Air Conditioner as Heater for Winter

JohnnyB.Cheap on 09/05/2023 - 08:27

With this recent cold snap the $20 kmart heater from 10 years ago has come out again and is looking to cost us $300 this winter. My partner has floated the idea of instead of $300 spending on running the thing we spend ~$1700 (unit+installation+energy) to switch to a reverse split system. While not quite a saving, we are living quite modestly and with the El nino incoming it could be a good time to get Aircon in before the return of 45 degree summers. I also refuse to use fossil fuels to directly heat my home.

I am approaching this from a QoL perspective, rather than spending the least amount possible. That is to say, I'm happy to spend upfront to save long term.

Owners of Aircon units, I have some questions…

  1. Do you use it for heating over other devices, if not why not?
  2. Does anyone know the decrease of efficiency that having the outdoor unit in sunlight would cause in summer? Should it govern our installation location?
  3. There are general rules out there for what kW rating for what m^2 . For people that chose the bottom end of the range do you regret it or is it serviceable?
Electrical & Electronics Air Conditioner

Comments

  • Jimothy Wongingtons on 09/05/2023 - 08:32
    +34

    We find using the aircon to heat during winter is more comfortable than an actual heater. The heater makes the room way more stuffy quicker

    • McSquintus on 09/05/2023 - 08:41

      I have a very old top vent wall furnace and also a standard aircon. I definitely notice the wall furnace heater makes everything stuffy and wasn't sure of upgrading the aircon into one that could also do heating. I am more interested in doing so now but I heard the reverse split system will not be as effective in heating larger spaces. Or do I just multiple split systems in different rooms of the house…

      I'm torn on what heating solution to upgrade to without spending a fortune of installing ducted heating.

      • dasher86 on 09/05/2023 - 10:17
        +8

        I would go splits vs ducted any day anyway. You have more control of zones, and generally they are cheaper to run.

        • iamherenow on 09/05/2023 - 13:27
          +17

          If you want to heat/cool a whole house ducting is much better. No way I would put in 5+ split systems (3br, living, lounge), and then still have hot and cold areas when you travel in hallways and bathrooms and study.

          • Mokr on 09/05/2023 - 14:15
            +2

            @iamherenow: But it's way more cheaper to run that system.

          • dasher86 on 09/05/2023 - 14:33
            +10

            @iamherenow: This is where people differ in how they want things, and why I mentioned zoning.
            I have a 5+ split system on a two storey house.
            I only heat the individual rooms I need and it works for me.
            Why do I want to heat my 5th bedroom if no-one is using it?

            • iamherenow on 09/05/2023 - 14:43
              +1

              @dasher86: I agree. I use the whole house.

              It's also about insulation. I put in the heat at 7am, and then my cost to hold that temp for the rest of the day is very little. In my old house with poor insulation there is no way I would do ducted heating/cooling as half the house was so poorly insulated the heat would be gone in minutes and would cost a fortune.

            • ozbargainsam on 10/05/2023 - 18:13
              +8

              @dasher86: Ducted has zones, too, you know. I have 8 zones on my ducted house. Not to mention the other benefit is that you can focus the heating/cooling in one zone by switching the others off for a bit. I've even got individual % air flow to each room.

              You'd be used to it, but the bad aesthetic of having the wall units on most rooms - happy to pay the cost to have the integrated ducts.

              • h0mbre on 11/05/2023 - 18:06
                +1

                @ozbargainsam: 8 zones is very good and would be quite efficient.
                Unfortunately the overwhelming majority of houses have 2 maybe 3 zones maximum.

            • Archi on 16/05/2023 - 14:13

              @dasher86: because ducted heating and cooling also have zones.

        • McSquintus on 09/05/2023 - 20:26

          Thanks, never thought of it that way. This thread has helped.

          • WhyAmICommenting on 11/05/2023 - 10:42
            +2

            @McSquintus: Once your ducted breaks you’ve got nothing in any room.

            • ozbargainsam on 13/05/2023 - 20:17

              @WhyAmICommenting: Can't argue with this.

              But I'll be damned if I'm putting 8+ units inside the house and another 8 on the outside. I know 'aesthetic' is a premium but the compromise of the wall units making my rooms look like office' suites is not something I want.

        • Alpine58 on 12/05/2023 - 08:29

          100% agree with this.

          Put a ducted system, 6 zones (with customisable % settings) in a 3 bed house. Wish i did separate splits.

          Much more versatile, less open doors for return flow, and in Australian houses with poor air tightness your ducted ends up sucking a lot of cold air in if you dont get your pressure/flow balance right.

          • sriver on 12/05/2023 - 19:42

            @Alpine58: Good point about ducted requiring return air which means rooms with shut doors will decrease performance.
            Another thing to check is roof insulation after anyone’s been up in the roof, if the batts are all over the place it’s going to affect your comfort.

    • Mokr on 09/05/2023 - 08:52
      +2

      Disagree the heater if it's oil based feels warmer as it radiant heat. The floor will feel warner

      Air con is just the air.

      • Jimothy Wongingtons on 09/05/2023 - 08:55

        True - yeah we just have the standard fan based heater

  • MS Paint on 09/05/2023 - 08:33
    +41

    My partner has floated the idea

    She is one smart cookie. Don't let her go.

      • MS Paint on 09/05/2023 - 10:42
        +112

        I spoke when I should have woke

          • brendanm on 09/05/2023 - 16:25
            +20

            @FirstWizard: I'm out of negs for today, assume this is one.

          • OzzyOzbourne on 10/05/2023 - 20:42
            +7

            @FirstWizard: Nice of you to be offended on the behalf of the op's partner. 🙄

              • Cusack on 11/05/2023 - 12:22
                +7

                @Chandler: FirstWizards 2nd comment makes it clear it’s about ‘inclusion’. Clearly wokeism

                • Chandler on 11/05/2023 - 12:38
                  -7

                  @Cusack: Perhaps.

                  From FirstWizard's 2nd comment:

                  it doesn't hurt or cost to be inclusive

                  I read that in the same light I treat it: it doesn't hurt to be agnostic. It can hurt to not be.

                  Not going to comment further as that will be a distraction to the true purpose of this thread.

                  I also read this as not pushing the issue further, which (IMO) most woke people would keep pushing.

                  • Cusack on 11/05/2023 - 16:47
                    -1

                    @Chandler: Read between the lines to see someone’s true intentions.
                    This person is clearly woke, or a troll trying to get attention and a reaction. Both the same sad thing

          • lookingforTV on 10/05/2023 - 20:59
            +3

            @FirstWizard: Is your name meant to be FistWizard?

          • Cusack on 11/05/2023 - 07:51

            @FirstWizard: Well done. Do you feel better about yourself now?

            • Kangal on 11/05/2023 - 16:04
              +1

              @Cusack: " There are no girls on the internet "

        • loropy9 on 09/05/2023 - 16:15
          +28

          I think it's just the cold weather generating more snowflakes…

        • solidussnake on 11/05/2023 - 06:29
          +6

          Agreed, now let's all sit around and enjoy some Bud Light 😂

      • Almost Banned on 09/05/2023 - 11:24
        +4

        Pretty safe assumption given the numbers.

  • pao2x on 09/05/2023 - 08:41
    +22

    1) Yes, more comfortable and cheaper
    2) I would try to remove it from direct sunlight
    3) The jump in cost in aircons from 2kw to say 5kw is minimal especially as they cost the same to install, also an over capacity aircon is efficient compared to an aircon working too hard.

    • JohnnyB.Cheap on 09/05/2023 - 11:14

      Thanks for answering all the questions. Obviously not in direct sun is best however with the location of our apartment there are limited options.

      • randombrick on 09/05/2023 - 12:22

        It is probably more efficient for heating to have it in direct sunlight during winter.

      • Love a bargain on 09/05/2023 - 12:27
        +1

        Set up some sort of shade if you can

    • od810 on 10/05/2023 - 17:58
      +1

      I wouldn't install a 5kw in a bedroom. It is a waste. The 5kw base load will be higher than the 2.5kw

      My general rule is to use 2-2.5kw for 10-12m2 bedroom. 5kw for up to 30m2

  • bertts on 09/05/2023 - 08:46

    Would it create mould in winter?

    • MS Paint on 09/05/2023 - 08:49

      How?

      • Jimothy Wongingtons on 09/05/2023 - 08:54
        -1

        Heating and cooling cycles leading to moisture build up

        • MS Paint on 09/05/2023 - 09:06
          +7

          That's why I don't have mould. Never let the house cool down.

          taps temple twice with index finger

          • Jimothy Wongingtons on 09/05/2023 - 10:15
            +1

            @MS Paint: this is the way to do it

            • dtc on 09/05/2023 - 12:53
              +1

              @Jimothy Wongingtons: ah, no - true Ozbargainer is never let the house heat up

              • juki on 11/05/2023 - 23:06
                +1

                @dtc: no once i have finished cooking with the oven i leave the door open to help heat up the place

    • JohnnyB.Cheap on 09/05/2023 - 10:21
      +13

      I believe this is combated by Aircon dehumidifing the air

      • Transient on 09/05/2023 - 13:10

        Also, some air cons have an anti-mould feature so when you press stop it stops cooling but runs the fan for several minutes to help any condensation dry off.

      • howcan on 10/05/2023 - 20:22
        +3

        FYI, air cons don't dehumidify in heating mode.

        • JIMB0 on 11/05/2023 - 09:17
          +1

          The relative humidity will go down as the temperature goes up, but this effect would be the same with any heat source.

      • Dogsrule on 10/05/2023 - 20:34
        +3

        Reverse cycle A/C's do not dehumidify while operating in heating mode as the temperature of the inside coil (evaporator) is not lower than the dew point of the inside air.

        That being said, the action of heating the air will prevent moisture condensing on surfaces, which prevents mould growth as long as the air is kept heated above dew point.

      • Keplaffintech on 11/05/2023 - 11:30
        +1

        The aircon does not dehumidify the air in reverse cycle mode.

        It heats the air, which lowers the relative humidity. However a lower relative humidity also allows for more moisture to enter the air (e.g. from humans, steam, drying towels etc). Then when you turn off the AC, and the temperature falls, all this extra humidity leads to a high humidity environment, and potentially condensation on cold surfaces.

        This is not unique to AC heating though, any heater can create this problem.

  • Sinnerator on 09/05/2023 - 08:50
    +50

    Build a man a fire, he will be warm for a day.
    Set a man on fire, he will be warm for the rest of his life.

    • KSMLJ on 11/05/2023 - 19:22
      +3

      Username checks out!

  • Donaldhump on 09/05/2023 - 09:00
    +4

    i use reverse cycle and its cheaper than a heater electricity wise in the long run, plus more comfortable.
    once it gets balls cold i use a fire place.

    its a good investment in QoL

    • bdl on 09/05/2023 - 16:20
      +4

      If it gets balls cold I suggest thermal underwear

      • Donaldhump on 10/05/2023 - 08:54
        +3

        i like to get my boys free to party through the night.

  • seannami on 09/05/2023 - 09:46
    +2

    I have a single large reverse cycle and a ceiling fan. I also have a little fin oil heater I haven't turned on in 2 years, and an electric blanket. The reverse cycle is on most days as a heater. I much prefer to the gas ducted and gas wall furnaces I've had in past houses, it feels like it distributes the warm better and is less dry and stuffy. Downside is it does kick up the cat fluff and some outside pollen so I can get a bit snuffly with it on.

    In summer, I have the RC on and the ceiling fan on to help distribute the cool air. The ceiling fan is right in front of the RC. Also means I can have the RC up higher (so about 25-27 or so in summer) and its quite comfortable, and less freezing if you are sitting on the couch right in front of it. I will be getting RC in the bedroom and office when I can afford it, need to put in a few other things first.

    I wouldn't go back to wall furnace, even if the one that's here magically stops being a death trap…

    • JohnnyB.Cheap on 09/05/2023 - 11:15
      +1

      Appreciate the response. We do have a gas outlet so while not my preference it was an option

    • JimB on 09/05/2023 - 11:53

      "Downside is it does kick up the cat fluff and some outside pollen so I can get a bit snuffly with it on."

      Outside pollen?

      "In summer, I have the RC on"

      RC means heating. You have the AC on in summer.

      • seannami on 09/05/2023 - 12:22
        +2

        I'm not sure if the motor outside is drawing air/pollen in, or if something else is setting me off, but there's definitely more sniffles on days the unit is on

        And my bad, thought RC was the unit, not the mode

        • JimB on 09/05/2023 - 14:13

          must be something else, unlike cars or gas heating, airconds in houses don't draw outside air in.

          It does however circulate air.

          • ConsumerAffairs on 09/05/2023 - 16:54

            @JimB: A split system won't draw in air due to the separated units, but a window/box unit can via the fresh air/recirculation vent.
            Don't worry, I was thinking the same thing too.

        • ConsumerAffairs on 09/05/2023 - 17:00

          Is it a window/box unit you have? If so, there should be a small lever/switch just inside the outlet vent that will say recirc or fresh on it. Just flip it over, and it should stop your issues of sucking the outside crap in.

          • seannami on 09/05/2023 - 19:52
            +1

            @ConsumerAffairs: It's a split system on a pump (indoor unit is in the center of the house). The motor is directly under the most pollleny tree I have ever encountered. Thanks, though. I guess it might just be dust and cat fluff blowing around and making me sneezy.

            If you wanted an investment tip, Telfast :p

  • JimmyF on 09/05/2023 - 09:51
    +7

    Air Conditioner as heater for winter

    Fun fact, Air Conditioner doesn't mean COOLING like most think, it means conditioning the air, in most case cooler or can be warmer too.

    Your fan heater will use 1200-2400w of power when running non stop. Your split system will use way less over an hour once the room is warm.

    So yes, do this.

    • Donaldhump on 09/05/2023 - 11:07
      +11

      can vouch this

      went to india in mid twenties, in middle of winter and they asked if i wanted an A/C carriage on a train. i said no as i thought it ain't hot at all, who tf needs an air con.

      sat on train for 16 hours through the night freezing my nads off

      saved $1.80, winning

      • JohnnyB.Cheap on 09/05/2023 - 11:41
        +2

        True bargain if there ever was one.

      • Typical16-bitEnjoyer on 09/05/2023 - 13:34
        +10

        TIL Train carriages had A/C in the 1920's

        • Donaldhump on 10/05/2023 - 08:55
          +2

          I am 99 years old so both interpretations work

    • od810 on 10/05/2023 - 17:59

      My 2.5kw split system will pull about 300-400w continuously when i set the room to 23 degree, yeah heaps better than electric heater.

  • Drakesy on 09/05/2023 - 10:22
    +7

    Air cons from memory are 3 times more efficient than an electric heater, so likely will pay for itself over 6 or so years.

  • bargaino on 09/05/2023 - 10:26
    +6

    For people that chose the bottom end of the range do you regret it or is it serviceable?

    It is better not to get one too big. The right size is quieter and more even, less stop/start. Even inverters have a minimum power level.

    Did your old 2400W fan heater heat the room OK? Then a small 2500/3000W split will be good. That is the output power, it will only consume 500W of electricity.

    A big open-plan area needs more, unless very well insulated, which is not the norm in Australia.
    You can save a bit by getting a window/wall model and installing yourself. But split is better if you are staying a while.

  • brendanm on 09/05/2023 - 11:04
    +2

    I also refuse to use fossil fuels to directly heat my home.

    Where is your power coming from?

    • kolorijo on 09/05/2023 - 11:23
      +14

      Indirectly from fossil fuels

      • Almost Banned on 09/05/2023 - 11:27

        Yep - this was my question.
        Why is OP ok with indirect use of fossil fuels, but not direct?
        Maybe they can get rooftop solar as well to help offset?

        • JohnnyB.Cheap on 09/05/2023 - 11:40
          -3

          Answered already, no need to derail the thread.

    • JohnnyB.Cheap on 09/05/2023 - 11:25

      Thought I'd cop this comment so I specifically put 'directly' in that sentence.

      There are no partly combusted hydrocarbons in my room as a result of whatever energy mix my provider delivers. There is enough pollution from traffic, I don't need an exhaust inside my house.

      • brendanm on 09/05/2023 - 13:23
        +2

        You didn't state at any point that you even have gas available, so seems a strange comment.

  • tmcn85 on 09/05/2023 - 11:30
    +1

    Fossil fuels enable the comfortable life you live.

    • turbochris on 10/05/2023 - 08:32
      +1

      Said the frog in the pot…

      • tmcn85 on 10/05/2023 - 09:50
        -3

        You would be dead if it were not for fossil fuels, nor ever born.

        You want to reduce fossil fuels without admitting that you want to reduce life. To make it simpler, people will die not because of fossil fuels but for lack of them.

        This is on people like you who live such a comfortable life that you cannot imagine that situation ever changing. It wont just be other who bear the cost of your fantasy.

        • RefusdClassification on 11/05/2023 - 13:43
          -5

          People should read "Fossil Future" by Alex Epstein, or "The Moral Case for Fossil Fuels", to counteract the eco-fundamentalist propaganda they have been fed. People are constantly making predictions about an apocalyptic end to planetary life, and all of them have been wrong. On the 9th May it was 7 Celcius in Brisbane, 3 degrees below the previous lowest temperature for that day. Global warming is a crock of schitt. And don't get me started on the cretins who assert global warming causes cold weather.

          • tmcn85 on 11/05/2023 - 14:17
            -4

            @RefusdClassification: Unfortunately very few do any in depth reading, and I would guess the bulk of those who do are from the “educated” background who only read with blinkers from their approved list.

            Third level indoctrination.

          • Flying Ace on 12/05/2023 - 07:55
            +3

            @RefusdClassification: Ah the cry of the climate-change-denier: "Global warming is bullshit - because on this one day this year it was COLDER than it was last year!!"

            • Danstar on 12/05/2023 - 08:57
              -2

              @Flying Ace: Sort of like when it’s a hot day and climate change extremists say “see how hot it is? Climate change is real” but then don’t realise it’s the hottest day since 1910 and their argument is gone

  • firestormx on 09/05/2023 - 12:49
    +8

    Definitely worth it. I had our old gas ducted system removed last year and replaced it with 2 multi-splits with 3 heads each (1 for each room/space in the house).

    Power usage is a lot lower as the air conditioner is a heatpump that moves heat instead of burning gas or turning electricity into heat. Previously we would only run the gas heating on freezing days, whereas we now run the air conditioner on most cold days and it doesn't break the bank. Planning to put in some solar panels so that we can use the electricity generated to cool/heat the house during the day.

    This video explains how they work really well: https://www.youtube.com/watch?v=7J52mDjZzto

    In general, keeping the outdoor unit out of the sunlight is a good idea, but it depends on the installation and how the installers can route the refrigerant pipes, so I wouldn't stress too much about it.

    My suggest would be to go for a better unit than the cheap ones (we went with Mitsubishi Electric) as these are things you want to work reliability and not spend time organizing for trades to get fixed. Another thing is to look at the specs for each unit and look at the COP for your climate zone and do comparisons from there.

  • Transient on 09/05/2023 - 13:16
    +1

    My partner has floated the idea of instead of $300 spending on running the thing we spend ~$1700 (unit+installation+energy) to switch to a reverse split system.

    Not really $300 as the cost saving should be ($300 - cost of running a/c instead in winter) x number of years you intend to live in the same place. So not a one year comparison as you save each year you use a/c to heat instead of Kmart heater.

    • JohnnyB.Cheap on 09/05/2023 - 14:58
      +1

      Yes, I expect it to take 7 years to and actually start 'saving' money . Hence not approaching it from bargain perspective, rather a QoL one. That being said I don't necessarily want to make the wrong decision and have it never pay off.

      • Transient on 09/05/2023 - 17:51
        +3

        A/C for Australian summers is pretty much an essential for QoL for most houses. Paying it off through cost savings is a bonus.

  • mrkorrupt on 09/05/2023 - 13:20
    +2

    I believe it is always the best to oversize the aircon instead of skimp as the install cost is generally the same and the one with the more power will 'throttle' when not required instead of working all the time.

    • Sega on 10/05/2023 - 10:38
      +1

      Perhaps, but not necessarily. 1 lge unit to do a whole house won’t be as good and a couple of smaller units in specific areas. Yes install costs are same. But it will throttle based on the temp at the source, and if expected to cool/warm an area at a further location, it won’t. What people tend to do in this situation is turn it up/ down which runs it more to no effect (at the far location).

      In this scenario, 2 correctly sized ac units is better. In any case, a correctly sized ac will throttle when it reaches the temp setting on the thermostat, and both will engage to maintain that temp.

      Correctly sizing to the area is how to achieve the best cost benefits.

    • skillet on 10/05/2023 - 19:02
      +1

      Oversize will throttle too often then it will break down earlier. Also you won't get dehumidifier working properly. If it's variable compressor then by all means go oversize.

  • AustriaBargain on 09/05/2023 - 13:30
    +2

    Heat pumps in split systems are meant to be very efficient. A normal heater will use 1 unit of electricity or 1 unit of gas to make 1 unit of heat, but apparently heat pumps will use 1 unit of electricity to make 3 units of heat somehow. Plus no risk of carbon monoxide poisoning from incomplete combustion of gas.

    • ESEMCE on 09/05/2023 - 14:13
      +1

      It's in the name, they're a pump.
      They're using electricity to move the heat energy from the outside to the inside.

  • Cluster on 09/05/2023 - 14:17
    +2

    I have always had a reverse cycle air con and love them. The heat in winter is pleasant and ducted through the house. Running costs are much lower than any other form of heating. You get a 5:1 ratio of heat energy versus consumption, compared to 1:1 for gas/electric.

  • Motek Benzona on 09/05/2023 - 14:21
    +2

    Reverse air set to come on at 5.30, goes off at 7.40 in the lounge and alexa turns on the bedroom one at about 4.45am.. keeps the house warm for hours. I hate those crappy small heaters

    It does not seem to cost that much (Brisbane)

  • loropy9 on 09/05/2023 - 17:05
    +2

    I've been using ACs for heating for the past forever years and it's been a great experience.
    Cheaper to run than anything else.
    Keeps the air dry and filtered - you need to wash the filters every 6-12 weeks.
    There is a simple formula to calculate the AC size based on your room size - easy to find this on Google.
    Currently have 4 individual ACs in the house. Installer advised against ducted because if the main unit breaks you lose heating in all rooms until it's fixed. Also ducted is much more upmarket i.e. expensive.

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