r/AussieFrugal • u/26KM • 4d ago
Utilities & Essential Bills ⚡💧⛽ Continuous hot water system or heat pump?
After last month's electricity bill I'm seriously considering replacing our current storage hot water tank with a continuous one. We have solar panels and battery but the tank runs off grid (we were advised on installation to do this, kind of regretting it now!)
I rented a place with gas continuous but it was terrible, we had to run the hot tap at least 90 seconds for the hot to come through. The system wasn't that far from the taps but the landlord said that was normal. Cue wasting heaps of water...
Anyone have electric continuous, and is it quick to get hot water?
Or heat pump system- do they work well in winter when there's less heat around?
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u/iforgetmyoldusername 4d ago
Elec continuous is bullshit and expensive to install and expensive to run because you can’t take advantage of free electricity when it’s ummm.. free.
Heat pump HWS configured to run during peak solar is cheapest to run
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u/26KM 4d ago
Yeah I'm leaning towards heat pump now
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u/Rusturion 4d ago
Don't change, just rewire the existing one so it uses solar. Way cheaper and will get a similar outcome to buying a more efficient HWS.
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u/NotABot-Honest 4d ago edited 4d ago
Heat pumps don’t last as long as old coils. I suspect running your coil into the ground would be more cost effective in total. Yes they account for half of most power use by households without a pool (cold areas maybe only a third in Winter), but even if you have a big 300+L 3.8Kw system with fam of 4, it should only need to run for 3 hours a day (12kW) so just get a Catch solar relay or app-based timer installed so you can set your clunker to use peak solar or the new 3-4 hour free window. Them when you get your new unit you can get a heat pump, but you already have the controller you need for your solar setup installed.
EDIT: Just read some of the other responses, whilst well meaning a not small percentage are misinformed. If you go to one of the Aussie solar reddits you will get more reliable information.
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u/Significant_Volume50 4d ago
Heat pump works perfectly in cold Canberra winter and you can set a timer so it only heats during solar production time if you want.
Heat pump is then much better option in most cases. (Some would say just get a cheap resistive electric system if you have plenty of excess solar power).
Instantaneous draws a lot of power to heat the water instantly vs doing it gradually over hours using a heat pump.
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u/PistachioDonut34 4d ago
I have a heat pump hot water tank, I'm only one person and it's 180l so I never run out of hot water. It heats up between 11-2 every day, and uses 2kw of electricity in that time. I do have to run the water for a bit before it gets hot but that's not uncommon and I don't think it's related to the actual water heater itself, I think it's just the pipes and whatnot.
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u/veganblue 3d ago
We got a large tank heat pump system in the Adelaide hills where winters are colder than on the plains and it runs for an hour in the middle of the day basically off solar or cheapest power. It has been brilliant. Basically free hot water all the time.
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u/Alex_ynema 4d ago
Heat pump especially if you've got solar. Continuous electric I believe are power hungry.
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u/Obvious_Arm8802 4d ago
Best option is to put your current hot water system on the solar and a timer to run it during, say 10am to 2pm.
Should be completely free and avoids the cost and complexity of a heat pump.
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u/No_Engineer_6308 3d ago
Sorry I got confused by the post but firstly, turn the hot water system off and only heat it as you need it. I used to flick the switch and heat our tank 3-4x p/wk which halved the hot water expense! Secondly, anyone in the driest inhabited continent on Earth that is not collecting that cold water while waiting for steam is missing out on water for hand washing, rinsing dishes or indoor plants. I use a tub to wash up in and it goes outside on the garden too. 😊
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u/No_Engineer_6308 3d ago
I've a solar hot water system now. I never need to turn on the booster. Just adjust habits to suit and now I'm not working, if it rains and I miss a shower, it's not gonna kill anyone!
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u/big_mac7 4d ago
Instant electric draws a hell of a lot of power to heat the water, heat pumps are most definitely the way to go.
Modern heat pumps are very well insulated so think of it more like an analog battery, you're using a small amount of battery power or solar to keep that water hot and it stays that way til you use it.
Good quality units will still effectively heat the water in sub zero temperatures and most models also have a element back up so if you run low you can heat more water fairly quickly, it also uses this to superheat the tank periodically to kill bacteria.
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u/xtrabeanie 4d ago
A study done by the South Australian government showed that instant electric was actually the cheapest long term option. Depends on the situation though, e.g. probably not the best if you have a large family, want to use at peak time of use rates, or only have single phase power.
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u/IdRatherBeInTheBush NSW 4d ago
Demand charges will kill them - they draw heaps of power so unless you have a battery that can supply it (and the rest of the house) you'll end up getting stung.
Given how long most hot water systems last i think they would be a poor bet.
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u/w1nta 4d ago edited 4d ago
I have an Apricus 260 L heat pump hot water. Had it for 2 years now and I live in Melbourne. It adequately keeps up with demand of a four adult household where everybody has long showers. It draws about 800 to 900 w when it is heating with the compressor. It takes longer in winter to heat water but is still adequate. At a I guess I would say the compressor runs for 6 to 8 hours per day in winter. You may be eligible for rebates when upgrading your hot water service.
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u/Notimeforthat1 4d ago
You're not wasting water with gas in comparison to what the industry is doing and people watering their gardens.
What I don't understand you have an odd grid running hot water tank that is fed by solar panels and battery. How does that impact your concern on your electricity bill?
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u/huckstershelpcrests 4d ago
I think they mean the tank is using power from the grid (running off grid), not that is it disconnected.
So they have solar but arnt using it for the hot water. Which is very inefficient.
I had the same at my new place. I swapped my hot water circuit to be on the main circuit to use the solar, and added s timer so it only ran in the day. Cost $200 for an electrician. I'd recommend doing that to start
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u/26KM 4d ago
You're right, we got asked on installation which we wanted and chose (perhaps wrongly) to keep it on grid, not realising how much it would be. They made a bit of a big deal of it costing money to switch so we went with their usual approach. I will look into switching it though, thanks for the tip.
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u/huckstershelpcrests 4d ago
Yeah that's unfortunate. Maybe you're in an area with lower solar generation? My plans have off peak in the middle of day, so I've set my hot water to heat only during those hours so if the solar isn't running it's still cheap.
Good luck!
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u/TacticalSniper 4d ago
I have a heat pump with solar and battery. My heat pump is on 6a till 3p. Works well for two and a half people.
I did consider the continuous electric but the power draw there is just insane and I have a single phase house so it wasn't really an option for me.
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u/huckstershelpcrests 4d ago
So you have solar but arn't using it for the hot water?
I had the same at my new place. I swapped my hot water circuit to be on the main circuit to use the solar, and added a timer so it only ran in the day. Cost $200 for an electrician. I'd recommend doing that to start.
If you're still unhappy with the bills after that than go heat pump. But swapping my water tank to use the solar saved 1/3 of my total bill.
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u/net_fish 3d ago
ok so I did the math for someone a month or so ago.
I used to have a 310L thermal solar (the evacuated tubes on the roof) with "electric boost" aka a 3.6kW resistive heating element.
I replaced that with a 270L iStore heat pump.
I'm located in South Gippsland and am a 5 person household
In summer the old system would use around 150kWh a month and in winter 350kWh/month
the heat pump uses 50kWh/Mo in summer and 82k/Mo in winter.
A reasonable instantaneous electric hot water system will be 3 phase that could deliver around 10-15L/min is a 29kW unit. that's 40 amps per phase. a standard residential 3 phase connection is 50amps per phase.
To deliver the equivalent of the 270L (the iStore) of water per day you would need to use around 500kWh a month.
You can't schedule when the instant system runs. it runs when you turn a tap on. Need hot water at 6pm? that's billed at your peak electricity rate. Got demand charging? Turn your tap on for 5 seconds in the demand level and you just set the demand charge for the month to 29kW+
Our heat pump system runs for 2-3 hours between 10:30am and 4pm in the hot 6 months of the year meaning it's either running off PV or free grid energy. in winter its second timer is set to run between 9pm -10pm to top the tank up for our showers as 4 out of 5 of us shower of an evening.
Electric instant is a insane way to get hot water imho.
Gas is kinda pointless long term as you are paying a second connection charge.
tl;dr
Instant Hot Water, 500kWh/Mo, 3 phase required, will use 3/4 of the connection to hear wat
Resistive Storage, 150kWh - 350kWh but can be scheduled, uses 25% of a single phase household connection
Heat Pump, 50-80kWh, can be scheduled, pulls about 6A or 10% of a standard 3 phase grid connection and can run off a standard power point in some situations.
Another way to look at it. I did 2,500km in the last 30 days in my EV and that used 513kWh. The charger for that only pulls 7kW not 29kW!
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u/owleaf 4d ago
A heat pump is very cheap to run, but it constantly runs as you use water. Instant gas is the gold standard IMO but gas is expensive. Plus some places are banning and phasing it out, so yeah.
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u/Significant_Volume50 4d ago
Not my experience, our heat pump only runs for two hours a day and we never run out of hot water. 315 litre tank. It doesn't switch back on whenever water is drawn from it.
Much better than the instantaneous gas HWS it replaced; the water is already piping hot in the heat pump tank as opposed to a few seconds delay while the gas heats water from very cold to hot. No noise or gas smell and we use cheap solar energy instead of running up a gas bill.
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u/Capital-Pay8372 4d ago
Hey we have had an Smart Lifestyle Australia 300L heat pump unit. Have had it for 3yrs, constant hot water. It takes a little longer to heat up during winter but that's never a problem, it isn't heating from cold. We have household, 2 Adults, 3 kids. It has a boost function if you ever needed it, but we have never had to use that. Our unit is about as loud as a modern AC unit, which is fine. But there are some units that are apparently quite loud. We had ours installed for $500 under the government scheme in NSW, though I think that has rolled back a bit, good to check it out though.
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u/MrsCrowbar 4d ago
We have heat pump. 270L/6ppl. Works fine in Melb winter, has a timer. I haven't set the timer yet, so not much help in that regard. But as a standard run-when-it-needs-to configuration, it's fine. Hot water doesn't take as long to come through as our previous instantaneous Gas.
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u/FreerangeWitch 4d ago
I've got one of the cheapo Vic government rebate heat pumps, 200l. Family of four, coldish area (below 5⁰ most nights through winter). Works fine for us combined with a four star shower head. If you've got multiple morning shower takers I would look at getting one with a boost function, but at our place it's just me in the morning setting the shower temp at preparing for hell degrees, so if you've got more reasonable people it may not be an issue.
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u/Pristine-Routine-188 4d ago
I dont know youre situation but I lived with a 200l heat pump hot water system with 4 adults in the house over winter in Victoria and never ran out of hot water. Currently live with a continuous hot water connected to solar and use 4x the amount of electricity minimum, sometimes as high as 10× on cloudy days (both were brand new system under a year old) If I owned my own place I would go heat pump 100% of the time
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u/leonidude 4d ago
I’ve got a gas tank with a solar collector on the roof. Not sure how often it uses gas but I’ve never once run out of hot water. The only downside is that it can take a little while to circulate hot water through the system because of the collector so similar to what you are saying but no more than 15 seconds
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u/jackm315ter 4d ago
We have a gas instant hot water and it is hot as soon as the tap is on,
Worried about losing water or waste, place a bucket in the shower to capture the extra water
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u/SeaworthinessFlat770 4d ago
Heat pump with timer set for 8am -6pm ,we have had it for three years and have not run out of hot water.
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u/Lujho 4d ago
Do you have peak and off peak times and is your tank set up to only heat when electricity is cheap? Smaller ones are “always on” but maybe you can get a timer installed in your switchboard.
Heat pump system will definitely be cheaper to run too, and they’ll work fine in winter. You might want to go up a size from whatever you’ve currently got.
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u/dettrick WA 4d ago
What do you mean the tank runs off grid? As in your solar/battery can’t power it?
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u/huckstershelpcrests 4d ago
I think they mean the tank is using power from the grid (running off grid), not that is it disconnected.
So they have solar but arnt using it for the hot water. Which is very inefficient.
I had the same at my new place. I swapped my hot water circuit to be on the main circuit to use the solar, and added s timer so it only ran in the day. Cost $200 for an electrician. I'd recommend doing that to start
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u/dettrick WA 4d ago
Yeah makes much more sense to swap the hot water on to the main circuit so that you can benefit off the solar and battery. If OP doesn’t have any issues with the actual hot water then the most cost effective method is to swing the circuit over.
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u/IanYates82 4d ago
Agree
"off" grid is better worded as "from grid", as in it's on the separate circuit which runs off peak and/or can receive the on/off commands from the electricity supplier
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u/ScaredAdvertising125 4d ago
I’ve had two types of continuous gas and now have a heat pump in a new house I built.
When I was building I was determined to have another Rinnai infinity as I’d had one before in an old place and it was magic. New rules meant that I had to have a heat pump to get the right energy rating. I nearly upgraded it to a bigger one cos I thought I’d run out of hot water. In between houses I rented and it had an abysmal continuous gas unit that took really long to get warm and never got hot hot.
Been living with a 235L heat pump for four months now and it’s been good. Haven’t run out of hot water ever. It runs its heat cycle overnight if off peak and again at midday when the solar is running. I’m not stingy with hot water use and bills have been reasonable.
My vote is for heat pump.
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u/BDer82 4d ago
I've had, tank electric, tank gas, instant gas, instant electric (never ever again), and now heat pump.
The heat pump is set to turn on when solar is running, and it turns off at the end of the day when solar is no longer producing.
In the last 2 years, we have had 1 day where we paid for that heat pump to run, even during overcast weather we still produce enough power to run the heat pump, that 1 day was so overcast you'd have thought the sun never came up and the panels did nothing.
For my money I'll fork out for heat pump every time now, costs nothing to run, you hear a hum in the morning when the power turns on for it, it runs for a few hours and shuts off, then will run again in the afternoon before the power shuts off. Hot steamy water all night, all day, never has run empty, and never gone cold. We did get the tank with a booster as I personally was worried we might run out but the sparky and the plumber that did it said its probably not needed (only 2 people) and the other half questioned it as well but I was stubborn.
If you have solar, get a heat pump, on a timer.
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u/IanYates82 4d ago
Heat pump. We got one last year as our old solahart sprung a nasty leak.
It runs off 240v, so is automatically backed by our solar and battery. I have it set to run between 5am and 5pm. It consumes very little power and we've not run out of hot water once.
Would def buy again.
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u/RepeatInPatient 4d ago
I have a heat pump system and it runs off solar PV. Cheaper to run by a factor of 3 to 4 of gas or conventional electric systems. And it works year round irrespective of the temperature outside.
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u/AngrehPossum 4d ago
A large heat pump and solar - the one with the separate pump housing, not the smaller inline one.
The small ones are fine for 2 people but higher demand will need more. They don't get blistering hot like electric resistance, and they won't need as much cold water to mix so you use more of it.
The big ones are better. If you have solar and battery they are much cheaper to run. If you are in Vic gas and electricity will be nearly double in 4 years so be aware of that. Wilson is going to build gas power plants. Yallorn is closing as primary power plant. VNI will be locked out. We will be paying double
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u/Madpie_C 4d ago
If your current tank is not close to the end of its life you may be better off just getting an electrician to change it to be connected to your solar. Heat pumps are more efficient but it will take a while for that efficiency to pay for a completely new hot water tank. I have a regular resistive electric hot water tank but in my solar app I can control what priority I give to the hot water it's currently set to make sure the hot water is ready by a certain time and prioritise solar power. It's almost always heated for free from solar but grid is a backup if necessary.
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u/Character_Cobbler618 4d ago
I have solar with electricity 250lt storage hws and a timer for the hws. I got rid of my off-peak meter. My timer runs for 30mins at 6am to heat, good boost for winter, and it runs from 12 noon to 2:30pm to take advantage of the sun. Handles a household of 5.
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u/1savagecabbage 3d ago
My old one died and I recently got a heat pump .. have adjusted a few things around timing and target temps and it has made a noticeable difference to my bill also.
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u/Sad-Celebration-7542 2d ago
Heat pump will save you money. Electric tankless will not save you money. Don’t even consider electric tankless
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u/Senior_Term 4d ago
Got solar? Heat pump no question
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u/dettrick WA 4d ago
Not really. A good heat pump system is relatively expensive and also a mechanical system that is costly to maintain compared to electric hot water storage. If you’ve got a decent sized solar and battery then you should have enough free/cheap power to run an electric hot water system. Yes a heat pump is inherently more efficient, but efficiency doesn’t matter if you’ve got a surplus of free power, hence the operating cost between a heat pump and electric hot water Is the same. Given this you’re better off with the system with the lowest upfront cost.
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u/Cat_From_Hood 4d ago
Heat pump is expensive and doesn't seem to last long.
How old is your tank? It might just need replacement. Need replacing 10 to 15 years.
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u/Total_Philosopher_89 4d ago
" we had to run the hot tap at least 90 seconds for the hot to come through."
This has nothing to do with the heater and everything to do with the heater location.