water heaters and inverters

[PatrickV]

Hi, I'm a new member. Came across this forum by chance and it seems to be a very interesting forum indeed. I own a small holiday flat in a building that has a 3 phase Stiebel Eltron instant hot water heater. Works well enough. Except during load shedding. My guests complain about not being able to shower when there's load shedding. I'm thinking about installing an 8kwh inverter/battery system and replacing the Stiebel Eltron heater with an Ariston 30L oversink heater (single phase and 1500w consumption). I'm not at all technically minded – this has been suggested to me – but I'd like to hear from anyone with experience and/or expertise. Would appreciate any constructive input. Patrick

[Justloadit]

Consider a locally manufactured solar geyser controller - Geyserwatcher, with mains as a back up if required for days with no sun or over consumption of hot water.
249634 GW A5 DS LEAFLET PN258450(d1).pdf
Geyserwatcher prices.pdf

[Derlyn]

I feel I am well qualified to respond, having used an electric showerhead for the last 8 years.

The solution offered by Justloadit is a good one if the budget allows for it.

The savings that we experience by using the showerhead ( mine is 5Kw ) is sufficient for us to work around the fact that we cannot have a hot shower during loadshedding.
In summer I shower cold ( many health advantages ) and in winter I just reschedule my showering time.

The showerhead's monthly cost for 10 minutes of shower time per day ( 2 people, 5 minutes each ) is R86.
If we used an electric geyser for 2hrs each day it would be R619.
A gas geyser used also for 10 minutes per day will cost R232.

If you are thinking of installing an inverter for loadshedding purposes, my recommendation ( the cheapest solution for immediate installation ) is to install a gas geyser.
They are perfect for showering, but will not work for a bath.

I now sit with the same predicament.
Thinking of installing an inverter for loadshedding.
My monthly usage is +- 150 units (R500) That is low compared to most average households.
I could get away easily with a 3Kw inverter, but I'll still have to work around the showering story because of the 5Kw showerhead.

In my case, if I wan't to have a guaranteed hot shower during a stint of loadshedding, it's either a gas geyser or an 8Kw inverter setup.
A donkey, or rocket geyser in the backyard will also work.
An electric geyser is not an option for me.

We do not have hot water in the kitchen. The most economical way of washing dishes is to boil a kettle of water, pour it into the sink, add a bit of cold water and wash the dishes. Sorted.


We have decided on a 3Kw inverter and work around showering times as we have been doing up to now.

[Die sparky]

Would you use like a pull cord isolator for the electric shower head?

[Derlyn]

Nope. There is an isolator like all fixed appliances must have, but this isolator doesn't control the unit.

It has an internal diaphragm that activates a switch as soon as water flows through the unit. The slower the water flow, the hotter the water. When water stops flowing the unit automatically switches off.

Simple but effective.

[Derlyn]

Google Lorinzetti.

[Die sparky]

Oh ok cool so you use a normal wheatherproof isolator? I see overseas they use a pullcord type. Mind posting a pic of the install?

[Die sparky]

Also since one can use regulations that was valid at the time of a installion where can one find regulations from 1922 this all seems so complicated

[GCE]

An electric geyser is not an option for me.

We do not have hot water in the kitchen. The most economical way of washing dishes is to boil a kettle of water, pour it into the sink, add a bit of cold water and wash the dishes. Sorted.


We have decided on a 3Kw inverter and work around showering times as we have been doing up to now.

Why is a normal electrical geyser not an option - The advantage is that the hot water is stored and can be used during loadshedding
If I was you I would not go less than 5kw inverter - the price difference is not big but it allows the odd spike .Also with ongoing water problems you could at least then run a small pump

Use a true hybrid that can feed back onto your house grid and have the geyser on the house grid with a timer - I heat the geyser between 11H00 and 14H00 to utilize the PV and a 150L geyser gets us 4 showers without having to heat outside of sun light hours - Geyser effectively cost me nothing - I have 2 geysers , one for the flat that presently has a short term tenant

I have a 5kw inverter , 5kwh battery and 5.1kw panels - generally use around 22Kwh per day but only have to purchase 5kwh per day.

I vary my usage depending on PV output with the pool pump .

You would not need to fit 5kw of panels but could start with 1 mppt with 3 Kw of panels and if needed at a later stage you could expand.

We have started numerous people off on 5Kw inverter and 3 Kw of panels - 2 of them have now expanded the systems to take extra panels and batteries to run the majority of time " off grid"

[Derlyn]

Why is a normal electrical geyser not an option - The advantage is that the hot water is stored and can be used during loadshedding

For me it boils down to rands and cents, not paying to heat a drop more water than what we need.

I suppose a solar geyser would work ( the sun is free at the moment, don't know for how much longer ) but it would have to be the budget type without an element. During bad solar periods, we can use our electric showerhead. That is if we've got electricity

That way, I can further reduce the R86 monthly that we presently spend on water heating and a bonus will be hot water in the kitchen sink.

With our water tanks, we only use some Municipal water for about 3 months of the year during the dry season. By adding another 2 tanks, we will be able to go without Munic water completely. The problem is space for the tanks. Small erf.

[PatrickV]

water heaters and inverters

Consider a locally manufactured solar geyser controller - Geyserwatcher, with mains as a back up if required for days with no sun or over consumption of hot water.
[ATTACH]8904[/ATTACH]
[ATTACH]8905[/ATTACH]

Thank you for your input, but I think some people have missed the point. I am not dealing with solar backup - it's not an option in our block of flats. I'm merely adding an inverter/battery system that will power some things (including the 30L Ariston over-sink water heater) during load shedding. I just want to know if the 8kw system will be able to power the Ariston?

[Isetech]

An 8 kw inverter would be able to supply power to a 1,5 KW resistive load. A 5 kw inverter would do the job. the battery will determine if it will last for the 2 hours load shedding.

Just a note, take note of the capacity of the battery and the C rating.

It is advisable to go at least 2 x 5 kwh or 1 x 10 kwh minimum for an 8 kw inverter. If for some reason you do only go with 1 x 5 kwh battery, you might need to get the installer to do a few calculations.

The C rating will determine the charge and discharge rate, which shouldn't be a problem if you use a decent battery brand, which would be rated at least C0.5.

Thank you for your input, but I think some people have missed the point. I am not dealing with solar backup - it's not an option in our block of flats. I'm merely adding an inverter/battery system that will power some things (including the 30L Ariston over-sink water heater) during load shedding. I just want to know if the 8kw system will be able to power the Ariston?

[Isetech]

By the way, I wish you luck with installing a battery system in a block of flats, especially if it is a lithium battery.

You will need to speak to your body corporate, your insurance company and make sure it covers your flat and every part of the building it might burn, if that battery catches on fire for any reason, be it loose connections or because of an external fire, you could be liable for the damages for everything.

I am busy with an installation in a complex and boy am I glad I didn't just slap the system on the wall and issue a COC.

I am not a ware of any lithium battery brand that is suitable for installation inside a building, especially a block of flats.