Continuous Electric Hot Water Heaters

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#3295573 10-Oct-2024 15:09

for a bach, gas califont. 2x9kg gas bottles.

the problem with electric continuous is they draw large amounts of current. probably 30-40 amps which is probably 50-75% of what your whole house can have.

SomeoneSomewhere

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#3295575 10-Oct-2024 15:16

Regarding 4, old shouldn't matter. The element either works or it doesn't; there is very little in between. Leaking heat/water will slightly increase power requirements but not even close to the recovery rate.

It's likely you only have a 3kW element; this is standard and most properties don't have provision for a two-element cylinder. Many of the two-element cylinders listed are non-simultaneous for time shifting; you run the top element during the day so some hot water is available, then you refill the whole tank overnight.

For ripple, you should be able to find out either from your power bill or the ICP Checker. If you are only charged for uncontrolled power (UC, UC-24, 7304) then there is no ripple. If there is any controlled or inclusive (CN, AI) then you've got ripple. Beware that the databases used for billing and the ICP lookup aren't always 100% accurate.

Stainless cylinders last way longer than vitreous enamel. Regular anode replacement is essential for vitreous enamel cylinders, and no-one ever bothers.

SomeoneSomewhere

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#3295576 10-Oct-2024 15:18

tweake:

for a bach, gas califont. 2x9kg gas bottles.

the problem with electric continuous is they draw large amounts of current. probably 30-40 amps which is probably 50-75% of what your whole house can have.

Try 30-40A three phase.

dimsim

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#3295577 10-Oct-2024 15:19

Looking at our energy usage via Mercury, are these 5 hourly spikes likely to be the hot water cylinder meaning there is no ripple control?

Jase2985

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#3295654 10-Oct-2024 16:32

i would say so, our 180L cylinder is about every 7 hours but its only about 10 years old. Tops up for about 15 minutes.

SomeoneSomewhere

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#3295663 10-Oct-2024 16:53

Likely HWC, yes.

Doesn't necessarily mean no ripple control though it does mean it's not off all day. Some lines companies (e.g. Orion) only use ripple control when necessary and never in the summer. Typically, they won't turn the cylinder off for more than 4-6 hours anyway.

Ideally you would look at it during a day/week when guests were present and complained of low hot water.

RunningMan

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#3295672 10-Oct-2024 18:14

dimsim: wife has deemed it necessary to remove all flow restrictors at the bach.

This is likely a big contribution to the issue then. Reducing the water used will help if you can.

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cshwone

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#3295675 10-Oct-2024 18:49

If you go for a gas based solution, which I would recommend as you would be unlikely to ever run out of hot water, - given your use case with guests, I would recommend twin 45kg bottles. More economical than 9kg and your property manager can monitor and order a replacement when required.

WWHB

35 posts

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#3295678 10-Oct-2024 18:59

Please don’t listen to those saying to run a gas hot water system on 9Kg bottles. This is not correct, a 9 Kg bottle can supply a max of 19mJ/hour and a 26 unit like a Rinnai Infinity or Rheem Integrity draw 199mJ/hour. The gas n 9Kg bottles is usually dirty as well and if any of this gets sucked through into your unit it will invalidate the warranty and is not compliant. Gasfitters who install systems on to 9 kg bottles are not complying with the gas regulations in NZ.

look at getting a Hot Water Heat Pump with wifi control. You could turn it on the day before someone arrives and systems like the Reclaim have faster recovery than an element. This option will be expensive compared to other systems

nickb800

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#3295689 10-Oct-2024 19:50

WWHB:
Please don’t listen to those saying to run a gas hot water system on 9Kg bottles. This is not correct, a 9 Kg bottle can supply a max of 19mJ/hour and a 26 unit like a Rinnai Infinity or Rheem Integrity draw 199mJ/hour. The gas n 9Kg bottles is usually dirty as well and if any of this gets sucked through into your unit it will invalidate the warranty and is not compliant. Gasfitters who install systems on to 9 kg bottles are not complying with the gas regulations in NZ.

look at getting a Hot Water Heat Pump with wifi control. You could turn it on the day before someone arrives and systems like the Reclaim have faster recovery than an element. This option will be expensive compared to other systems

Why would you put a hot water heat pump in a bach? With so little hot water use you'd never come close to recouping the additional cost for a heat pump, over and above a basic electric resistive heating cylinder

WWHB

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#3295728 10-Oct-2024 21:10

nickb800:
WWHB:

Please don’t listen to those saying to run a gas hot water system on 9Kg bottles. This is not correct, a 9 Kg bottle can supply a max of 19mJ/hour and a 26 unit like a Rinnai Infinity or Rheem Integrity draw 199mJ/hour. The gas n 9Kg bottles is usually dirty as well and if any of this gets sucked through into your unit it will invalidate the warranty and is not compliant. Gasfitters who install systems on to 9 kg bottles are not complying with the gas regulations in NZ.

look at getting a Hot Water Heat Pump with wifi control. You could turn it on the day before someone arrives and systems like the Reclaim have faster recovery than an element. This option will be expensive compared to other systems

Why would you put a hot water heat pump in a bach? With so little hot water use you'd never come close to recouping the additional cost for a heat pump, over and above a basic electric resistive heating cylinder

I did say it would be expensive.

Maybe there is some sort of wifi control you can use with a standard Hot Water Cylinder. They are also using a lot of hot water, over 300 litres. That’s the only reason I mentioned the Reclaim system, that system uses a 300 litre cylinder and if you run out it has a 20 minute recovery for another shower. ( also a much more environmentally friendly option and should add valve to the property)Gas would give endless hot water as long as he has gas, just don’t with the 9 Kg advice.

SomeoneSomewhere

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#3295733 10-Oct-2024 21:21

Setting up remote control of a HWC is easy enough; add a contactor and use any WiFi switch/relay.

That reclaim system is only a 4.7kW capacity at a very optimistic 19C outdoor temperature. Expect that capacity to crater at low outdoor temperatures, especially near/below freezing.

SomeoneSomewhere

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#3295735 10-Oct-2024 21:32

It looks like almost all cylinders here use a 1 1/4" BSP fitting for the element. Assuming the cylinder is of sufficient diameter, there's no reason you couldn't add a circuit and replace the thermostat to fit a 6kW element like this: https://smithsnz.co.nz/collections/tank-elements/products/6kw-low-watt-density-element-450mm-long

Pretty much all tanks have a TPR valve good for 10kW.

More hot water capacity is really ambulance at the bottom of the cliff, though. Fix whatever is letting people empty a 300L tank, unless this is being used as something like a ski bunkhouse with two dozen people turning up for a hot shower and to crash for the night.

dimsim

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#3295748 10-Oct-2024 22:07

RunningMan:

dimsim: wife has deemed it necessary to remove all flow restrictors at the bach.

This is likely a big contribution to the issue then. Reducing the water used will help if you can.

haha, do you have a wife?

dimsim

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#3295749 10-Oct-2024 22:08

cshwone:

If you go for a gas based solution, which I would recommend as you would be unlikely to ever run out of hot water, - given your use case with guests, I would recommend twin 45kg bottles. More economical than 9kg and your property manager can monitor and order a replacement when required.

100%, we have these at home already, which is why I thought it could be a solution.

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