Options for Switching Hot Water from Gas

profane01 on 18/11/2023 - 17:20

Hi OzBargainers.

Long story short, I'm going to be disconnecting my gas and going solar/electric only at home. The main things I'll need to change are my cooktop and hot water system, and I'm after advice on a hot water system.

The cooktop is pretty easy as I feel that induction is clearly the the best option there.

However, I didn't realise there were so many options for hot water systems, and I was hoping to hear about some experiences. Tradies I've spoken to have differing opinions and some appear to be pushing a particular product/brand, which makes me sceptical.

Note:
- I'm in Adelaide, so I won't get as many frosty mornings as Canberra/Hobart
- I have a solar PV system which provides me ample power which is mostly being exported to the grid

These are the options I'm considering:
- Flat plate solar system
- Heat pump hot water system
- Electric storage with solar diverter

I feel that the flat plate solar system would be best if money wasn't a concern, but the initial outlay is quite steep (note that due to the climate I don't think I'd need to consider evacuated tubes), and I feel it would take a very very long time to "break even" cost-wise.

I've read a lot of good things about the heat pump systems, but my main concerns are:
- Noise
- Availability of experienced technicians
- Small warranty period/shorter life
- Performance in winter
- Costs of repairs/maintenance

A stainless steel twin element storage system with a solar diverter (and timer) is the other option I'm considering. I feel that these units are proven to last a long time, and if I had to replace the heat pump system after 5-15 years, I'd be better off going with this option.

Breaking down the costs (roughly), I figure that these would be the initial amounts to outlay:
- Solar $4000-8000
- Heat pump $2500-5500
- Electric $1500-3000

So, based on the excess solar I have, I feel that there wouldn't be a great amount of energy savings with the solar/heat pump options. And the fact that electric systems are proven to last a long time, I feel it is a smarter decision to lean this way.

But I'm no expert, and I've never used any hot water system other than gas in the past. So I'd love to hear thoughts and/or experiences. I'd also love to hear recommendations on brands too.

Sorry for the long post!

Cheers

Home & Garden Hot Water System

Comments

  • mskeggs on 18/11/2023 - 18:45

    I replaced a solar flat plate this year with a traditional electric storage wired into the normal meter (not off peak).
    The thermal flat plate solar are now absurdly expensive, and the one I replaced was under 15yro, coincidentally, the numbers showed a new one would pay itself off in 12 - 15 years. Hmm.
    I've heard mixed reports on heat pump hot water reliability. The power savings are definitely substantial, but if I am generating plenty of solar anyway the opportunity cost of putting extra kilowatts into hot water versus the grid feed in tariff is small. A heat pump hot water might take several years to make savings over a traditional storage system if the operational cost is 6c per kWh.
    I also figured the warranty on a traditional system was 10 years versus max 5 years for a heat pump.

    I expect my next hot water system will be a heat pump, and buy then I expect they will be very mature technology at very competitive prices.

    • mskeggs on 18/11/2023 - 19:24

      Sorry, I forgot to say the new system is on a timer for the middle of the day so it is when solar is peaking. Haven't run it through a winter yet, but I expect it will still be predominantly powered by solar, but if there is a very grey day I can live with paying grid prices for hot water that day.

      • profane01 on 18/11/2023 - 19:48

        Thanks for the response. It seems on par with what I'm thinking. And yeah, the heat pump technology will be much more common and robust in 15 years time than it is now and may be the way to go

  • gudplr on 18/11/2023 - 20:09
    +2

    Go the heat pump. They use the least amount of energy - 4x more efficient than standard electric. Winter performance and reliability issues were only the case for the earliest models. The technology is mature and they perform right down to minus 15 degrees. The tanks are so well insulated that the inverter can be set to only run during the day, and it'll hold its heat overnight. The noise isn't even that bad.

  • jumpypotato53 on 18/11/2023 - 20:13

    We got the heat pump tank a few months ago. No issues so far. We are in Illawarra NSW. We paid under 3k with the government rebates.

    • mskeggs on 18/11/2023 - 20:50

      I think that $3k cost for a reliable system is the barrier for me. A old school electric uses 4 times the power, but if it is all fed from the solar, it takes a while to pay off.
      Solar costs me 6c kWh in lost grid FIT. I use 6-8kWh for hot water. If I can supply that from solar. 42c a day means a long pay off, even if the heat pump only uses 2kWh a day instead.
      It depends on the feed in tariff staying at least that, and the heat pump lasting the 10-15 years a old school electric storage system lasts.
      I think it is marginal today.
      I’m banking on better, more reliable heat pumps coming along, and likely rebates to take them up for my next hot water service.

      That said, I don’t discourage heat pumps as they are so efficient and reduce carbon costs for people without solar - good news your one is going well!

      • jumpypotato53 on 18/11/2023 - 21:02

        People should also consider the refrigerant gas used in the heat pump. Some are worse than others for the environment.

        I don't have a solar system yet so my choice was straightforward.

        • profane01 on 18/11/2023 - 21:25
          +2

          Very true. I noticed Sanden and Reclaim use R744 (CO2) and a few others such as Hydrotherm and Aquatech use R290 (propane), and they are considered the best for the environment as far as I'm aware. Try to avoid R410a and R134a which are used by EvoHeat and iStore. There could be higher costs involved in the disposal of refrigerants to consider also at the of of the system's life

        • mskeggs on 18/11/2023 - 21:32
          +1

          This is true. I prioritise climate change over waste to landfill as the most immediate issue, but some refrigerants are troubling, but even the worst are better than 10 years of coal burning emissions.

      • igorekh on 20/11/2023 - 14:19

        A old school electric uses 4 times the power, but if it is all fed from the solar, it takes a while to pay off.

        I wouldn't count that "it is all fed from solar" – it would need ~4kw for ~2 hours every day to run it completely off solar. Of course it heavily depends on your solar system (how much it generates) and weather but I doubt it would be possible 100% of the time.
        For my 6kW solar system I guess it would be around 70% mark throughout the year.

  • docpol on 18/11/2023 - 20:22

    Following. I'm also in Adelaide and thinking to do the same.

  • mskeggs on 18/11/2023 - 21:27

    I should be clearer about why old fashioned, Solahart style hot water is such a bad deal.
    Those systems capture the heat of the sun to warm water, and on cold, cloudy days use grid electricity (usually off-peak) to heat the water.
    This means the best they can do is the sun that falls on them.
    The heating plate is about 3.5kW. You need about 7kWh to heat your hot water.
    So on sunny days, it heats fully and any further sunshine is wasted. On grey days, if it doesn’t heat fully, it draws from the grid.
    If you instead have 3.5kW of solar PV, you still get it heated fully on sunny days, but excess sunshine provides power, for your home or the grid. This is a big benefit, probably twice or more the power in sunny times.

    Most houses that can support solar enough to make hot water directly, have plenty of space for extra PVpanels, so you might as well get 6kW, or 10KW of panels, enjoy the power savings and heat your water as well.

    If you don’t have solar, or you have only small solar, heat pumps make good sense.

  • igorekh on 18/11/2023 - 21:57
    +2

    I was in a similar situation, went from LPG to heat pump (Sanden 315L) in 2016. So far it has been working fine. Very quiet, no problems in winter.
    There was a time when FIT was 20c, pretty sure the pump has already paid itself off. I like that it uses less electricity when it's running – only 1kW, so even on grey days it runs off solar panels. It takes 4.5h to heat the full tank but on average it runs everyday for about 2h.
    Happy to answer any questions.

  • bargain huntress on 20/11/2023 - 18:04

    Me too. I have moved to cooler climate and i miss the tank of always hot water i used to have. What is that kind of system called? Do they only work in warm climates?

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