Did you get any independent feedback from a third party?
Assume the 18 kW is the rated heating output of the unit recently installed? (Approx 5kW electrical load)
The suggested upgrade of a further 10kW heating output will add approx 2.8kW of electrical load based on the Daikin range. The total installed electrical load will be 7.8kW. Whether you will require a 3 phase power upgrade will depend on the local supply authority rules and existing home needs.
Daikin lists 18kW models available in single or 3 phase. It’s important to consider the impact of converting to 3 phase as it will impact the relative benefits of your PV system. Best to ask the supplier of the PV system and supply authority how that might change? Have you asked your Ducted System supplier to explain how/why you need a 3 phase upgrade?
Are you including the ability to zone control different areas within the home? This will reduce the energy consumed. The inverter type heat pumps adjust the power they use to match the heat output required for comfort. Your supplier should be able to offer advice on the best strategy for minimising power consumption.
By splitting into 2 units 3 phase is not required. I suspect this is why they installed 18kw when really it needed 20kw. We’ve struggled to get the system running for 2 years - we’re heading into our third winter - so this feels like a win!
We have zoning already.
No we didn’t end up having a third party look at the system, but we do have time to do that.
I wasn’t sure if we should ask them to take out the 18kw unit and replace with a 10kw, but from what you are saying it will heat as required, not use the whole 18kw.
While it might be close to done and dusted it would serve you well to get a second opinion. There are many nuanced issues that are difficult to convey although @mark_m did a fine job highlighting many.
Sometimes a 10 and an 8 (for example) will provide a better outcome than one 18. How many speeds does the blower have? If the lowest speed is fairly high the comfort level will be different than a small unit with smaller/slower blower, hoping that makes a point. Comfort levels are individual to each of us and subject to many considerations.
If I had to do my 9.5kw split again knowing what I know now, I would have installed two smaller ones and probably run them both together and achieved a better comfort level in the area. The point is experience is less valuable after the fact but a second and even third opinion on capacity, airflow, and comfort issues would not be time poorly spent, even if it reinforces your pending solution.
Off the top of my head I would expect upgrading your house connection (ignoring the cost of internal wiring) to 3 phase wiring would be so horridly expensive to rule it out from the start.+++
The problem is not that domestic single phase wiring cannot supply enough power to the house as a whole. The limit is what can be supplied on each circuit from the board as there is a maximum weight of wire (and hence current capacity) that can be used on each circuit.
As already mentioned having more than one compressor gets over this problem as each will have its own circuit.
Another possibility, that I have seen with a stove, is having more than one circuit per device. I have no idea is this is available for AC. As others have said two systems may be more efficient anyway.
+++ When building my house the poles and wires authority of the day and I were talking about size of transformers, connection dates etc and the representative asked if I wanted to run any heavy equipment as then I would want 3 phase. Some people have sawmills, huge chicken sheds etc that can use much power. I said no single phase would be fine and in any case the 10KV line that went by was only two wires. He grinned and said ‘oops’.
Good points Phil and thanks. That’s often the problem that you have the experience but can’t go back and change things. We have that option now and need to make the right decision.
All of the replies’, you have to be put your minds to accept such results from a world wide renowned company.
You are being jerked around, how do the American’s living in the high mountains live without aircon. or the Europeans winter without aircon.
THERE, the companies get it right.
DONT take any BS about heat pumps, heat exchangers and all that bs.
the system either works as intended or it was substituted for an interior system not designed for the job intended.
contact consumer affairs in your state, hire an advocate and go for them.
Installer and and all.
In the end you will find that the installer substituted a cheaper and inferior system, charging full price for Crap that don’t work.
Friend, take heart and GO FOR IT.
the only thing you have to loose is virtually NOTHING.
In all states of Australia all consumer complaints are deled free!
I hade a claim against a builder, went to consumer affairs had judgement against the builder and won.
DO IT!!!, YOU WILL WIN!!!
Thanks for your comments Fred. Totally been jerked around but at the end of the day we need to be warm. We live in Tassie and winter is coming, so had they not come to the party I would have been “going for them”. I’ve made their life hell for two winters already and the threat of a bad google or FB review is always of concern these days. It’s the biggest weapon we have actually!
I am confident this outcome - which they have suggested and offered - will work.
I have my own business, I work more than full time and there is only so much time you want to spend on this sort of stuff when they have been “trying” to sort things out the whole time. They’ve actually done a lot to try and resolve without - I suspect - admitting they had got it wrong. Can’t fault the customer service at all, although we do have a big problem in the NW of Tasmania with whitewashing I’ve found.
So again, thanks everyone and I’ll bear this in mind for future problems. Onwards and upwards.
Not sure if this will work for you. Our split system (Mitsubishi) couldn’t heat (showed a fault condition) on a few really cold mornings in Melbourne. We got the serviceman around to make sure it didn’t have a problem - he checked the compressor and all the pressures and tested it and couldn’t find a fault. So the next time it showed the fault condition we turned it onto cool inside for some minutes, then back to heat inside and it worked perfectly until the next time it was very cold outside. By turning it onto cool inside we think it was heating the outside unit enough to get it going (sort of like putting a heat booster on it).
If the outside unit was frosting it would essentially shut down; turning it onto cooling would cause the outside unit to warm, eg defrost. I would think any unit installed around Melbourne would be suited to minimally withstand mild frost (or frost inducing temperatures). It sounds like your problem is when the temperature/humidity are on the edge and any anti-frost doesn’t kick in as it should, assuming you have one. It could also be a fault with that functional unit in the system.
It could be, but the Self Diagnosis function (via Run light flashing in lots of 2 as listed in the User Manual) was telling us Compressor blockage which is why we, got it checked out initially, then turned the unit to cool from heat (to see if we could “unblock” the compressor, we figured we had nothing to lose. It worked every time.
Not necessarily. In this case showing that the goods supplied are not fit for purpose is not straightforward. Mounting such a case will not be cost free - at least in time and effort. The OP says they need a solution soon as winter is coming on.
Hey Mel, I live in the East Tamar in Tassie and I have been fortunate that my Daikin units have been fantastic since installing them about 4 years ago. I did have to make sure though that windows are double glazed, external doors are fully sealed, window coverings on all windows, insulation in walls, ceiling and floors and the outside units are protected from frost. I also chose to replace (very worn) floorboards with carpet and tiles. Mine were purchased and installed by Degree C who have been wonderful. I do hope the problem is fixed soon - it is already electric blanket at night weather here!
As they are likely inverter units they will step down the power requirements based on load. It will mostly use 18 kW until it steps down to ‘normal operating’ conditions when it may use far less than the 10kWs they discuss.
Is it a problem going to 3 phase, if it is required? While we are in Qld and so no way to compare coatings, we chose to go 3 phase so 1. We could maximise our output to the grid and 2. So we could install a battery which regulations required we had 15kW of line capacity (10kW from panels and 5 kW of battery inverter).
5kW is considered as an upper limit for single phase solar output and anything over that requires more phases eg between 5 to 10 kW at least 2 phase required and above 10 to 15 kW 3 phase. I assume without certainty that this would be a similar input draw across phases. 3 phase requires new metering, some small changes to the wiring in the board and 2 more phases of cabling to the box (usually done as a 3 phase cable and disconnect of the old single phase). So at the estimated 7.8 kW @mark_m advised, 2 phase at least may still be a requirement to safely draw from the grid. Something worth asking your energy supplier before proceeding.
Our 20 year old 14 kw Daikin doesn’t work very well either when the temperature is just above freezing in Northern Tasmania but I believe this due to most mornings being foggy and extracting heat from moist cold air very quickly causes the unit to ice up.
I don’t really see how this problem can be avoided.
We now leave our unit running 24/7 in winter but turn the thermostat down to its minimum (16 deg) overnight.
I’m considering replacing the unit due to age and hence am interested if there is anything better.
What might be most suitable for your part of Tassie and cost effective, there are alternatives. Hopefully your nearest professionals are equally familiar with the problem, and have practical recommendations for a replacement.
A ground source heat pump is the most expensive to install, assuming your site is suitable. Gold stars for performance and running cost.
A current technology inverter based replacement air sourced heat pump, properly specified for your site conditions may offer the best value. The professional system designers are capable of advising what level of performance or loss different replacement product options will provide. My reading of the performance of some sample systems under high moisture low temperature conditions. Heat output can be reduced by more than 50%.
The only real solution is a ground source heat pump, but even though we have the room to install one, I suspect the cost would be prohibitive. I don’t think the systems are common in Australia so it would probably be a custom build (Expensive), and the ground source installation wouldn’t be cheap.
The problem really only becomes critical when operating with air temperatures just above freezing with high humidity, something that’s very common where we live.
A new heat pump would probably be a big improvement.
We do also have a wood heater but that takes a reasonable time to get up to heat.
The house is 70 + years old which doesn’t help.
The only other solution that does work is to run it 24/7
A bit of a dumb thought but would setting it to de-humidify overnight work better? It would cycle between hot and cold but that should de-ice the outside coils regularly and keep the inside reasonable (possibly)??
Your old split system had two advantages over your ducted system:
It didn’t lose heat through the duct walls;
It didn’t need extra fan power to push warm air through the ducts.
Also, air to air heat pumps are least efficient between about zero and 4 degrees, because they ice up. They don’t ice up so much below zero, because below zero the air is drier.
Having said that, it seems that your new system is under-sized for its task.
P.S. I did my 1980 U. Tas. masters project on The Feasibility of Heat Pumps for Domestic Heating in Tasmania, and I am currently on my fourth heat pump.
