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Forum Index : Other Stuff : Off grid air conditioning install.
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Gizmo Admin Group  Joined: 05/06/2004 Location: AustraliaPosts: 5078 |
Recently I moved to part of Australia called the Darling Downs, west of the Great Dividing Range. Before that, I was living in the tropics, on the central Queensland coast. One reason I moved here was to get away from the tropical heat, looking for a milder climate. Should have done my research, since moving here I've experienced the hottest summer days, +41c, and coldest winter nights, -6c, of my life! I wont mention the flies, snakes, flies, lack of rain, and flies. I work from home, spend most of the day at a PC. Hot weather and office work dont mix very well, arms sticking to the desk is very uncomfortable. I also live off grid, with a 220AHr battery bank, 2.1kw of solar, a wind turbine and a 7kW inverter. Until recently I didn't think air conditioning was a option, I couldn't afford one and my off grid system would not have the power to feed it. But a week after Christmas I saw some new split systems on sale at a local hardware store, for half price, marked down from $799 to $399! It was a AKAI, so a cheap rebadged model from China, 9000btu, 2.7kw rated capacity, for a average sized bedroom. Now I always thought the Rated Capacity of a air conditioner was a measure of how much electrical power it used, and 2.7kw is a lot of power to drag out of a small off grid system for any length of time. But I noticed these units also had a Rated Power figure of 680w. A quick google and I learned the Rated Power is the electrical power used, and 680 watts is well within the capacity of my system if the sun is shining. So I bought the AKAI, and set about installing it. The inside unit was easy, installed in my office. I have old fibro ( asbestos ) walls, so instead of drilling into them, I ran the pipes down the wall and through a hole in the floor. The outside unit is mounted directly below the floor. My house is high set on adjustable stumps, so I made a metal frame that hangs from the floor beams, and the unit ended up at head height. I bought just over 3 meters of the refrigerant pipes, with the nuts and flares fitted while I waited, for $50 from a local air conditioning business. I also bought some PVC electrical ducting to hide the pipes, a few bits and pieces, so all up the entire install has cost about $500 including the AKAI. With pipes fitted, and the electrical connections made, I borrowed a vac pump with gauges ( thanks Rusty ), and vacuumed the system down for half an hour. Turned the pump off and the gauge held vacuum for several hours, so looked like there were no leaks under vacuum. Ran the vac pump again for half an hour, then opened one port on outdoor unit ( the split system came pre-gassed ) for a few seconds until I saw 10PSI on the gauges, closed it off and removed the vac pump lines. Next I used soapy water on all the connections to check again for leaks, all good. Opened the ports fully to gas the system, plugged it in and turned it on. After a couple of minutes I was seeing 15c air from the inside unit, room temp was about 32c when I started. Test ran it for 30 minutes. Today was its first real test. Its about 36c outside, I've set the air-con to 26c. Have to say, its pretty nice in my office at the moment. The office is closed up, no real gaps, and the curtains are closed. The air-con compressor is cutting in and out every few minutes, I would guess 3 minutes on, 2 off. While running my total power draw from my off grid it about 1000 watts, and about 300 when off. I'm also running the computer, plus the usual stuff ( fridge, wall warts, etc. ). 1000 watts is well under my solar panel power, so the batteries are going through their normal charge/float cycle. So at this stage its looking like a winner. Time will tell how reliable the system is, since it was a cheap unit, and not professionally installed. But for around $500 I'm pretty happy. Of course my battery bank cant run the air-con at night, but it gets cool here at nights anyway ( it was 17c at 6am, 35c by 10am! ). The AKAI is reverse cycle, so once the sun comes up in winter, it should make my office nice and toasty. Glenn The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
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norcold Guru  Joined: 06/02/2011 Location: AustraliaPosts: 670 |
Go back even 10 years, that`d be not possible, but today refrigeration has made great leaps in efficiency. Not quite as big a leap, bought a new LG 2 door frost free 205l after checking it`s specs, run it down at beach hut with a Honda EU1 inverter generator no dramas, grunts and goes out of eco mode automatically when defrost heater cuts in, reverts to eco mode once timer has cut heater. Runs it for 8+ hours on 2 litres. Cold beer and fast frozen fillets. You got me thinking I have added a air-con room to the gonnado list for next summer. We come from the land downunder. Vic |
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| VK4AYQ Guru Joined: 02/12/2009 Location: AustraliaPosts: 2539 |
Hi Glenn Top marks for that, it is showing we do not have to be dark ages just because we are being off grid, A couple more batteries and a panel or two would make it a real winner. I was hoping to have a geo thermal unit going this year but health has prevented that so it looks like I will go down the split system road for the moment, only trouble the wife wants to turn the whole house into a fridge. 
All the best Bob Foolin Around |
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Bryan1 Guru Joined: 22/02/2006 Location: AustraliaPosts: 1344 |
Yea my mate I sold a heap of 1000ah batteries to installed a 6kw reverse cycle inverter type aircon and the inside of the house is set to 22C, whether it's 26 or 42C outside. I was up there a few weeks ago and had a look at the logs on the outbacks and at no time did the batteries go under 50 volts. He also has a second house for guests with a 4kw aircon and with both going the batteries still stayed above 50 volts. So off grid aircons can be done easily... |
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powerednut Senior Member  Joined: 09/12/2009 Location: AustraliaPosts: 221 |
bugger me. live and learn. I too thought the rated capacity would equal the electrical wattage drawn. Thanks Giz, and all others |
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Downwind Guru Joined: 09/09/2009 Location: AustraliaPosts: 2333 |
You really dont need a set of gauges and vacumme pump to do a install of a split system, as all you need is your nose, and to purge the lines. If you leave the return line nut loose and crack the supply line valve you will soon smell when the line is purged and the gas has filled the lines (it will make you a little light headed when you sniff the gas) Normally there is excess gas in the compressor to suit up to 5-6m of copper tube run so to loose a small fraction in purging lines is quite normal, in fact its how most fridgies i know install these systems by. But they wont tell you that. Stay cool! Pete. Sometimes it just works |
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| M Del Senior Member Joined: 09/04/2012 Location: AustraliaPosts: 155 |
Back in 2009 I bought a portable AC for the boss as it stayed 35 plus for a week or two. Set up a extra vent tube to use outside air for the condenser and only run it when it hits 28 inside. It draws 750w when the compressor is on and 300w when the fans are running. It is a little noisy as everything is inside, but works well. This is it's 6th year of operation and still going strong. The other option was several thousand for a split unit, the portable cost $650, plus a tool trolley and one metal duct($15?). Mark |
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raymond thomson Newbie  Joined: 19/09/2013 Location: AustraliaPosts: 36 |
Nice one Glenn. I have installed a couple of the Akai and similar units using Pete's method quite successfully over the years. Then in building this new house I had all sorts of dire warnings about not using a "professional" to do the work so paid a tradie to do it. Same result though, just more dollars. I chose to put individual units in each room rather than a central system and I reckon it serves us well. We just A/C which ever room we are going to use today and then the bedroom without bothering with spare bedrooms etc. It might be 36 deg today but the reverse cycle is also valuable in winter. Cheers Raymond |
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| domwild Guru Joined: 16/12/2005 Location: AustraliaPosts: 873 |
Pete, Probably the reason for using a vacuum pump is to also get rid of any moisture. A drier cartridge is in the system but will only do so much. If moisture is in the Freon (or whatever they are using these days), then the injector might ice up and stop injecting the liquid. Great to see you, Glenn and others, installing a unit yourself. When I did a bit of work in that field we still had to charge the units ourselves from the F12/F22 bottles. The installers also use fancy drills for the double-brick walls to get the pipes+cables in. The modern flaring tools seem to run eccentric I noticed and they use electronic leak detectors, we used the flame+copper shield instrument and watched the colour change for a leak. An installation seems to cost as much as the unit itself, so it is great if you can do it yourself. I'd hate to see how much an installation in the bush would cost. The modern inverters seem to use PWM to keep the temp. and the compressor keeps running. Taxation as a means of achieving prosperity is like a man standing inside a bucket trying to lift himself up. Winston Churchill |
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| brianb Newbie Joined: 10/12/2015 Location: AustraliaPosts: 1 |
Hi Gizmo With the aircon are you running 12volt or 24volt ? I have 4x300 watt 12 volt panels 12 x Trojan t105 220ah wired for 12V 6000 Watt inverter Tristar 45 and 60 charge controllers Heavy duty cables Akai 2.7 reverse cycle aircon What I find is that it runs way to hot using the 12 volt setup so will be changing to 24v Off grid living in Lightning Ridge way to fun |
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| Gizmo Admin Group Joined: 05/06/2004 Location: AustraliaPosts: 5078 |
Hi Brianb By running hot I guess you mean the battery cables and/or inverter? Mine is a 48v system. As you scale up the 48 volt battery bank is the best option. Inverters can be a little more expensive for 48v, but there are much lower losses in the battery connecting cables, and less heat. Basically, the battery cables for a 48v system are 1/4 the size of a 12v system. I run 35mm2 wire for my battery, and it wont even get warm when I have the air-conditioning running. My air conditioned room is also insulated, which helps. I close it up and pull the curtains on the window, gets nice and cool very quickly, and I guess the air conditioned compressor is running at about 33% duty cycle. Glenn The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
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oztules Guru Joined: 26/07/2007 Location: AustraliaPosts: 1686 |
I have used the Downwind installation method for the last 10 years on 5 installs now.. including the latest on a small island out in the ocean ( about 120 hectares .. big green island) The last one was a Kogan for 500 dollars delivered to this island, and installed on Big Green. Max power seems to be about 600 watts... obviously the oz inverter does not notice it either.. I also installed one in a meat trailer... for hanging beasts. By fiddling the temp probes, it runs all the way down past -8C ( by mistake) it now runs @ 2C . It is inverter type, and can be run by inverter or inverter generator or 240v... neat system for a cool room. Glen.... mild climate is here in the ocean... wind is free too... ..............oztules Village idiot...or... just another hack out of his depth |
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