Water heating; Electric vs Gas or other options?


I have a 315L electric water heater thats 20+yrs old so i suppose it is pretty near to its end of life. I also hv gas in house for cooking and heating in winters.

Wondering when i replace the water heater, should i swap with an electric one or go continuous gas heater? The water heater is running on off-peak costs about $25 monthly. I had a plumber come to quote for instant gas heater and he tells me its hard to do as water pipe needs to be upgraded to thicker one for instant heating and as the pipe is in the walls will be expensive proposition for instant gas one.

So option is to replace with electrical or get continuous gas? Question i have is will continuous gas water heater be much cheaper in runnings as I will hv to pay more for that install ($500-600) vs just replacing electric.

thanks so much



  • +1

    If you have to upgrade your gas pipe, continuous gas will not be cheaper.

    Gas tank might be cheaper than electric tank depending on your utility rates and how long you spend showering and the number of people in the house.

    • Gas pipe doesn't need replacing as that work was done some years back. For instant gas, its the water pipe that is half inch and needs to be 3/4 inch.

      For continuous gas, need to connect to existing gas pipe.

      What i am not clear is how cheaper is gas heating vs electric heating i.e. if i pay $25 / month for electric heating today (offpeak only) - with continuous gas heating how much will it be ?

      • Maybe you got it the other way round because to upgrade to instant gas, it's the gas pipe that need to be upgraded to deliver enough gas to heat water enough. Last time the plumber I saw say it costed 3k for the switch to gas storage to instant gas.
        The cheapest option of all over long term is heat pump, it can come with some government rebates too depending on where you are.

        • Have discounted the heat pump due to significant upfront cost of around $4k and warranty only of 5yrs.

          The plumber said gas pipe has been replaced - its the cold water pipe for the water pressure that need to be replaced with a thicker one.

          I hv got another plumber looking next week so will know

  • +2

    Like for like will be the easiest option.

    If you're going to invest in the additional $500-600 to change the system, then do your math to see if it works out for you/family over the time you expect to live there.

  • Replace like for like - make sure it has a long warranty

    However, I once bought a instant gas hot water which only started heating once the water was flowing through - paid little even on gas as no gas was being used during the day etc

    Replacing to a new energy format will cost more money - electricity prices will go up for sure (i guess gas will too)

    • How about something like Solahart heat pump - are they good for Sydney?


      • That will be the cheapest options over long run because they'll use a quarter of the amount energy or even less. But the set up cost will set you back by 4k or so.

    • -1

      Electricity prices are not going up, they’re on a long term downward trend due to renewables taking up more and more of the generation capacity.

      We replaced our old working gas hot water tank with an instant gas unit. It’s a 6 star Thermann one (made in Japan). We have a small townhouse so switched to this because it’s much smaller to reclaim some backyard space. It’s been really good. Gas bills seemed to go down a bit too. We had to get the gas line upgraded to 3/4” as well.

      In my opinion you would only go electric if you have solar panels. To use the spare extra capacity rather than feed it into the grid.

      • +1

        I spoke to a plumber he tells me electric off peak vs gas storage is almost similar cost of running. As such, I have decided to leave it as electric off peak as it is a straight swap and longer life plus more safer.

        • Fair enough, I haven’t got any figures to confirm or dispute it. At least in the future if you get solar PV panels you can heat your water with the energy generated by that.

          • @GeneralSkunk: I have already got solar but if gas instant wud hv been able to be worked - I wud hv gone with it given energy is being used when we need it rather a tank being heater unnecessarily all day !

  • +1

    Where is your nearest public park with BBQ facilities?

  • We chose continuous to free up space from an old gas heater but the side benefit we didn't know at the time was the use of temperature controllers. We hardly ever mix hot and cold any more as we set the correct temp in the bathrooms and kitchen; ideal when you have kids and can set the shower temp at 37-39 and no chance of burns or wasted water getting the temp right.

    • Yes unfortunately for me instant gas heater is not an option it seems !

      • So you can't get one of the smaller continuous flow gas heaters (say Rinnai 16)? I had one of these at my previous place and it handled 2 showers on the go at once. Is it definitely the water pipe that needs upgrading and not the gas? Is the gas a 1/2" or 3/4"? Gas is certainly a cheap option if you've already got a mains gas connection - about 3/4 of our gas bill is the supply charge rather than the gas itself.

        • Plumber said the gas pipe was upgraded but the water pipe needs to be upgraded - with instant gas heaters the water is not as hot as storage system so the pressure will be low if water pipe is not upgraded…he was worried that i will complain hence was upfront about it…

          "….about 3/4 of our gas bill is the supply charge rather than the gas itself." this is interesting for me…is that for a family? If so, it means gas consumption is only 25-30 per quarter?

          • @CheapSticks: I just relooked at my last bill and my comment was swayed by a discount they applied…but for a family of 5 we average between $60-$90 per quarter in gas, which includes a Rinnai 26 and gas cooktop which gets used a lot. The point about the storage heater makes sense - they do store at a lot higher temperature than the required flow.

          • +1

            @CheapSticks: I'd get a second opinion. Plumber is scamming you.

            I've never heard that the hot water pipe needs to be bigger and I've built a couple of houses with instant continuous gas hot water.

            Are you in VIC? If you change from Electric storage to solar hot water, you can get a rebate of $1,000 from State Gov. Plus rebates for STC from Federal Government.

            I have solar hot water with instant continuous gas hot water. Great combo. Barely any gas consumption in Summer, in Winter I'm not paying for gas to heat up a large water tank.

            • @JimB: Thanks @JimB - its the cold water pipe size thats needed to be larger to ensure say two taps being used simultaneously can be serviced.

              Your set-up sounds great. I will anyhow get another plumber to come and have a look.

              Seems like going gas storage may be the way or just swap with electrical.

  • I replaced my enamel, electric water heater with a stainless steel one with solar hot water (30 Apricus evacuated tubes - 45 would be better). No need to boost in summer unless below 24 degrees. In winter, boost every other day. Also using OP 2 helps reduce costs. OP1 even more so but cannot boost during the day.

    • Very expensive mate - $4-5k

      • yeah, was cheaper with gov rebates - brought it down to $3k. Using it for more than 10 years. Paid itself off after about 4 yrs, so more of a long term thing.

        • ok thanks - I hv put in a call to a sales rep to understand the warranty - want to make sure it covers 10yrs at minimum to spend that upfront amount.

          • @CheapSticks: Also bear in mind, if your area gets large hail, could be a problem (although it is fine against small hail). Also had to replace the pump after 8 years - cost about $200 + plumber.

            • @Transient: I had a rep come and he quoted $6k for it after rebate….can you pls PM me the trade you used to install it…

              • @CheapSticks: Had a look through my papers but can't find it. It was back in 2011 so will need to look through my archives over the weekend. From memory, Apricus was pretty new and small so I think I contacted them direct and they sent a rep out for a quote. I was happy with it so they used one of their contract plumbers to install. I didn't separately arrange for the installer. Was arranged by the rep. I remember the plumber was good as had to reroute a stormwater pipe to fit the new HWS. Wasn't part of the quote so only charged me about $20 - the pipe was non-standard so I bought it from a nearby Tradelink. I kept his number for at least 5 years but when I tried it, he had moved to the outback. So maybe any plumber with Apricus experience can quote to install?

                Seems the price has gone a lot higher in 11 years! Our neighbour has the flat plate solar heater which is cheaper but from reading they have their own problems especially if you live in Vic or other places where it gets colder.

  • I recently installed a iStore Air to Energy heat pump to replace an old off-peak electric tank. I got the 270L model and cost me just under $3k installed (in Sydney). They seem to be coming down in price. Works great. It’s got a built-in timer which I’ve setup to run during the day when my solar panels are cranking.

    • thanks - sounds like a great product however the warranty of 2-5yrs is no go for me given upfront investment amount.

  • You can think about solar water heater system. They’re worth it for a small family and you can enjoy larger savings by reducing monthly utility bills by 50 to 80% on an average. They can pay for themselves very quickly.

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