Browse Forums Heating, Cooling & Insulation 1 Nov 06, 2009 8:00 am Hi Everyone, I am in the middle of researching the differences between purchasing a 1 or 3 phase powered ducted split system air-con. On face value, it appears that the 3 phase is much cheaper to run. Does anyone have any further information, or experience with a 3 phase unit? Ray Re: Single or Three Phase Power for Air Con 2Nov 06, 2009 10:32 pm The best way to reduce your A/C running costs is to reduce the heat load on the house. Our house has been designed to reduce the sun's intensity during summer. Outside can be 33 and inside only 25. see Passive Cooling Re: Single or Three Phase Power for Air Con 5Dec 30, 2009 10:25 am Three phase is definitly not cheaper to run (silly misconception), it depends on the unit and its energy efficiency. Three phase ducted aircons are normally required for larger homes (30sq+), also depending on how many zones you want to have. Three phase power is required to power very large motors (industrial grade basically). Doesn't matter now anyway as you can buy a single to three phase converter if you home wasn't fitted with three phase originally. Saying three phase ducted is cheaper to run is just like saying running a V8 car is cheaper than an 4cyl or a 6cyl (as the V8 produces more power and torque in the same amount of time). True BUT it naturally uses more fuel (read power in air con systems) to product this extra power. Al & Caitie- Building the Hamilton 278 (Coral) at Narangba Re: Single or Three Phase Power for Air Con 6Dec 31, 2009 9:05 am mauricito Hi Everyone, I am in the middle of researching the differences between purchasing a 1 or 3 phase powered ducted split system air-con. On face value, it appears that the 3 phase is much cheaper to run. Does anyone have any further information, or experience with a 3 phase unit? Ray I did a similar exercise and went with the 3-phase option but not only because of efficiency considerations. Our house is 335m2 and we want to cool 190 of it, for that size the Daikin installer recommended a 1-phase 15.5kW unit but only if we don't have all zones open at once. The Actron installer suggested a 19kW 3-phase unit "don't go half-backed", I don't fancy a fight with my kids over open zones - I went with the Actron option. It cost $450 to get the meter box rewired to 3-phase, it was all very easy and painless as we already had 3-phases going into the box. As for efficiency, the Daikin 15.5kW ECC is about 2.6, they also have that model available as a 3-phase unit which has about the same ECC. The Actron 19kW has an ECC of about 3.3 so it is more efficient. For about the same input power we get 19 instead of 15.5 kW. Better still, the Actron ESP Plus can run the outdoor unit between 10 to 100% of capacity because it uses a digital scroll compressor, whereas inverter based machines generally can't go below 40%. The ESP Plus also has a variable speed indoor unit so again it scales back when maximum power is not required. I'm a big Daikin fan, we have one at work and it's brilliant, I have a Daikin 3.5k split in my home office which I also love but their larger 3-phase units are about 800mm deep which meant I could't fit one into my yard nicely, that was the big decider. At any rate the Actron ESP Plus is also great and more efficient in so many ways, 5 star rating. How many m2 are you cooling? Do you have any brands in mind? Hope that helps. Re: Single or Three Phase Power for Air Con 7Dec 31, 2009 9:19 am dymonite69 The best way to reduce your A/C running costs is to reduce the heat load on the house. Our house has been designed to reduce the sun's intensity during summer. Outside can be 33 and inside only 25. see Passive Cooling I'm a fan of passive cooling too and have already spent a considerable amount of time and money ensuring we need no or minimal air-conditioning. I was most impressed when it was 44 degrees outside and only 25 inside, 26 upstairs, there was a slight breeze but it made all the difference. Last November, however, there was next to no breeze and our house got overpowered by that heat, then all that wonderful insulation just made sure we stayed hot all night. Kids couldn't function at school, I was a zombie at work. We installed air-con after all but I figure it'll only get used "in case of emergency", those 33 degree days are no problem for us. In future, when I can afford it, I want to improve our passive cooling, the roof cavity seems to roast, whirlybirds or attic fan? The North facing windows also let a lot of heat in, awnings and or tint? Do you have any ideas about the roof and windows? Cheers Re: Single or Three Phase Power for Air Con 8Jan 01, 2010 11:48 am A.Ryder dymonite69 In future, when I can afford it, I want to improve our passive cooling, the roof cavity seems to roast, whirlybirds or attic fan? The North facing windows also let a lot of heat in, awnings and or tint? Do you have any ideas about the roof and windows? Cheers As long as the roof space heat isn't being transferred to the rooms below it shouldn't be too much of a problem. Roof space ventilators will help but may not remove all the heat generated on higher temperature days. We're planning on using removable external shading (awnings, decidous trees and roller shutters) for our North and West facing windows. Hopefully this will allow us to stop heat infilltration on hot days but let the sun in during cooler periods to help warm the house. Re: Single or Three Phase Power for Air Con 9Jan 01, 2010 12:55 pm So what do you do when the air con company says normal power is all that is needed for the unit being installed but the builder insists on installing 3 phase for the air con system?? Cheers Kim Re: Single or Three Phase Power for Air Con 10Jan 03, 2010 10:17 am Yeah, Coral have a habit of pushing big three phase units even though they are not required (they are making more margin $$$ on more expensive systems). We built the a slightly bigger Hamilton 278 and they gave pushed a three phase ducted system even though a single phase system would have been more than adequate. We ended up getting a 2.5kw (master bedroom) and 3.5kw split (Activity room) for the mean time. We will be getitng a 5 or 6.3kw split put in the kitchen/family room most likely too which will mean the whole house can be cooled by aircon quite cheap. 2.5kw = $744 (unit) + $550 (air con installation) + $180 (power point installed in roof and wired back to meter box on its own circuit) = $1474 3.5 = $962 + $550 + $160 = $1673 6.3kw = $1610 + $550 + $180 = $2340 = $5487 Whole house air conditioned for $5487 vs $14 000+ (+ cost of three phase power) as recommended by Coral. Our planned set up will be much more energy efficient too (Mitsu Heavy Industries with 5 start cooling efficiency). Ducted is a waste of money in single story homes in my opinion. Al & Caitie- Building the Hamilton 278 (Coral) at Narangba Re: Single or Three Phase Power for Air Con 11Jan 03, 2010 3:10 pm alk Yeah, Coral have a habit of pushing big three phase units even though they are not required (they are making more margin $$$ on more expensive systems). Whole house air conditioned for $5487 vs $14 000+ (+ cost of three phase power) as recommended by Coral. Our planned set up will be much more energy efficient too (Mitsu Heavy Industries with 5 start cooling efficiency). Ducted is a waste of money in single story homes in my opinion. Seems silly doesnt it - especially when we are doing the air con out of contract! They still insist on 3 phase for some reason??? We habe been thinking too maybe we are better off with a few split systems - biggest problem is our big open area....but will post plan & thoughts on my thread later - sorry op..back to you. Cheers Kim How do you remove one of these ceiling air con vents? And is it possible to disconnect the duct joined to the vent from inside the house, without going into the roof cavity? 0 5936 Hi all, sorting out the ducted air con for a 350sqm double story house. Does this placement sound reasonable to you? Also, I plan to have 6 zones I think. Living room… 0 0 Hi all, sorting out the ducted air con for a 350sqm double story house. I think i plan to have 6 zones I think. Living room (mainly for entertainment so not used often),… 0 0 |