Hi,
I am wondering anyone has installed multi heads aircontioners before?
We are thinking to have 2 -3 rooms with one outdoor unit.
is any downside of doing this? hope it still work as well as normal split system
installation are they expensive?
Thank you for any reply
Yes you can have exactly that and I reckon they are great, I have an 8kw Fujitsu for my 4 bedrooms and another completely separate split system for the lounge room. I wanted to A/C my townhouse but couldn't have heaps of units out the back (body corporate would not agree) and my ceiling/floor is not large enough to run ducting for central A/C.
They work just as well as a split system. You just need to make sure the internal heads don't exceed the output of the compressor otherwise they won't work at their full capacity if all turned on at the same time.
e.g You can get 3x 4kw heads if you need to, but you will only be able to run two at once to their full capacity (4kw+4kw = 8kw) or all three at 2/3 their capacity (4kw+4kw+4kw x .67 = 8kw), so you just have to watch out for that because if your head units are only just big enough to cool/heat the area and you run all of them at once, none of them will cool/heat the area properly and you will think the whole system doesn't work. Most bedrooms only really need a 2kw or so head anyway so you should be okay.
Your longest run (distance from the outdoor compressor to the internal head) is best kept to 15m maximum (off the top of my head, but maybe it is 12m). I have two heads at the max distance and they work fine, any furher than that and it is more stressful on the compressor motor I believe and they probably won't work properly. You also need to have somewhere to drain from the head unit so it can get rid of the water it creates.
Each head unit only pulls as much power as it requires, so they are pretty efficient too (or that is what I was told). Yes they will cost more than a single system because you are effectively gettting 2,3 or 4 split systems but they are obviously cheaper than 3 or 4 separate split systems. They are also more expensive to install than a single system but once again not as expensive as three separate system installs. Sometimes it is more economical put in a ducted system for the whole house though. Worth asking the question to a local AC installer. Mine was a realatively cheap install too because it was through a friend. If you need to know roughly what size you need to cool each room you can use this calculator http://airmerchants.com/whatsize.html (my friend) and then you can work out roughly how big a multi head you would need as well.
For my circumstances, I found it was cheaper than installing spearate split systems and it kept body corporate happy as well. Win-Win for me, but of course your circumstances may be different.
Good Luck.