Gas Ducted Heating to Inverter Split System - Worth It?

• 

  jjjaar on 22/06/2025 - 16:43

  +5

  Multi splits can be pretty annoying. The inverter has to cover all of them, so will reduce output for each head. This means in winter they’ll often be a couple of degrees colder than you set them and hotter in summer. Not always, but often enough that you’ll notice.

  Splits in general though, definitely much cheaper to run than gas heating.

  • 

    mskeggs on 22/06/2025 - 17:48

    +7

    I would prefer several smaller units, than a big multi-head or ducted system too. Also likely that when time to replace them comes, they don’t all fail at the same time.

    • 

      jjjaar on 22/06/2025 - 19:48

      +3

      Exactly. Or, as my installers said they see often, an internal unit will break and the new models are no longer compatible with the external unit.

    • 

      noz on 22/06/2025 - 21:22

      +3

      The issue with several split units is the footpath around your house having multiple outdoor a/c heat pump units littered around.

• 

  mskeggs on 22/06/2025 - 17:45

  +1

  I have gas central heating and two split air cons in different rooms.
  I find the RC aircon units produce enough heat most of the time, so that is what I use to heat mostly.
  If there is some reason to heat the whole house on a particular day I can turn on the gas heater.
  I haven’t done the calculation for years, but then the aircon cost about half what the gas cost per unit of energy.
  Maybe see how your existing aircon goes before a costly upgrade.

• 

  JIMB0 on 22/06/2025 - 18:02

  +2

  What split systems have you currently got? If they're reverse cycle and inverter driven I'd be using them instead of the ducted gas heater, it's almost certain they will be cheaper to run. I insulated and draft sealed our house, we heat 3 of the bedrooms, 2 living areas and 2 bathrooms with a small 5kW system. The rest of the house we don't use and keep closed off. The unit runs 24/7 and only really struggles on the coldest mornings.

  It's cheaper to have the split system running 24/7 than it was to use to use the ancient gas ducted heater for 5 hours at night and an hour in the morning. The pilot light alone cost $40 in gas every 2 months. The heating ducts themselves were a big source of drafts and sealing them off made the house noticeably warmer.

• 

  SupeNintendoChalmers on 22/06/2025 - 18:03

  The rep mentioned that the current maximum rebates end this financial year, with future rebates shifting focus to solar panels and batteries.

  Bare in mind through that usually once you use one of these rebates, you cannot claim another one.

  Every state is different, so YMMV

  This is Victorian eligibility btw

  https://www.solar.vic.gov.au/hot-water-rebate#check-if-you-a…

  As a Victorian householder, you could receive a hot water rebate if:

  ….

  the property address has not already received a hot water or a solar battery rebate under the Solar Homes Program

• 

  Serpentis on 22/06/2025 - 19:04

  +6

  Eh, I had a multi split system installed recently. It does the job, but the "inverter" part doesn't really do much when multiple heads need different heating, it just runs the compressor high and cycles the heads on and off to maintain temps. And the minimum output isn't as low as what a single split can do, so when it gets near the set temperature it'll cycle. And with an 18kw multi split, that'll cycle like crazy. You'd think it would be good synergy to have one compressor for multiple indoor units, but it's the opposite, all the indoor units want different heating and the compressor can only do one output at a time so nobody is happy. The result is more temperature fluctuations compared to other setups. Fortunately I've got good insulation so these temperature fluctuations aren't too bad, but if your insulation is no good then you'll feel it.

  If you already have two single splits just install single splits on the other rooms. They'll run smoother, more efficiently, and easier to replace since you can just upgrade one by one. And if you don't have good ceiling insulation, get some, it helps a lot. My multi split is fine, but in future I'm going for single splits. The upside of having only one outdoor unit is just not worth all the multi split operational downsides (unless you have no choice).

  • 

    JIMB0 on 22/06/2025 - 20:21

    Cycling on and off is really bad for efficiency. It takes a certain amount of energy to establish the refrigeration cycle, this is then lost everytime the system stops. It's one of the reasons they introduced inverter driven systems.

    • 

      Serpentis on 23/06/2025 - 00:16

      When I say cycling that includes just an indoor unit valve opening/closing when the compressor is already running, it's just juggling refrigerant around. The whole compressor cycles maybe 2 times an hour (when set temps are reached). The efficiency is pretty good, well within expectations. I'm sure single splits would be better, but this isn't far off.

• 

  bigdog989 on 22/06/2025 - 20:45

  +2

  My parents have a ducted reverse cycle system (I know this is a little different but there are some similarities). It has failed a couple of time which does highlight the issues with single unit systems. If it fails you lose heating and cooling across your house, and given it’s a pretty big single system it’s very expensive to repair/replace.

  I would suggest multiple individual units. I know it might cost more up front and means having more outdoor units but it will save you in the long run….

  • 

    kiitos on 23/06/2025 - 09:29

    It depends on the floorplan of the house too as to how practical multiple splits would be

• 

  Brucet on 22/06/2025 - 22:00

  +2

  No, I keep my Gas Ducted Heating and paid $ 1700 for a new Inverter Split System.

• 

  Joey2scoops on 23/06/2025 - 07:48

  The better end of heat pump hot water systems are in the $4-5k range.

• 

  jjjaar on 23/06/2025 - 07:54

  +4

  The rep mentioned that the current maximum rebates end this financial year, with future rebates shifting focus to solar panels and batteries.

  I just realised that we’re still in June. Of course they’ve said this, they want you to lock in before June 30. Any company that can sort this out in a week is a concern. Decent companies have lots of clients and can’t just add another one in within that period of time. Let alone the fact that they clearly just have the products lying around.

  FWIW when we got our splits a year ago, it was a few weeks wait minimum for the trusted installers to find a time in and around their other clients, and they had to order the stock in that we’d specifically requested.

  There’s no change I can see for the rebate of removing your gas ducted.

  And rebate for hot water is changing, but not getting worse:

  From 1 July, households that choose an eligible hot water system made in Australia will receive a higher rebate of $1,400. The $1,000 rebate is still available for customers that choose to install other hot water systems.

  https://www.solar.vic.gov.au/driving-down-power-bills-and-su…

• 

  rexanator619 on 23/06/2025 - 10:20

  +1

  Hearing about the "Silent killer" made us cease operation of our ducted heating system. That is the risk of carbon monoxide poisoning.
  The chances are lower with proper maintenance, although we preferred to switch for peace of mind. Changed to reverse cycle split system units.

  It's been a number of years and we have saved a substantial amount in gas bills as a result. We've got solar panels, so electricity bills have not skyrocketed.

• 

  netjock on 23/06/2025 - 12:12

  The rep mentioned that the current maximum rebates end this financial year, with future rebates shifting focus to solar panels and batteries.

  This is just a tactic.

  If you think about it. You put in solar and batteries and continue to have to burn gas. They want to get people off gas. How do you get people off gas, replace gas appliances.

  My gas bill for September - October 2024 worked out to be $650 from using ducted heating, gas cooktop and a 30 year old gas hot water heating system.

  A good $60 is supply charge. Then you need to check the baseline cost for your cooking and hot water which could be another $60 for two months. So that is $120 for 2 months. You really have to measure the cost across winter rather than two of maybe the coldest months.

  Also need to consider whether you go to instant gas for hot water because when you heat pump goes you're up for $2k replacement depending on expected life.

• 

  Rahonui on 23/06/2025 - 20:05

  +1

  I'd replace the hot water system with a heat pump. You'll get govt rebates, and will notice more of a difference in the gas bill for less outlay

• 

  McSquintus on 25/06/2025 - 17:06

  I'm looking to get my gas ducted heating replaced myself. Leaning towards a reverse cycle ducted system with zoning as I don't want multiple units on the walls and boxes outside. I am just not sure if my electric bill will be high as a result. I also don't have any aircon in the house so need something by summer.