Thread: 3 phase split system

how is a 3 phase cheaper?

Tom,

I've recently put in three phase aircon at work, although I have no idea what H.P. the unit is and care even less I can tell you it cost $3,500 to install the 3 phase power and that was even with the lines allready run to the verandah. By the time you upgrade the power box, pay the TXU truck etc etc it really adds up.

As pulse asked, how is it cheaper, you have to have a really large house to need anything larger than 3.h.p.


John.

Thanks guys,

the thing is I already have 3 phase at home, had it put on 3 years ago for my welder, cost me around $1000 all told to get the service on including rewiring of my existing panel to split the house across the phases.

The units I have been looking at are around 5Kw of cooling for our main living area.

So lets look at a few energy usage tables

As an example a single phase 6.7kW air con - it runs at 13.2A at full noise
Now another example is a 3 phase unit that runs 15kW

Now that runs 8.1A across the phases which equals 24A however from what I have read and due to the separation of the phases, when you power 3 phase devices you essentially are billed for 2/3 of the power usage i.e. it would only be costing you 16A to achieve 15Kw.

I am just trying to clarify the last part there, I am having trouble doing that - spoke to a few sparkys that have given me that info but I need to see it written down .... working on that now

That aside even if you are powering an AC unit that was using 10A on a single phase circuit or 3.33A on 3 phase circuit for exactly the same kW output you would use less energy powering the 3 phase unit as there is less loss in providing smaller amounts of current 3 times - your delivery efficiency is increase.

More research to be done yet .... just thinking out loud

Tom