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Energy efficient 150L Geyser retrofit solutions


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Hey Guys

 

My ultimate goal is off grid- however I am doing this in bite sized pieces.

I am looking to tackle my geyser 1st however a few questions:

We have a smart geyser that allows me to set the max temp and track usage etc.

Question 1

- We average around R850 per month based on the app, however my full pre paid spend is never less than R2500/ month in Summer and+/- R5500/ in Winter.

- If the geyser is meant to be my largest entry spend monthly why is it so low relative to my boll?

- I'm assuming the scaling on the app uses uses a unit cost that is wrong (I cant change this)

- Does an average 545kWh usage make sense?

image.thumb.png.437960a0adff98d152997dd8eed4f9fc.png

 

Question 2

If my numbers are correct- what benefit could I get from alternate geyser strategies

Question 3

Solar vs Heat Pump vs Other ???

- What do I look and consider?

 

Tx

 

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Hi,

Q1 - your scaling may be wrong, but the numbers are way off. Either you are not measuring at the correct point (incoming from grid) or maybe you have a faulty meter or something else after the prepaid meter that is using electricity that you are not aware of. For R2500/month is over 1000kWh and R5500/month is over 2200kWh

Q2 - your standard 3kW geyser will on average use about 400 kWh per month (in winter even more). Installing a heat pump or solar geyser will reduce this to about 1/3 of your current consumption.

Q3 - both are good option and difficult to choose between them. Best would be to analyze your geyser alone usage and do the calculations based on expected savings and payback time.

 

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Hi Ryan,

Seems your geyser consumes around 20kWh's per day - which is fairly high for a single geyser. Does your smart geyser not allow you to set schedules?

You could recalculate your monthly cost for the geyser if you know your pre-paid rates, its definitely higher than what your app reports.

I was using around the same daily power for 1x200l and 1x150l geysers running 24x7. I've installed CBI Astute smart timers and I now average around 10kWh per day. There are also numerous posts on the forum where guys have managed to use traditional timers or sonoff's and relays to achieve the same outcome.

 

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I'm still busy with my off grid solution, and it seems like it will be a long journey.

 

1. Regarding your weird power consumption, I am struggling with my consumption values as well. According to the Tshwane meter, we have used 390 units this month which seems excessive considering most of the day we get free power from the sun. Tshwane says 390 units (a massive improvement over 1200 units every month), and my Sunsynk says 260 kWh. Do I believe Tshwane, the Sunsynk or take the middle road? Good luck, I am still hunting.

 

2. We have an electric geyser in the Cottage. It also used a ton of power and killed SOC before the last of the daylight was even gone. I put it on a CBI Astute on the recommendation of a number of threads here, and now the daily usage is only during the day, and the current usage averages 4 kWh per day. It is on in the morning for an hour from 08h30 (just enough time for the SOC to absorb a little bit of the load with the solar) and again a bit later in the afternoon. It powers down from 16h00. In winter I might make this a little bit earlier.

 

3. In my very limited experience, I think solar geyser is a bad idea. If your solar panels don't produce enough electricity your solar geyser likely wont either. So if I want to go solar geyser, the solar will come from the electric solar panels. However, considering the savings with the normal electric geyser I would like to add a heat pump. That should drop the consumption by a factor 3 - 4. I'll be watching this thread for some more ideas too.

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11 minutes ago, Paul Greeff said:

3. In my very limited experience, I think solar geyser is a bad idea. If your solar panels don't produce enough electricity your solar geyser likely wont either. So if I want to go solar geyser, the solar will come from the electric solar panels. However, considering the savings with the normal electric geyser I would like to add a heat pump. That should drop the consumption by a factor 3 - 4. I'll be watching this thread for some more ideas too.

I'm not sure what you mean by 'solar geyser'. If you are supplying the geyser with excess inverter power courtesy of the nuclear fission fireball in the sky then that's fine. The difficulty is to determine if there's excess solar power available..

Heaven forbid you are heating your geyser from your batteries!

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36 minutes ago, Richard Mackay said:

Heaven forbid you are heating your geyser from your batteries!

Goodness me, no. I saw the devastating effects on day one. The sun had barely started to set when the electric geyser and stove combined forces and put me and my batteries in their place. The geyser got the CBI Astute wifi timer, and the electric stove is now gathering dust under a carport while my folks cook in luxury on a fancy gas stove.

I consider the timer on the geyser as one of the cheapest wins resulting in massive savings we have made in this solar journey.

 

Solar vs Heat Pump vs Other ???

I incorrectly interpreted this as the alternative to powering the electric geyser from solar power, so solar water heater, the evacuated tube kind was what I thought, my bad. 

 

36 minutes ago, Richard Mackay said:

The difficulty is to determine if there's excess solar power available.

I'm also interested in this. 

I have requested an API key from Solarman but I haven't gotten around to see what their API will offer. I am hoping for the SOC. This and time of day should be sufficient to make a decision on when to power the geyser.

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I tend to think that changing the habits should happen before you venture into solar. There are many ways that we all know about how to reduce your consumption. There is also a change that could be done in terms of using energy during the day, but is it really necessary to go backwards?

what is the point of switching off the geyser at 4pm and end up with cold showers? If you lived like that before, why change after solar? Also, now you can’t have a geyser and a kettle on at the same time, and you have to watch your battery go down. 

Renewable power has it’s limitations but it shouldn’t be total inconvenience.

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Maybe start from the ground up and check how much hot water your household actually consumes and when. Everytime you empty the geyser and heat the incoming cold water to temperature, say a 3kW element running for 1.5 hrs, that's 4.5kWh. If you for argument's sake run two or three large hot baths baths in the evening and maybe a handful of 15-minute showers in the morning, and add in 2kWh for standing losses (heat radiated to the atmosphere - better geyser insulation like a geyser blanket can help you only so much), that's quite plausibly approaching 18kWh average per day. With that theoretical pattern of consumption a solar geyser might not help you, it'll maybe provide one hot bath at the end of the day. In that scenario I would rather investigate a heat pump. Unless your estimated usage is nowhere near that much, in which case your problem lies elsewhere.

Edited by GreenFields
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3 minutes ago, GreenFields said:

Maybe start from the ground up and check how much hot water your household actually consumes and when. Everytime you empty the geyser and heat the incoming cold water to temperature, say a 3kW element running for 1.5 hrs, that's 4.5kWh. If you for argument's sake run two or three large hot baths baths in the evening and maybe a handful of 15-minute showers in the morning, and add in 2kWh for standing losses (heat radiated to the atmosphere - better geyser insulation like a geyser blank can help you only so much), that's quite plausibly approaching 18kWh average per day. With that theoretical pattern of consumption a solar geyser might not help you, it'll maybe provide one hot bath at the end of the day. In that scenario I would rather investigate a heat pump. Unless your estimated usage is nowhere near that much, in which case your problem lies elsewhere.

Yes, it's a good idea to get to grips with your geyser electricity usage (or any electricity usage for that matter)

I installed a kWh meter dedicated to the geyser so I could actually keep track. I have installed a geyser solar blanket and reduced the thermostat to 'just hot enough'. I manage the geyser like one uses a kettle: Only switch it on when you need to shower/whatever. (It's a 3 kW element so it heats the 200l geyser in under 30min)

By doing this our house (2 people) use less than 5 units per day.

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On 2021/02/24 at 2:00 PM, RyanBM said:

Hey Guys

 

My ultimate goal is off grid- however I am doing this in bite sized pieces.

I am looking to tackle my geyser 1st however a few questions:

We have a smart geyser that allows me to set the max temp and track usage etc.

Question 1

- We average around R850 per month based on the app, however my full pre paid spend is never less than R2500/ month in Summer and+/- R5500/ in Winter.

- If the geyser is meant to be my largest entry spend monthly why is it so low relative to my boll?

- I'm assuming the scaling on the app uses uses a unit cost that is wrong (I cant change this)

- Does an average 545kWh usage make sense?

image.thumb.png.437960a0adff98d152997dd8eed4f9fc.png

 

Question 2

If my numbers are correct- what benefit could I get from alternate geyser strategies

Question 3

Solar vs Heat Pump vs Other ???

- What do I look and consider?

 

Tx

 

How is this app set up? It can't know about cost, it knows about consumption. So there will be a parameter to see a kw/h costs X and the app/device will do a simple calculation. Also the tariff your municipality applies will escalate. IE for me the first 350 kw/h a month are the cheapest. Then for 351 to 500 I pay more and so on. The app probably isn't taking that into account either.

And then there may be other fees like we have in Johannesburg where post-paying customers get hit with one flat fee for provision of a connection, a second for managing your account, plus a "demand management" fee that seems to vary with consumption. 

So look at kw/h for the geyser as a %age of the total kw/h used.

I second what Richard and Brani say above. Getting to grips with how much power you use and when you use it is a good exercise, and if you start adding in some controls and a bit of discipline then you can save some money without spending. You will read over and over again on this forum that if you are going to maximise the benefits of [whatever it is] then you have to modify your own behaviour a bit. 
 

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Tx for the feedback guys.

Here is some further info:

- I actually have 2 x 150L geysers however to mu knowledge only one is powered

- The geyser has a senesable monitor fitted to it- its' primary purpose is leak detection.

- The app only has 2 settings- Set Temp, Set on/off times.

- I have pulled the data over the last year which shows an average usage of 557kWh per month.

image.thumb.png.4339e1c0140f631019b459bc7cecfe30.png

 

- The geyser is set to run continuous 

- The reason I have not set on/ off times, is I've read that it takes the same amount of energy to keep it hot over a period vs having it heat it from scratch at times

 

Next question:

- We are a small family of 4 wife and 2 kids

- Our hot water needs are: showers between 5am to 7am and again 4pm to 7pm and hot water to wash dishes

- Should I adjust the on/off times and if so is 60mins sufficient to heat the water again?

 

Tx

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On 2021/02/24 at 2:22 PM, Brani said:

Hi,

Q1 - your scaling may be wrong, but the numbers are way off. Either you are not measuring at the correct point (incoming from grid) or maybe you have a faulty meter or something else after the prepaid meter that is using electricity that you are not aware of. For R2500/month is over 1000kWh and R5500/month is over 2200kWh

 

 

I'm not following this statement- are you saying my consumption as a whole makes no sense as it is too high or too low?

We were on post paid and have seen a +/-10% cost reduction since going prepaid

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On 2021/02/24 at 3:30 PM, branderplank said:

Does the graph only represent the use of your geyser and no other circuits? At what point are you measuring the use?

What did you use to measure this and get this information?

Agree that the rand values do not look right

This is just the geyser- with the sensor on the actual geyser- it comes to the senseable app.

https://play.google.com/store/apps/details?id=com.sensornetworks.Nedbank&hl=en_ZA&gl=US

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On 2021/02/24 at 3:32 PM, Desh said:

Hi Ryan,

Seems your geyser consumes around 20kWh's per day - which is fairly high for a single geyser. Does your smart geyser not allow you to set schedules?

You could recalculate your monthly cost for the geyser if you know your pre-paid rates, its definitely higher than what your app reports.

I was using around the same daily power for 1x200l and 1x150l geysers running 24x7. I've installed CBI Astute smart timers and I now average around 10kWh per day. There are also numerous posts on the forum where guys have managed to use traditional timers or sonoff's and relays to achieve the same outcome.

 

As I relayed above- I actually have 2x 150L geysers- but to my knowledge only one is power.

This app does allow me to set on/off times and max temps

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7 minutes ago, RyanBM said:

I have pulled the data over the last year which shows an average usage of 557kWh per month.

Ok, I am sorry I misunderstood your original statement. You have already analyzed your geyser usage. If only one is powered, that is pretty high usage.

You can expect to drop that to about 100-150kWh (roughly) with heat pump.

 

What is your temperature settings? My heat pump is set to 55 degrees, and it's pretty good for the same size family 

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5 minutes ago, Brani said:

Ok, I am sorry I misunderstood your original statement. You have already analyzed your geyser usage. If only one is powered, that is pretty high usage.

You can expect to drop that to about 100-150kWh (roughly) with heat pump.

 

What is your temperature settings? My heat pump is set to 55 degrees, and it's pretty good for the same size family 

Tx Brani. 

 

Max is at 55deg.

The breaker on geyser 2 is off. 

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19 hours ago, Speedster said:

Evacuated tubes are really cheap nowadays. Best, and easiest, retrofit option

I agree

Typically the prices are around R15000 for the 200L and R13000 for the 150L

I had an evacuated system in my house and my electricity went from 14 KWH to 7 KWH per day

(Edited by Moderator)

Edited by Moderator
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2 hours ago, Clint said:

I agree

Typically the prices are around R15000 for the 200L and R13000 for the 150L

I had an evacuated system in my house and my electricity went from 14 KWH to 7 KWH per day

(Edited by Moderator)

You should be paying about half that. 

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@RyanBM seems ok, I have issues with the quote, though... pump - OK, panel - OK, battery - hmmm unless there's ancillary electronics, which is not mentioned that will keep voltage etc. in check and pump off, once the panel doesn't produce, I suspect this battery will be dead 12months down the drag, it may be betterer to do the pumping off mains + 12V PSU, based on sunshine or a temperature sensor to check whether warm water can be moved about, rather and forget about the 10W panel and battery instead, since this, I would imaging will be more of a headache than a reliable way of automating things.

As for the costing being reasonable or not, I think its probably not too excessive, but what do I know, I couldn't afford it right now 🙂

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