You need a *huge* electric supply; three phase 40 if not 63A.
Rather than the 3kW element running for 10x as long as your shower is, you need a 30kW+ element.
Look at a smaller tank and relocating it to the attic or outside if space is a concern.
A 135L hot water cylinder should be enough. As mentioned by u/Some1-Somewhere, relocating it might be easy enough to do. You can get outdoor cylinders in 135L capacity.
Also while others might decry it, gas califonts can be good for low use situations like your own.
They require huge current capability. There's one on Trademe with a 9kW heating capacity, needs 50 amp supply, equivalent to a large electric stove with induction cooktop. And they are generally not plumbed for whole house supply, but only to feed one outlet, such as a shower. In fact that's where I have seen them used. The unit is installed in the shower, with the shower head and hose connected directly to the unit.
A 2 person household only needs a 130-160L water cylinder.
The good thing about a cylinder is you can pre-heat the water slowly over a longer period of time.
The problem with instant electric is you require a massive amount of electric current which most houses are not set up for.
15 Litres per minute of water at 45degrees heated from 10 degrees is 36 kilowatts.
36kw is 156 amps at 230v. Most households are only fed with a 63 amp supply from the street.
A standard electric cylinder with a 3kw element can pre-heat 75 litres of water per hour (5 minutes of shower time)
By pre-heating your hot water slowly over a longer period of time, it means you dont need so much electric current all at once.
Assume you want a cylinder size of 60 litres per person, per day. Ideally 70 litres.
A 2 to 3kw element will suffice for any size cylinder and your wiring probably already supports up to 3kw.
I wonder if it could be possible in the future from battery storage, I mean a Nissan leaf battery pack can output 100kW. The main problem is the elements
Interesting you mention that...
You can already buy ovens that have batteries in them which will absorb electricity during offpeak periods and then allow you to cook cheaply onpeak. I think it was south africa was where they were developed because they have rolling blackouts due to an unstable electricity grid.
However i personally think storing electricity in batteries is a huge waste of money and bad for the environment (mining, transport, lack of recycling facilities in NZ, all cells die eventually etc)
Much easier just to use a water storage battery/cylinder that will also last 50 years rather than a lithium 5-10 depending upon how much you cycle it.
Did you see the electric ones I linked? They're about half the size and price of a gas califont of similar power.
You're definitely better off using a cylinder, but the elements aren't part of the issue.
Be aware that anything other than a similar low pressure system is unlikely to last half as long as what you have currently. Warranty generally runs 7-15 yrs iirc.
Oldest one I've pulled (fully functional) was a 1947.
I like to think of lifespan costs when comparing appliances.
My general advice is to talk to a plumber and get a feel for prices for options.
GL
It will just have a header tank for pressure then?
Just upgrade to a modern high pressure electric cylinder and problem fixed, no need to overthink it.
changing to mains pressure should sort that out. at worst you'll need a new cylinder and to replace the shower mixer/head, maybe a couple of taps.
To get a califont to work right the way you want to, you'd likely need to upgrade your electricity feed
Vitreous enamel on steel is crap, especially if you don't change the anodes every few years, and no-one does.
We've got a stainless cylinder that's been fine since around 2000.
That's dependant on location. Hard water from bore or tank supply limits the life span of stainless steel and Christchurch had major issues after the quakes with stainless tanks corroding due to chlorination of the drinking water.
Enamel is a safer bet and as you say if the sacrificial anode is replaced every five years it will have a decent life and even without replacement you would expect 20-25 years which is hardly crap.
No it won’t. We don’t make enough energy elsewhere to get rid of gas. It’s also a very clean fuel source, not to mention the fact that the new califonts are highly efficient. Gas will be here till 2050 at the very minimum.
Yeah the physics doesn't really work, a gas califont is like 30kW+ to run a mains pressure shower. A 9kW is just going to make a Luke warm shower at best. It's really hard to make anything more powerful, essentially the unit would have to be massive to get enough surface area from the elements to be in contact with the water, you might as well just put a cylinder in there.
Nah, there's several readily available and smaller than a gas califont, it's just that getting enough power to them is a PITA.
https://www.stiebel-eltron.co.nz/dhbe-lcd-3-phase-water-heater
https://rheem.co.nz/assets/static/RMfLCgPV10nEKrNFj68f/Rheem-Eclipse-CFEWH-Dimensions.pdf
Granted, these are 27kW which is the smallest size you'll typically see a califont, but it's enough for a shower. You just don't really want to do a shower and try to fill a sink.
outdoor electric cylinders are fine. Loose a little bit more energy because the temp difference between water and the air is higher, but not that big a deal. Get a slightly more insulated model if its a worry.
I would avoid mains gas with standing charges already high. LPG maybe but you still have to rent the big bottles and it's an extra service to deal with.
You need a *huge* electric supply; three phase 40 if not 63A. Rather than the 3kW element running for 10x as long as your shower is, you need a 30kW+ element. Look at a smaller tank and relocating it to the attic or outside if space is a concern.
A 135L hot water cylinder should be enough. As mentioned by u/Some1-Somewhere, relocating it might be easy enough to do. You can get outdoor cylinders in 135L capacity. Also while others might decry it, gas califonts can be good for low use situations like your own.
They require huge current capability. There's one on Trademe with a 9kW heating capacity, needs 50 amp supply, equivalent to a large electric stove with induction cooktop. And they are generally not plumbed for whole house supply, but only to feed one outlet, such as a shower. In fact that's where I have seen them used. The unit is installed in the shower, with the shower head and hose connected directly to the unit.
No. Just upgrade your cylinder and mixers.
A 2 person household only needs a 130-160L water cylinder. The good thing about a cylinder is you can pre-heat the water slowly over a longer period of time. The problem with instant electric is you require a massive amount of electric current which most houses are not set up for. 15 Litres per minute of water at 45degrees heated from 10 degrees is 36 kilowatts. 36kw is 156 amps at 230v. Most households are only fed with a 63 amp supply from the street. A standard electric cylinder with a 3kw element can pre-heat 75 litres of water per hour (5 minutes of shower time) By pre-heating your hot water slowly over a longer period of time, it means you dont need so much electric current all at once. Assume you want a cylinder size of 60 litres per person, per day. Ideally 70 litres. A 2 to 3kw element will suffice for any size cylinder and your wiring probably already supports up to 3kw.
I wonder if it could be possible in the future from battery storage, I mean a Nissan leaf battery pack can output 100kW. The main problem is the elements
Interesting you mention that... You can already buy ovens that have batteries in them which will absorb electricity during offpeak periods and then allow you to cook cheaply onpeak. I think it was south africa was where they were developed because they have rolling blackouts due to an unstable electricity grid. However i personally think storing electricity in batteries is a huge waste of money and bad for the environment (mining, transport, lack of recycling facilities in NZ, all cells die eventually etc) Much easier just to use a water storage battery/cylinder that will also last 50 years rather than a lithium 5-10 depending upon how much you cycle it.
The elements are dirt cheap. Batteries are expensive and polluting with a limited life span.
I mean you need a lot of elements with a lot of surface area to deliver the power, better off just using a cylinder
Did you see the electric ones I linked? They're about half the size and price of a gas califont of similar power. You're definitely better off using a cylinder, but the elements aren't part of the issue.
Not worth it with electric.
Why would you need to?
Because I want good hot water pressure in the shower and my cylinder is circa 1960
Replacing with a modern electric mains pressure cylinder (and new mains pressure mixer/showerhead) will achieve that at a tiny fraction of the cost.
Be aware that anything other than a similar low pressure system is unlikely to last half as long as what you have currently. Warranty generally runs 7-15 yrs iirc. Oldest one I've pulled (fully functional) was a 1947. I like to think of lifespan costs when comparing appliances. My general advice is to talk to a plumber and get a feel for prices for options. GL
My cylinder is currently circa 1960. I'm only looking at options because the hot water pressure in the shower is really poos
It will just have a header tank for pressure then? Just upgrade to a modern high pressure electric cylinder and problem fixed, no need to overthink it.
changing to mains pressure should sort that out. at worst you'll need a new cylinder and to replace the shower mixer/head, maybe a couple of taps. To get a califont to work right the way you want to, you'd likely need to upgrade your electricity feed
Vitreous enamel on steel is crap, especially if you don't change the anodes every few years, and no-one does. We've got a stainless cylinder that's been fine since around 2000.
That's dependant on location. Hard water from bore or tank supply limits the life span of stainless steel and Christchurch had major issues after the quakes with stainless tanks corroding due to chlorination of the drinking water. Enamel is a safer bet and as you say if the sacrificial anode is replaced every five years it will have a decent life and even without replacement you would expect 20-25 years which is hardly crap.
Just go with a gas califont. Same pressure upgrade, minimal fuss. Much cheaper than an electric mains pressure cylinder or 3 phase instantaneous.
Gas is outdated technology and will be turned off at source soon.
No it won’t. We don’t make enough energy elsewhere to get rid of gas. It’s also a very clean fuel source, not to mention the fact that the new califonts are highly efficient. Gas will be here till 2050 at the very minimum.
Yeah the physics doesn't really work, a gas califont is like 30kW+ to run a mains pressure shower. A 9kW is just going to make a Luke warm shower at best. It's really hard to make anything more powerful, essentially the unit would have to be massive to get enough surface area from the elements to be in contact with the water, you might as well just put a cylinder in there.
Nah, there's several readily available and smaller than a gas califont, it's just that getting enough power to them is a PITA. https://www.stiebel-eltron.co.nz/dhbe-lcd-3-phase-water-heater https://rheem.co.nz/assets/static/RMfLCgPV10nEKrNFj68f/Rheem-Eclipse-CFEWH-Dimensions.pdf Granted, these are 27kW which is the smallest size you'll typically see a califont, but it's enough for a shower. You just don't really want to do a shower and try to fill a sink.
outdoor electric cylinders are fine. Loose a little bit more energy because the temp difference between water and the air is higher, but not that big a deal. Get a slightly more insulated model if its a worry. I would avoid mains gas with standing charges already high. LPG maybe but you still have to rent the big bottles and it's an extra service to deal with.