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Best and Most Cost Effective


DDD

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The cost:

Circulation pump                   R   850
15 Tube Vacuum Collector   R 6400
150L Geyser complete         R 3450  with 3Kwatt element, Water outlet, Thermostat pressure relief valve
CPU                                        R   550
200l Hot Tank                        R   220  (from Gumtree)
Piping                                     R 1980

This system uses +/- 6 units per day of which 3/4 units is generated by solar PV.  Therefore the system generates more than enough hot water for the cost of 2/3 units is via Eskom.

The hot tank is always (like in always) above 44C and the main Geyser drops as low as 32C. We use +/- 1000l of water per day (Via sea Reverse Osmosis)
From 30C to 45C takes 5 minutes and 5Watt to heat the water from 30C to 45C.
 

Any one up for a challenge to beat this?

 

image.thumb.png.fe7800a00cb326e24605feb63d36493c.png

GeaserSystem.pdf

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I am starting with a picture of what the day looks like today. No sun hardly any wind and the photo one can just see the sea +/- 200meters and normally one would have seen Table Mountain, Roben Island and the mountains all the way to Hout bay.

image.thumb.png.bdbe7dcd8ff74341e3c939c6b226c562.png

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Heatpipes have a somewhat unintuitive transfer function. The temperature range in which they work efficiently is determined by the phase change of the medium inside. Usually it is water at a lower than atmospheric pressure. Basically it means that as soon as the temperature in the heatpipe is such that there is nowhere for the water to condensate, it stops being a heatpipe and becomes a copper tube.

In some systems they utilize that characteristic to limit the maximum temperature that you can heat your water to (or more accurately, you can set a temperature - say 80°C where the heatpipe becomes much less efficient by choosing the pressures carefully.)

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When you read this remember I have my own Reverse Osmosis system.

  1. Thus  I use siphon sea water.
  2. I am grid tied so either I do  not have to pay the munic or pay them less.  ( I will not dare to say I get money back 😇)
  3. After many years my solar system burst open it was a fiber glass system.  Nr 3 that went so I installed a new normal geyser.
  4. I prefer Sushi else I like my steak rare.  😇

This is my latest graph:
14hrs.thumb.png.7ab368ed600222d6484810b560e95e1c.png

At the 1200 mark on the X axis was +/- 18H30 last night .
The different color curves are:

  • The top magenta line is the C temp of the geyser.
  • Dark blue is the temp C in the collector manifold of the vacuum tubes
  • Green is ambient temp C or temp in the shade at the collectors
  • light red/pinkish status of the circulation pump
  • Dark pink is when the element is on
  • turquoise is the temp C of the hot or holding tank.

Each mark (square block) on the X axis is 10 minutes. 

Thus 30 minutes before the 1300 mark some one went to have a bath.  At this stage the sun was setting that one can see on the collector head temp.  A few minutes later the geyser temp dropped below the holding tank and then the circulation pump got started.. The interesting fact is that a mixture of hot and cold water is now fed into the geyser. +/- 10 minutes later the holding tank C was less than the geyser so circulation was stopped.
Then because the geyser went below 50C the element was switched on and +/- 16 minutes or 800W later the element was switch off as max C was reached. 

This is the main difference between this system and others:

  1. The holding tank increased the temp fed into the geyser therefore less cold water has a lesser impact
  2. The geyser temp was increase from 48C to 52C in less than 3 minutes due to the holding tank
  3. After 16 minutes OR 800W the geyser reached 57C due to the sun and element.
  4. At this time we generated a total of 1.8Kw solar power so it cost R 0.00
  5. The remaining sun the took the geyser temp to 59.8C and the holding tank temp was 52.7C
  6. I think the switching valve is a waste.  I have it so it will stay until I get another job for it

Then interesting it was raining and cold and through the night the geyser temp dropped to 51.7C meaning any timing function was useless as the geyser element will only go on at 50C.
The hot tank dropped to 48.5C.  The ambient temp hovered at +/- 17C through the evening. This is dominantly controlled by the water mass in front of us.

At the 1900 mark the sun raised its head and winked it's eyes even it was/is totally cloudy and raining but the UV factor kicked in and immediate produced hot water. That's why the photo's. The amount of heat generated by these vacuum tubes for free is amazing. Not sure how many would have believed me but photo's don't lie.

The rest of the graph is amazing to see the rate of climb when the geyser is off the rapid increase of the temp of the collector manifold and then the geyser.

For me it is obvious that no heat pump or gas heater can produce this amount of hot water at the cost of this combination.  The combination is:

  1. Holding tank
  2. Normal geyser
  3. Circulation pump
  4. Vacuum collectors
  5. Grid tied solar.

There is just no way any system be it what ever can do the same. To be fair to all I would have never done this if there was not a debate on cost/performance/maintenance.

I will go as far to say that this is the only system that has the fastest ROI compared to any other system  INCLUDING  maintenance.

These graphs clearly shows what a "hoaks" these fancy timers are an one can do the same with a timer bought at your electrical store for 1/4 of the cost.  Sorry to say but they got you fooled.

If you use the amount of bath water we use then I can assure you that a gas geyser cost is 2 bottles of 19Kg per month.  That is crazy and almost the same cost of electricity.  Still a little bit cheaper I chuck mine at the back somewhere and now it greeting this old world due to rust. I will not mention names but I will and can not recommend any person to go the gas route unless you are oom Koos. Safe the planet by burning your gas rather than coal or nuclear.
The geewis systems is easily replaced with a timer of +/- R300 and the argument of setting temp is not that accurate. That is another crazy comment as if any person is that concerned then get VW, FIAT, Mercedes Ferrari and ... not to use any thermostats any more as you cannot trust a thermostat in your geyser so imagine how ridiculous is it to use in a car.  Does not gel.

The last one is a heat pump.  Cost wise on paper it is cheaper than gas and the conventional element.

Compare it to this type of system there is simply put no comparison.  The heat exchanger can NOT DO what this combination of products do.  Then to put it on batteries is like looking for a sober person in a British pub after Man United performance.  I do understand some people got to go that way because of a lack of infrastructure but not to to save cost nope that is a very expensive way to save cost as you will always support China

Fell free to criticize and do not be scared to blow me.  But give me facts that you can beet the system. Tant Nellie sister Stinnie's brother can not defend himself therefore facts to proof that you can beat the installation cost, the maintenance cost and running cost.

If you can beat it I will stick you for a sushi.

The following screen shot shows that the holding tank is already getting hotter due to the sun and the sun only:

Everything is free and the grid tie make sure that I DO NOT HAVE TO PAY

 

438820846_WhatsAppImage2021-11-28at13_04_31.thumb.jpeg.95f353ae5680fa055c6e29f8b899dd9e.jpeg

 

Edited by Erastus
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I could not understand what happened with my isolation and why my solar geyser burst.

image.thumb.png.ab56096a3872a3ee2a2415131885a456.png

The graph below explained the issue. The collector manifold temp at this stage was 72C.  It simply melt the isolation and the fiber glass could not stand the heat

There is no ways that you can beat a solar "vacuum tube" collector system combined with a grid tie  PV system.

Hot water is free and the beauty is one add a panel or two and then it cavers the days when temp is lows cost.

71hrs.thumb.png.1ed5c4c5eb2ab0588fa4ed5f3ba387a4.png

 

 

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8 hours ago, Erastus said:

I could not understand what happened with my isolation and why my solar geyser burst.

The sun destroys insulation over time, it becomes brittle, and turns to powder and blows away.

Motorized valves can jam or stop functioning, and if the pressure relief valve fails, this can blow the geyser.

On very hot days my water temp out the manifold, can be in the 90's. 😁

Having solar geyser and solar power is a great combination. 👍

 

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5 hours ago, TimCam said:

The sun destroys insulation over time, it becomes brittle, and turns to powder and blows away.

Motorized valves can jam or stop functioning, and if the pressure relief valve fails, this can blow the geyser.

On very hot days my water temp out the manifold, can be in the 90's. 😁

Having solar geyser and solar power is a great combination. 👍

 

That the "nice" of the holding tank. When C goes > 70  circulate between them and build up a reservoir of heat.
The reality is no need for a CPU controller a temperature switch will do the same and the switch valve is a waste.
The cost therefore can be reduced with +/- R 1100

Now this is over I will install a Real Time Clock si I can time stamp power usages and leave the geyser on as 24/7
The RTC will allow me to see daily, monthly usage in Kwhr.

GeaserSystem1.pdf

 

 

Edited by Erastus
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Two final graphs then geyser goes back on permanently.  The following graph is for two days.  On the X scale 2120 - 2900 day -1 from 2900 - 4700 Day0.

The left the collector temp went high 71C and had a small impact on the holding tank temp

day-1.thumb.png.d3c8641e00cd004c10850338af79cde2.png

The following  graph I tweaked the circulation temp  after  to lower the collector temp. This increased the water temp in the holding tank faster without dropping the C of the geyser.

3H30 both tanks C is above 42C both tanks on the roof and not properly insulated.

From 4010 the sun was setting.

 

Day0.thumb.png.09f2a3dad0827ecaf02b90bb3ef99fb3.png

Edited by Erastus
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Started of with a very cold winter day.
Ended bright sunny and warm.
Sun is setting one can see that on the collectors manifold temp

The green line in the   "center" is the ambient temp.  Today we have gusts up to 45KmHr>


The choppy  wave form is because of the gusts.  I condensed the graph the morning temp is related to rain and cloud but not so choppy.

 

image.thumb.png.f56696d0b9251740c31ddebf30692cba.png

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56 minutes ago, Erastus said:

Started of with a very cold winter day

The curse of any solar installation. 😂

What method do you use to decide when to switch the circulation pump on?

Do you use a difference (Delta) in temp between the Solar manifold temp and geyser / holding tank, or some other method?

Thanks.

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1 hour ago, TimCam said:

The curse of any solar installation. 😂

What method do you use to decide when to switch the circulation pump on?

Do you use a difference (Delta) in temp between the Solar manifold temp and geyser / holding tank, or some other method?

Thanks.

😂😂😂

The reason why I went away from batteries and grid tie.😉


Three ways maX GC -> Min GC, GThreshold, Manifold C -> MinC.  Then when GC > TC till GC == TC.
For the cold water switch when TC+2 > GC input switch to T <= GC switch back.

All variables can be modified on the fly...

A typical comms packet.
94,004,001,001,V3,V4,V5,V6,  41,50.7,50.0,43.5,17.9,00,49,45,     20,40,     20,   0,0,0,0,0,40,325a


All in all I used 9 units for the G today pushed back 65.1Kw in spite of the cold temp, cloudy weather between 8hH30 - 17H20 I heated 30 min or 1.5Kwhr.
Thus 65.1 - 9 = 56 in my favor for the day.  Still better than paying. 

If it was not for that question I would have never done this but I am pleasantly surprise the impact of the HT.

This was an interesting "experiment" and info gathering I will leave the two tanks in and add another 10 tubes.  That will do the trick for cold day then the 9 units will drop. 

With free water and free electricity I must be honest we do not worry about using hot water maybe to wasteful some times but I doubt it if the sea going to dry up in my life time or the sun stop shining.  😉

We will most definitely get heavy fines if I live else where. 
Watering my garden 20 minutes @ 400lpm, Home use 1200l per day, water my neighbors garden, neighbor get free water. 2 swimming pools and a fair size koi pond plus a 7000l koi pond at our entrance....


If it was not for RO & solar .....

Even in the drought the sea never complained.


 

Edited by Erastus
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4 hours ago, Erastus said:

Three ways maX GC -> Min GC, GThreshold, Manifold C -> MinC.  Then when GC > TC till GC == TC.
For the cold water switch when TC+2 > GC input switch to T <= GC switch back.

Ok, so you use Delta Geyser temp and Manifold temp for on, and (Delta +2 to <= GC) for off.

On my 20 tube system, I've settled on a Delta of +4 for pump on, and Delta of +2 for off.

This pushes the geyser temp up nicely throughout the day, in a step like manner without any Eskom assistance, provided the weather is not could and raining.

On a decent day the temperature is between 60C and 80C.😀

As I'm in KZN midlands, when there is rain, storms, mist, all bets are off, and Eskom assistance is required.🙄

I do not consider the geyser to be warm if its under 56C.

I am still extremely happy with my evacuated tube solar geyser, as it has given me many years of faultless service.

 

My solar PV journey is only +- six months old now, but just as fruitful and enjoyable.

Always good to have free power and hot water. :)

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3 hours ago, TimCam said:

.On my 20 tube system, I've settled on a Delta of +4 for pump on, and Delta of +2 for off.

On a decent day the temperature is between 60C and 80C.😀

I do not consider the geyser to be warm if its under 56C.

I am still extremely happy with my evacuated tube solar geyser, as it has given me many years of faultless service.

Always good to have free power and hot water. :)

Thanks for the info.  I understand your settings. I will definitely add more tubes when  I move the stuff to the area I want to have it. My 55C is easy reachable with 15 tubes.  The time to go higher is "longer" for now I settled on 55C then it warms the second tank.

The new geysers isolation is very good compared to the older one I had.  The old one was made from fiber glass.  I am back to geyser on 24/7 and the difference from off to heating to 55C and running all night is 3Kw.

Early days but with this little diffs the question is switching off and on at night worth the trouble for +/- R190 per month.  I will let it run for a few days and then check again. For now I do not recon a timer is that much saving compared to a vacuum tube system.

The more the stats compile the more the info shows timers and heat pumps is way more expensive than Vacuum tube and grid tie.

Frankly I would recon Gas, Timers and heat pumps is not in the same category at all.  They remain very expensive compared to free.

One thing for sure I remain by my statement Geepers and other timers had the owners fooled, Gas is a no go and total waste no savings COMPARED TO VACUUM TUBES.

One can argue that heat pumps have some place, Gas should stay in the bottle if you want to save.

3Kw "extra" for the night means one solar panel of 450W in a grid tie system.

What seems to be an interesting combination is the dual tank were hot water gets added to the geyser and then heated by tubes during the day.

Thus my view is your best ROI and cost effective system remains vacuum tube and the unbeatable one is vacuum tube and grid tie.

Vacuum tube and grid tie is for sure  the winners by a veerrrryyyyy long mile.

My recommendation will be stay away from timers, heat pumps, gas and batteries.  You might impress others with fancy installations which is expensive.

Nothing beats grid tie and a few small batteries for load shedding

If I read about how people struggle to maintain proper charge and cell problems and and and then good luck. My friends expensive R250K installation from a very well known brand has battery issues and crazy enough they still pay monthly electricity.  My basic grid tie for R56K odd I am smiling all the way.

I had batteries, timers gas stand alone system. backups

I tried the rest now I have the best grid tie money back free water free electricity.  Nothing beats money back. Unless you had a luck of buying at the right time else I have never heard of buying something for +/- R56 000 and then get money back at +/- R6K per month tax free. It is unbeatable

Who can beat that with batteries, expensive systems, heat pumps and timers.

And then don;t forget:

Watering my garden 20 minutes @ 400lpm per day, Home use 1200l per day, water my neighbors garden, neighbor home get free water. Running 2 swimming pools and a fair size koi pond ( >55000l).

 

Edited by Erastus
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On 2021/12/03 at 1:20 AM, TimCam said:

Ok, so you use Delta Geyser temp and Manifold temp for on, and (Delta +2 to <= GC) for off.

On my 20 tube system, I've settled on a Delta of +4 for pump on, and Delta of +2 for off.

 

On a decent day the temperature is between 60C and 80C.😀

 

If I may,

When you reach the delta and you circulation pump goes on do you know what C is your geyser?

The past three day an interesting scenario is happening.  If you look at the graph below the C of the manifold reaches 70 plus no problem.

The magenta and cyon lines  is the hot tank and geyser temp.  In this scenario the inlet and outlets are the same C and the tanks both are the same C and circulation.  The natural convection is in this case not "good enough" to transfer the temp from the manifold to the geyser.

My old geyser the tubes went into the geyser which seems to be better but more difficult to add more tubes.  One thing for sure the geyser etc. does not reach max temperature in this case

DayLimit.thumb.png.9eb9f6aece079b2b8b1caa99568300f1.png

So here we go I have ordered me this little motor 12V 18W and 800lph.  Maybe some has the same situation without realizing it.  This definitely has an impact on the temperature of both tanks and the manifold..  Recon in short its always better to have a very small circulation to help mother nature.

The pumps cost delivered is +/-R400

 

d78d17b4-e6b1-451b-b691-7d32bc57312f.JPG

Edited by Erastus
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On 2021/12/05 at 10:39 AM, Erastus said:

When you reach the delta and you circulation pump goes on do you know what C is your geyser?

Yes, the delta (difference) is between the Solar Manifold water temperature, and the Geyser water temperature. The On delta is actually 6 deg. and Off delta is 2 deg.

It has been so long since I changed anything, that's why I thought it was 4 deg.😂

So when the Solar Manifold water temperature is 6 degrees Higher than the Geyser water temperature, the circulation pump is switched on. I must use a pump, as the Geyser is below the Solar Manifold and tubes. Once the pump starts, the water temperature in the Solar Manifold increases quite a bit. When the Solar Manifold water temperature reaches 2 degrees or lower than the Geyser water temperature, the pump is switched off. The temperature measurements are all instantaneous, and dynamically compared for control purposes.

I also have other features in the controller, including de-Icing, pump restarting (if jammed), element control, etc.

Set points and other adjustments are updated with a PS2 type thumb joy-stick.

I enjoy messing around with such projects, but unfortunately time is short now days.

Some Pictures of different configs and displays. 👍

 

Geyser_Main.jpg

Geyser_Joy.jpg

Geyser_Config1.jpg

Geyser_Config2.jpg

Geyser_Config3.jpg

Geyser_Set_Val.jpg

Geyser_Vars.jpg

Geyser_Vars1.jpg

Geyser_De-Ice.jpg

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