Running costs and experience with ducted reverse-cycle 24KW unit

dshamim on 03/12/2021 - 11:45

Interested in finding out if anyone has Rinnai DONSR24Z9 / DINLR24Z 24KW 3-phase or similar ducted reverse cycle unit and how their experience has been ?
I'm more concerned around running costs especially for heating - place is 38sq, 2 storey with 4 heating / cooling zones - windows are all double glazed but we do have 3 large 3-pane entertainer doors that are not double glazed

reason we didn't get gas heating because the way the builder was proposing the zoning on it - we couldn't shut off the ground floor, it would always be on regardless , we hope to offset some of the cost with solar but just getting a general idea here with other peoples experiences

Electrical & Electronics Air Conditioner Rinnai

Comments

  • MS Paint on 03/12/2021 - 11:48
    +1

    That is a beast of a unit. What was the install cost if you don't mind?

  • dshamim on 03/12/2021 - 11:49
    +1

    been quoted 23k as part of the build - inclusive of 3phase wiring setup

    • MS Paint on 03/12/2021 - 11:59
      +2

      Cheers. I've got a 15kw single phase ducted system into 5 zones, single storey 30sq home.

      The heating was pretty expensive to run over winter (wife feels the cold running it 17 hours per day) but later installed a huge wood heater that we burn 24/7 for 4 months of the year (unlimited supply of redgum on property) so haven't used heat option very much. Sorry.

      In summer you just can't beat them. I find the cost acceptable over summer (no solar panels) and it shits all over evaporative cooling. No windows to open etc and not disrupted with high humidity). The only times the unit has struggled is a string of 40+ days and hot nights.

      • JimB on 03/12/2021 - 12:41

        Wood heater/radiant heating is so much nicer than RC heating.

        The fact it's free is just icing on the cake.. very jealous!

        • MS Paint on 03/12/2021 - 12:47
          +1

          The whole house remains toasty as long as you keep feeding the beast. We walk around the house in tracky dacks, t shirts and barefoot all winter. It's awesome. Collecting and splitting wood takes time (so technically not free) but it's just part of my winter fitness regime (so I keep telling myself anyway 😀)

          • JimB on 03/12/2021 - 13:08

            @MS Paint: Fantastic.. I'd do the same. Is it a closed or open wood heater?

            If I had access to free firewood, I forgot the name but I'd build a huge oven like fireplace surrounded by lots of bricks. The bricks are used for thermal mass and will radiate heat for a couple of days. I found it fascinating.

            Myself, I have hydronic heated slab.. so also go barefoot in winter. If I had free firewood, I could also incorporate a wood fired boiler to heat the water in my hydronic heating system. as it stands, I use gas.. not cheap but it's fantastic walking around the house barefoot with no cold drafts. I put a jumper on but kids are happy in a t shirt.. haha

  • bloom on 03/12/2021 - 11:55
    +3

    Get solar, payback will be pretty quick assuming someone’s usually home

  • MrHyde on 03/12/2021 - 12:02
    +1

    We've got a 17KW unit. We've got it set up with 6 zones. When in use, we usually only enable max 3 zones. When that happens, our power consumption hovers between 4-5KW as per our consumption monitor. Our solar easily manages the cooling side; but when heating; solar is usually not generating much - so more expensive in the winter months.

  • pegaxs on 03/12/2021 - 12:17

    Holy crap. What are you cooling, a shopping centre?

    I have a large house and only a 3 phase 7kw system and it's freezing in summer. And that 7kw system sucks down power like a yr 7 kid sucking back cans of monster energy drink. I hesitate to think of how fast a 24kw system would drain your wallet

    • dshamim on 03/12/2021 - 12:28
      +1

      no idea :/ the builder only has Rinnai for reverse cycle / air cons installation partner - the design was I think proposed by them

      https://www.rinnai.com.au/wp-content/uploads/Rinnai-DRCi-20kw-24kw-Brochure-WEB.pdf

      the other options were gas ducted - 2 zones, in which we could never shut off 1 zone on the ground floor
      or hybrid, electric cooling and gas heating with above limitation on zoning, which was maybe about 5-7 k cheaper option

    • MS Paint on 03/12/2021 - 12:30

      3 phase for 7kw?

    • JimB on 03/12/2021 - 12:43
      +1

      7kw is small for a ducted unit.. there's no real point getting 3 phase for only 7kw.

      • pegaxs on 03/12/2021 - 13:37

        Don't know. It's what the house came with when I bought it. The only thing that runs off the 3phase is the A/C. (I've since added a 3phase solar inverter and panels)

        It is a ducted unit and is split into 5 zones across 7 areas and even on stinking hot 40+ degree days, I've had to dial the temp up because it's freezing inside the house.

  • JimB on 03/12/2021 - 13:00
    +2

    I have a Daikin 20kw 3 phase. 34sq home. 2 zones.. top storey and ground

    if we need air cond…. we only use it on the top storey 90% of the time as the ground floor remains cool at 22-23 degrees on all but a few weeks of the year.

    So running only the top storey at say 22-23 degrees from the afternoon until bedtime, say 5 hours a day. The first hour will use about 3-5kw and then once it reaches 22-23 deg, it will ramp down and use about 1.5-2.5kw per hour.

    I don't have solar yet and while it's not cheap, it's not expensive either. I'm not going to spend $16k on an aircond system and then worry about $2-3 a day of electricity to remain cool.

    I didn't care for many zones either.

    All bedrooms are upstairs.. so either all bedrooms are cool or none.

    Ground floor, either all or nothing which doesn't bother me.

    The problem with multiple (6-8 zones) is that say you only want 1 bedroom on. A large aircond will still use quite a bit of electricity as it can't ramp down that much, plus, were is the return duct? The common zone is hot, so the AC system still will draw hot air and cool down the common zone over time.

    • fantombloo on 03/12/2021 - 13:21

      All bedrooms are upstairs.. so either all bedrooms are cool or none.

      I have the main on a separate zone. Sometimes it needs to be warmer or cooler in the main while the kids are asleep, if that makes any sense.

      • JimB on 03/12/2021 - 16:25

        that's a good point but we don't leave it on overnight though.. we turn it on in the evening for a few hours and open all the bedroom doors.

        Once the kids go to bed we turn it off and by then it's cool enough not to require a/c to left on overnight.

        • fantombloo on 04/12/2021 - 07:27

          Seem to be missing the point so I'll just spill it: the main room should have it for sex.

          On a cold night when the kids are already snug asleep you want to be able to turn it on in your room so you can play around without a thousand blankets in your way. On a hot night when the kids are already asleep in their nothings you want to be able to turn it on in your room so you can play without becoming a dripping mess.

          • JimB on 06/12/2021 - 20:45
            +3

            @fantombloo: Yeah, not worth it just for my birthday.. haha

    • dshamim on 03/12/2021 - 13:28

      same, we have all bedroom upstairs, with 2 zones - 1 for activity area and 3 bedrooms, 1 for master bedroom and walk in wardrobe and bathroom (it's a big space combined)

      ground is 1 zone for common open space living area/ meals/ kitchen , 1 zone for study, theatre / corridor

  • MikeKulls on 11/12/2021 - 19:26
    +1

    We have a 19kW unit and it's fairly pricey, several thousand per year to run. Our house isn't that efficient though. On another note, you should consider where you are going to put the return air vent. You can't avoid heating/cooling the path back to the return air location. If it is downstairs and you want to turn that zone off then the area will still get a lot of heating or cooling.

    • dshamim on 24/12/2021 - 18:28

      Can I ask, if if its an older build ? from my understanding is that new houses are supposed to be 6 star energy compliant - unfortunately planning for us is out of the question, was designed by builders partners -the path back is on the ground floor

Login or Join to leave a comment
Login Join