Thread: Ducted whole house or wall splits ?

Daikin 4MXS80 outdoor can run 4heads 3x 2.5kw and 1 x 3.5kw
or
Daikin RXYMQ5AV4A 14kw to 4 heads 7.1kw 3.5kw 3.5kw and 2.5kw

Above is possibly going into my new home and quoted installed at $9200.00 for the first and $13900.00 for the bigger unit

Getting three more quotes still

The other thing I've noticed is a drift towards R32 gas, replacing R410 which is a mixture of two (?) gasses, one of which is R32
Propane is, AFAIK, 'the' most efficient gas, but Fear of ("inevitable") FIRE seems to restrict it's use...

I'm trying to avoid putting units up into the roof void, as the structure of our roof (pine pre-built trusses and zincalume) seems prone to low frequency resonances...which is an Absolute Pain as well as being - literally - nauseating. - I'm now wearing my BOSE QC-25 Noise Cancelling headphones around the house. Kills the low frequencies 101%, but sadly, passes most of the .... Voice Frequencies...

SWMBO is talking about replacing the current evap. Breezeair with the latest 'stepper-motor' driven one, reasoning being that the vibration/fault seems to be in the motor (conventional induction type) or it's speed controller... a gust of high wind causes the fan to speed up...and stay 'up' there, vibrating the roof-beams...
The only advantage I can see for retaining/replacing the evap 'box' is better efficiency of the fancy motor on low speeds for overnight cooling, around 80~90 watts. - they claim "60 watts..."
Seems that late Jan to early March is the 'humid' season nowadays.

But as our Family room is 80 square metres, and is the main one we'd like heated in winter.. I can still see a 6 to 8kW reverse-cycle split in our future. (7 to 9 on heating...)
The idea of one pump running several wall-units is interesting...

Daikin is looking like the top of the short list.... followed by Mitubishi Heavy Industries.

Edit:- Looked up the Breezeair running comparison chart - http://www.breezair.com.au/why-evapo...-running-costs and to be realistic, 'only' $200 extra gives the advantage of a heating unit in winter. Should be able to halve that by adding another 1kW of PV panels on the roof...

Fujitsu were the first to start rolling out R32 something like two years ago ?
At the time there were no wholesale supplies in Oz.....

Can't recall the pressures it runs on, but R410a runs very high pressures.
They are almost getting up at hydraulic type pressures.
I've seen 600psi on the high side during heating.

it's an uncomfortable feeling to know that your flimsy looking gauge set and hoses is holding that sort of pressure and that a hose failure will more than likely take you out......

Originally Posted by superquag

I'm trying to avoid putting units up into the roof void, as the structure of our roof (pine pre-built trusses and zincalume) seems prone to low frequency resonances...which is an Absolute Pain as well as being - literally - nauseating. -

Modern ducted fan coils are very good in terms of noise, and can be resiliently mounted to reduce any further noise transference, although not too many domestic installers would do that.

Originally Posted by rick130

IIRC you can get up to four heads on one outdoor unit, (depending on brand) any multiple of head capacities up to and slightly exceeding the outdoor units rated capacity on a domestic split.

Large commercial VRF/VRV (variable refrigerant flow/variable refrigerant volume) systems can use a huge number of heads on a single outdoor unit.

It's incredible where air conditioning is these days.

These types are very efficient,but there are issues.We service some of these systems and they have over 15 indoors to one outdoor.

Refrigerant leaks are often extremely difficult to locate,as pipework is usually concealed in walls,etc.
If there is a problem with the outdoor,the complete system is down.
The systems are very complicated and difficult to sort if there are problems,although most manufacturers these days have pretty good tech support.

I know of a couple of these systems that were replaced at massive cost as parts were no longer available for the outdoor unit,therefore it could not be repaired,and one was a Daikin,less than 10yrs old.
All the pipework needs replacing,not just the units.

That said,Daikin do have outdoor units running on R410 that can be fitted to a R22 system in some cases.These new condensing units are amazing,they flush the old mineral oil out,and don't let pressures exceed the rating of the older pipework,etc.Very handy in coastal areas where the outdoors rust out well before the indoor units.

Wall splits are way more efficient than ducted units,and there is the ability to use only the unit in the area you want.
But the outdoors and indoors may not suit the residence,particularly the outdoors, making the residence look like a motel.

Inverter ducted units single phase seem to have a lot less electronics in them than three phase units,but i don't know which one is the more efficient.You would have to look at the manufacturers ratings closely to work it out.

Brand wise we usually use Mitsubishi Electric(not Heavy).Since using this brand we have not had ONE warranty repair,in close to 5yrs.
They have been a bit late going to R32,although the new models using R32 are now available.R32 runs at slightly higher pressures than R410a,but has around 30% of the global warming of r410a,and units running R32 are more efficient than units running R410a.It is slightly flammable,and is only used in wall splits at the moment.There is actually a chart to follow to make sure a room is not to small compared with the quantity of refrigerant in the system.

Daikin are by far the most efficient,but you will have to pay more for the most efficient models in the wall split range.
We do more repairs on Daikin units than any other brand,but that could be because there are more around,very hard to quantify.We have also had a few Daikin repairs while under warranty over the years.

Slightly off topic,Mitsubish Electric back their products well,and will also provide 12 months warranty in a situation where a unit is not used for comfort cooling such as a server room.Daikin give you no warranty at all,nothing,zilch.We once found this out the hard way

As Rick said,MHI are not to bad either,we have used a few and had no issues.

Agree as well,the way AC is evolving,is amazing.

Originally Posted by rick130

Modern ducted fan coils are very good in terms of noise, and can be resiliently mounted to reduce any further noise transference, although not too many domestic installers would do that.

The problem is there are not too many installers that actually know what they are doing.

Most just want to throw it in,get paid, and race off as quickly as they can,hoping the customer doesn't ring again.The majority of them are not fully qualified,and have no idea how a system operates.

Using a good installer is paramount.

Originally Posted by scarry

Slightly off topic,Mitsubish Electric back their products well,and will also provide 12 months warranty in a situation where a unit is not used for comfort cooling such as a server room.Daikin give you no warranty at all,nothing,zilch.We once found this out the hard way

As Rick said,MHI are not to bad either,we have used a few and had no issues.

Hi Paul, I was working on a Fujitsu VRF job in Sydney for three weeks in September.
Roughly thirty three heads per floor, mainly bulkhead units but several ducteds per floor for common areas, four floors, three pipe system.
We were using digital gauges, noting temps and pressure testing for up to a week to ensure no leaks !

That's interesting re Daikin and non comfort cooling !

MHI used to give a five year commercial warranty and pretty sure it was the same for non comfort cooling as I've used them in telephone exchanges for the NBN. (should check my paper work, I'm still a warranty service agent. )

MHI and Daikin were specced anyway, so that's what I used.

Originally Posted by rick130

Hi Paul, I was working on a Fujitsu VRF job in Sydney for three weeks in September.
Roughly thirty three heads per floor, mainly bulkhead units but several ducteds per floor for common areas, four floors, three pipe system.
We were using digital gauges, noting temps and pressure testing for up to a week to ensure no leaks !

That's interesting re Daikin and non comfort cooling !

MHI used to give a five year commercial warranty and pretty sure it was the same for non comfort cooling as I've used them in telephone exchanges for the NBN.

MHI and Daikin were specced anyway, so that's what I used.

The Fujitsu job would be a worry,i wonder how it will be going in 10yrs time?
Architects,consultant engineers love them,but in the long run?

Just trying to work out if the system is short of refrigerant is a major job.

Maybe i am too old school,don't mind refrigeration,it is generally nice and simple.And there don't seem to be many real fridgies around,just lots of fan mechanics

Saying that,some of the young guys are pretty good at the electronics,even my own boys that grew up doing refrigeration are very good at fault finding the electronics on these new AC systems.They have probably changed around 30 PCB's in the last month and didn't have an issue with one,touch wood

That Daikin warranty issue is not well known,we haven't been the only ones to get caught out.
Also many of the Daikin ducted indoor units,around the 18 to 30 KW sizes are impossible to service on some jobs.Side panels don't come off the units,only way in is take off the top panel,impossible if it is jammed up against the roof

Just cleaned out my shed,moving to a bigger one,found 40kg of virgin R12.
Not much use today.

Just thinking,what pressure did you use to pressure test the pipework on the Fujitsu system,i presume it was 410a?