nasty bill shock.
Excessive Power Consumption of Air Conditioners on standby
(27 posts) (9 voices)-
bcgraham
MemberI did a lot of research into systems before making a purchase. I found no specification available for standby power consumption, and did not expect such high readings. I would surmise that the only way to find out would be to direct the specific question to the supplier/manufacturer. I found my supplier/installer was completely unaware of this hidden consumption, and had to refer me to the engineering people at Daikin. It verges on a breach of consumer laws that it is not disclosed before purchase.
Posted Monday 27 Nov 2017 @ 4:45:03 am from IP # -
Johnnojack
MemberI had this discussion with my supplier when we had a Daikin installed. He was aware it had a crankcase heater but could not say what power it used. We went away for a few weeks and turned off everything except the smoke alarms, or so I thought as I forgot the a/c. House used about 1kwhper day and I couldn't figure it out until I saw the isolating switch outside in the on position. I agree it's not a good design feature for a supposedly very efficient device. Why can't they use an oil in them which only need to be kept above say 5deg. A minimum of 15 means it will be on more nights in a year than it is off, (in southern states that is) Another point is I am not sure if turning the machine off will damage anything if it gets frosty while I'm in sunny Queensland during winter. So little info around on this.
Posted Tuesday 28 Nov 2017 @ 2:50:44 am from IP # -
Lance
Key MasterIt's not uncommon to just turn the unit off at the breaker if you are not going to use it for a while, just turn it back on at least 6 hours before you want to use the aircon.
But, I agree that the standby consumption is way too high, I think if they can't design a compressor that doesn't need its oil heated almost constantly, then they need to try harder. At the very least, the standby consumption should be clearly stated in brochures etc, and it should absolutely be taken into account in energy ratings (it may be already, I don't know).
Posted Tuesday 28 Nov 2017 @ 4:36:15 am from IP # -
bcgraham
MemberThe problem is overnight. In inland areas where the temperature drops overnight it is not unusual for the unit to use 1kw of power on standby, every single day. The only way to prevent this is to turn off the supply to the unit at the switchboard. Not nearly good enough.
Posted Tuesday 28 Nov 2017 @ 4:43:37 am from IP # -
Morbo
Memberdayteime in the 20s and at nicht below 15 and you need an aircon? I guess the 100W standby would be your smallest problem. This kind of temperatures would be 20 deg in my weatherboard.
My split systen uses an extra 1kWh per day. So for about 360 days a year its switched off. But I have fans and dont live in a tent.Posted Tuesday 28 Nov 2017 @ 10:00:16 am from IP # -
Annette
Memberbcgraham said:
Recently installed a medium sized Air Conditioning Split System from Daikin. Very happy with power consumption when running, surprisingly efficient. However I found a nasty surprise when monitoring the standby power consumption. Turns out the system has an inbuilt heater to maintain the temperature of the oil in the compressor. This heater in my tests turns on whenever the outside temperature drops below 15 degrees. I live in an area where the overnight temperature gets well below this level for most of the year, and of course in winter we often don't even reach that during the day. The heater draw on my power meter is 150 watts. I queried this with Daikin. First they said my meter was faulty, but admitted according to specifications it is around 100 watts. Whichever value you accept, my tests or their claims, it is still a significant power use on standby and tends to negate the running efficiency. I would urge anyone considering the installation of an Air Conditioning system to check carefully with the manufacturer, you could be in for a nasty bill shock.What star rating is the Daikin?
Posted Tuesday 28 Nov 2017 @ 10:23:39 am from IP # -
bcgraham
MemberHi Annette
The model I have is rated as 4 star, and is one of the recommended models in recent Choice magazine review of Air Conditioners. I have alerted them to my findings also, waiting to hear back from them. I very much doubt this issue comes into the energy rating figures.Posted Tuesday 28 Nov 2017 @ 11:54:24 am from IP # -
Benny
MemberThats what I was thinking Morbo. If overnight it gets so cool and the house is well insulated, it could get up to 35 the next day and the house should be OK without AC. If its only getting up to high 20's can't the AC be left completely off for a while yet ? Turn on at main supply when they start predicting over 30 max.
Or are you still using it in heating mode because the house is cold in the morning ?
I agree with your main point though that it shouldn't need so much standby.Posted Wednesday 29 Nov 2017 @ 12:04:21 am from IP # -
arttt
MemberI have brought based on Choice reviews before (not an air conditioner) and been shocked by a high standby power. I complained to Choice that they should test this for all products. They dont. Maybe the ATA could work with them to change this.
If you download the full dataset of the energy rating figures from here
http://reg.energyrating.gov.au/comparator/product_types/64/search/comprehensive/?&export_format=csvThere is a column called "avg_pwr_standby_mode" - ignore it as it is no longer used.
You can find the column descriptions here
https://reg.energyrating.gov.au/static/common/comparator/Air_Conditioners.docxThere are 2 more columns that may help you Pnoc and Pnoh.
Pnoc - Non-operative power for cooling mode (lower the better). This is now mandatory and replaces “avg_pwr_standby_mode”.
Pnoh - Non-operative power for heating mode (lower the better) . This is now mandatory and replaces “avg_pwr_standby_mode”.unfortunately the 4 star daikin models all show very low standby power. Maybe the test condition is at a temp above when the heater comes on.
Also you will find in that table various EER/COP values with and without standby power included.
There are some gems to be found here. some are voluntary so not available for all models.
VSCP_EER50
VSCP_COP50
show efficiency at a 50% load. There is quite a few with EER of over 6. It might be worth looking at this rating and picking an oversized model.
H2_COP
shows heating COP at 2 degrees - useful in some climatesPosted Wednesday 29 Nov 2017 @ 12:24:49 am from IP # -
arttt
MemberDigging around a bit i think the Pnoh (Non-operative power for heating mode) is tested at well below 15 degrees C.
I obviously dont have all the information but if you think the model you brought differs significantly from what is found in the energy rating database then im sure the maintainers of that database would like to know as would future shoppers who rely on the star rating to be accurate.Posted Wednesday 29 Nov 2017 @ 1:00:50 am from IP # -
bcgraham
MemberFor the benefit of Benny and Morbo,I live in a well insulated home in an area that experiences a wide range of temperatures. In the depths of -10 in winter the aircon is by a long way the cheapest way to warm my home, cheaper than a wood heater, gas or even hydronic heating. In summer when it is 30+ outside the aircon is a blessing. Plus I have installed a solar system and can run 2 aircon systems at the same time totally on solar, because the running power consumption is so low.
Posted Wednesday 29 Nov 2017 @ 1:53:17 am from IP # -
arttt
Memberbcgraham said:
Thank you for your reply. How do I access the Energy Rating database?The 2 links in my previous post will get you the data as a csv file and a word document that describes the data in the CSV file.
I accessed those by following links from http://www.energyrating.gov.au/
on that same site there is a contact us link
http://www.energyrating.gov.au/contact-ushope that helps.
Posted Wednesday 29 Nov 2017 @ 2:47:08 am from IP # -
Benny
MemberHi bc. I fully appreciate the points you have made last. What Morbo and I were surprised at was that you seem to be complaining about standby power (which I fully appreciate is a problem) at the moment, when you are using the AC in cooling mode (are you ?) but its getting to below 15 overnight and only high 20's in the daytime. We are surprised that you can't completely turn the AC off under these conditions - the house should cool down overnight and stay cool during the day. Unless as I said, you are still using it for heating early in the morning, and so do need to leave it on overnight.
Posted Wednesday 29 Nov 2017 @ 1:41:16 pm from IP # -
bcgraham
MemberBenny you miss the point a bit. Right now my usage is sporadic, so yes it is a simple procedure to shut the unit off at the switchboard. My beef over this as follows.
1. Nowadays we are encouraged to switch off appliances to reduce standby power usage. No one has mentioned Aircon systems anywhere. There was no warning in the specifications for the system that it would use that much power on standby. It dwarfs things like TV's etc.
2. Where I live the internal heater will be running continuously during winter. Unless I shut the power off to the system.
3. If I do that will there be any damage to the system? Daikin have not answered my question about this, but presumably it is there for a purpose, so I would be inclined to think the answer is yes it could.
And finally, Daikin told me that this is typical of most Aircon systems,not just theirs. So all those many thousands of systems are quietly pushing up our electricity bills, and no one is talking about it. Not happy Jan.Posted Wednesday 29 Nov 2017 @ 7:51:43 pm from IP # -
Lance
Key MasterThere can potentially be damage if you turn the unit off at the breaker and then start it up immediately after turning it back on. You need to give the heater time to warm up the oil/crankcase before actually starting the unit. Six hours should be enough under most circumstances.
Posted Wednesday 29 Nov 2017 @ 8:58:48 pm from IP # -
Lance
Key MasterThere's actually a couple of threads on this in the whirlpool forums, see https://forums.whirlpool.net.au/archive/2406245 and https://forums.whirlpool.net.au/archive/2444473
One of ATA's energy people thinks that standby power is included in the energy rating, it is just not separated out in the numbers provided, but isn't 100% sure on that...
Posted Thursday 30 Nov 2017 @ 12:02:48 am from IP # -
arttt
MemberLance said:
There's actually a couple of threads on this in the whirlpool forums, see https://forums.whirlpool.net.au/archive/2406245 and https://forums.whirlpool.net.au/archive/2444473One of ATA's energy people thinks that standby power is included in the energy rating, it is just not separated out in the numbers provided, but isn't 100% sure on that...
yes it is included in the star rating
yes it is separated out if you read the full spreadsheet not the simplified version. See me earlier links.but its only valid in the star rating if it is reported correctly.
Posted Thursday 30 Nov 2017 @ 12:26:41 am from IP # -
Benny
MemberAh now I understand. You were talking about over winter, when heating not now. Thats what we were trying to clarify. Would you ever run the system overnight when it gets so cold ?
This AC standby is something I mention to people when I do home audits, but you're right - its not widely known/publicised. Also another problem is that its hard to measure because split systems are usually hard wired to the switchboard - no plug where you can put a power meter in circuit. I found one house with 3 big AC units and looking at the meter (flashing LED type) it was obvious quite a bit of power being used. We did the test of progressively turning off circuit breakers until just AC one was left, and still 200-300W of standby. Flicked that breaker and 0. My 2 Mitsubishi units seem to have negligible standby but according to the table arttt mentioned its 6W Pnoc.Posted Thursday 30 Nov 2017 @ 7:29:08 am from IP # -
Johnnojack
MemberSix hours! Blimey! When we decide we need some heating is when we decide to turn it on, waiting six hours or anticipating six hours earlier is not very convenient. Sorry Lance no offence I know you didn't decide on that number in isolation. So the heaters are 100watts or 60, how much oil do they need to heat ? Maybe 100 ml? Depending on the size of the machine. Can one place a temperature probe on the thing? Can it be insulated to keep warm? Does it operate on a thermostat? Some have heaters some don't, what? Why? So many questions so few real answers, hullo Daiken, Mitsubishi, Panasonic etc speak up and tell us the truth.
Posted Tuesday 12 Dec 2017 @ 5:02:02 am from IP # -
Lance
Key MasterJohnnojack, six hours is just a decent amount of time for a small heater to heat the entire crankcase, in my estimation, it would depend on each model, ambient temps etc, so six hours should cover it. In many cases, half that time might be fine.
I don't know why they have to have crankcase heaters, other heat pump systems don't need them, look at automotive systems, you hop in the car and turn on the heater and off it goes. While most car heaters use waste heat from the engine, many cars have a fast heat system that uses the aircon as a heat pump for near-instant defrosting (my Subaru Forester has this, see http://www.c-suvs.com/heater_operation-4776.html ) so clearly the compressor doesn't need preheating in these situations.
Posted Wednesday 13 Dec 2017 @ 1:37:48 am from IP # -
Southern surfer
MemberI am planning on installing a Sanden hot water heat pump. Are these also affected?
We already have a Daiken reverse cycle A/C. That’s a lot of standby power consumption.Posted Tuesday 26 Dec 2017 @ 10:51:16 am from IP #
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