Air conditioner "standby"

The greenest watt is the one you don't have to create. Energy efficiency is the low hanging fruit of greening our homes. Ask your questions or post your energy efficiency tips in here!

Air conditioner "standby"

Postby zzsstt » Tue Dec 29, 2009 5:55 pm

Having acquired a Wattson a while back, I have been investigating the energy use in the small cottage where I fitted it.

After a few days of detecting "energy leaks", I found I still had about +/-140W of unexplained consumption. Removing this required a trip to the switchboard, where I discovered the power drain was to the three air conditioners. These are small "split system" reverse cycle units (current models from a big name brand) that are used on hot nights over the height of summer and at night through the coldest part of winter. For 6 months of the year - spring and autumn - they are never switched on.

My investigations have revealed that these units, even when "off", draw a residual "standby" of perhaps 50W each. After speaking to the manufacturers, I have discovered the reason is that they have to maintain a minimum temperature of the refrigerant at all times. If the fluid becomes too cool, it increases in viscosity and can damage or severely reduce the life expectancy of the compressor if it is started in that "cold fluid" situation. As a result, in order to be ready to be "instantly activated" the units have a small heater that constantly maintains the fluid temperature.

The advice from the manufacturer is that it takes at least 6 hours for the unit to warm the fluid sufficiently to allow a safe start, possibly slightly less on a hot summer day and probably more (ideally 12+ hours) in winter when the unit is very cold. However, to save this constant 50W draw, the air conditioners can be switched off at the switchboard AS LONG AS THEY ARE ALLOWED TO WARM UP FOR AT LEAST 6 HOURS OR PREFERABLY OVERNIGHT BEFORE THEY ARE ACTIVATED.

In my situation, I can save at least $100 a year by powering the three units down at the switchboard for spring and autumn!

I hope this information will benefit someone else too!
zzsstt
Solar Crusader
Solar Crusader
 
Posts: 1296
Joined: Fri Oct 02, 2009 3:27 pm

Re: Air conditioner "standby"

Postby Helipos » Tue Dec 29, 2009 9:48 pm

Perhaps a brand of aircon and model would be helpful here.
Cam
User avatar
Helipos
Solar Crusader
Solar Crusader
 
Posts: 305
Joined: Tue Oct 06, 2009 10:18 pm

Re: Air conditioner "standby"

Postby zzsstt » Wed Dec 30, 2009 8:31 am

Helipos wrote:Perhaps a brand of aircon and model would be helpful here.
Cam


From the way it was described to me, this is fairly standard behaviour for all modern (we did not dicuss older models) refridgeration style air conditioners, which was why I did not bother to include a model or brand. These particular units are Daikins, however, and it was Daikins technical support team that provided the information.
zzsstt
Solar Crusader
Solar Crusader
 
Posts: 1296
Joined: Fri Oct 02, 2009 3:27 pm

Re: Air conditioner "standby"

Postby kalindriel » Wed Jan 06, 2010 11:43 pm

Thankyou.
I have often wondered about the standby use of the airconditioner that our house had. Now I know how to turn it off safely and save the energy.
kalindriel
Solar Evangelist
Solar Evangelist
 
Posts: 57
Joined: Wed Dec 09, 2009 12:34 pm

Re: Air conditioner "standby"

Postby munter » Thu Jan 07, 2010 1:01 pm

Interesting find zzsstt. It would certainly be worth saving a constant draw of 150 watts from your power bill. Some validation from consumers of manufacturers that other brands also have a similar power draw would be useful to ensure it isn't a case of one manufacturer mischievously advising that their unit is no worse than any others.
For reference - I have a mitsubishi unit in our house and I find that the billing meter dial does not rotate when I have all other circuits switched off and just the AC circuit left on and the AC in standby. This suggests minimal (or at least low) power consumption. I'll have to check what kind of consumption one spin on the dial represents to see if I can determine the sensistivity of the billing meter.
http://renovations08.blogspot.com/ - my energy efficiency blog
munter
Solar Crusader
Solar Crusader
 
Posts: 191
Joined: Thu Oct 08, 2009 12:39 pm
Location: Sydney

Re: Air conditioner "standby"

Postby Smurf1976 » Thu Jan 07, 2010 11:03 pm

munter wrote: I'll have to check what kind of consumption one spin on the dial represents to see if I can determine the sensistivity of the billing meter.

Typically it's either 400 or 266.6 revolutions of the disc per kWh (at least that's for the meters we use in Tasmania). It normally says on the front of the meter somewhere what the revs / kWh figure is.

As for sensitivity, I haven't tested it but I've always understood that standard single phase rotating disc meters can record anything above 2 watts consumption and will thus, in practice, record all energy consumed since most households have a minimum load of no less than 4 watts and in most cases far higher.
Smurf1976
Solar Crusader
Solar Crusader
 
Posts: 937
Joined: Mon Oct 26, 2009 12:56 pm

Re: Air conditioner "standby"

Postby greenfan » Sun Jan 10, 2010 6:22 am

Ah, this explains the "Crankcase Heater (yes/no)" column for air conditioners on energyrating.gov.au and the obscure comment in my Airwell's user manual that it burns 45W on standby.

Does anyone know if the "Dirty Filter" warning light needs continuous power to count the hours that the fan is running?
greenfan
Solar Supporter
Solar Supporter
 
Posts: 1
Joined: Sun Jan 10, 2010 5:53 am

"STANDBY" Power

Postby Tracker » Sun Jan 10, 2010 9:38 am

.
As a generalisation, most of the normal split Air-Conds that we see, do not have case heaters.
I have only seen them on some larger US products, where Sub-Zero is the norm.
Being in Sydney, that might bias what I see..
Were I at Cradle Mountain or Jindabyne , it might be different.

Needless to say, if your RAC (Reverse-Cycle Air Cond.) is turned on by a remote control, then it does draw power on standby, just like every other "Electronic" appliance. How many people actually turn their Fisher-Paykel washer off when not in use ? If you have one, feel the warmth in the control head !

If you did have a case-heater in a bigger unit, I don't think I would hesitate to disconnect it , in any but the colder areas of Australia.
In the least, you could fit a new switch, so that you could disable it in summer, and turn it on an hour before using the RAC in winter.

Something to watch, for those who have the big 2 door refrigerators...
Many have Mullion-Heater... Door Jam heaters, intended to warn the metal at the seal..
The fridge-freezer is real cold on the inside.. The cold is transmitted through the skin at the seal and for an area near the seal, it gets cold.
On humid days, condensation forms and will even run to the floor forming pools.
The heater is designed to selectively heat these area of possible condensation.
Problem is that they typically draw 60 to 100 watts -- Continuously !
Most fridges use the hot-gas from the compressor to do the same job, but as I said , some of the yank products still have them, and have a small switch inside to disconnect it for low humidity times.
Be sure to turn it off , for as long as you can.
.
.
Tracker
Solar Crusader
Solar Crusader
 
Posts: 4766
Joined: Wed Sep 23, 2009 6:54 am
Location: SYDNEY --- EA - Network, Retailer - EA

Re: "STANDBY" Power

Postby Smurf1976 » Sun Jan 10, 2010 1:28 pm

Tracker wrote:.How many people actually turn their Fisher-Paykel washer off when not in use ? If you have one, feel the warmth in the control head !

Always switch mine off (always...). Left on, the electronics stay running 24/7 and fail within a few years, meaning you either pay a relative fortune for a new control board or scrap the whole machine. Much cheaper to just turn it off.
Smurf1976
Solar Crusader
Solar Crusader
 
Posts: 937
Joined: Mon Oct 26, 2009 12:56 pm

Re: Air conditioner "standby"

Postby munter » Mon Jan 11, 2010 1:35 pm

As mentioned by greenfan, the detailed spreadsheet available at energyrating.gov.au shows which models have a standy heater and which don't. Mine doesn't have a heater but then with a little sorting of the filter I did see that there are models with higher COP effieciency than the model I had installed last year. I think I will make more use of the energyrating website *before buying appliances* in the coming years...
http://renovations08.blogspot.com/ - my energy efficiency blog
munter
Solar Crusader
Solar Crusader
 
Posts: 191
Joined: Thu Oct 08, 2009 12:39 pm
Location: Sydney

Next

Return to Energy Efficiency

Who is online

Users browsing this forum: No registered users and 2 guests