Vacuum tube solar Geyser

qscwbt

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So I did a lot of research regarding solar geysers with the current and expected increases from E-scum. Would prefer to contribute less to ceo bonuses.
I did a lot of reading and decided on the following system. I decided to share my experience as this might help someone else. They system depends on location, family size, personal requirements. Thus a very custom type solution.

We a family of 3 and used a 150 litre kwikot geyser that is about 1 year old.

I decided to do a hybrid system.
I fitted 24 evacuated tube 200 litre Solar Ray geyser. This is fitted outside on the roof. On the solar Geyser I asked them not fit any element and use this purely as a solar geyser. The solar Geyser is then plumbed to feed hot water to the normal electric 150 litre kwikot geyser (in roof). The kwikot geyser is now connected to the geyser wise controller. The controller is set to switch on between 16h00 and 18h00 if the temp is below 55 degrees on weekdays. On weekends it will check if temp is below 55 degrees between 4 and 6 am and 16h00 and 18h00 and only heat the water in that time period if required.

In the evening the kwikot geyser is sitting at +-58 degrees. So the element does not need to go on. As everyone now bath or shower the water in the kwikot is now replaced with hot water from the solar geyser, by the time everyone is finished the temp in the kwikot sits at 63 degrees. During the night the kwikot will loose 2-3 degrees of heat. So by morning the temp will be sitting at +- 60 degrees.
During the day I would lose another 2-3 degrees. So by the time everyone needs to shower / bath again the geyser temp is at 57 degrees.

So we at a point where the geyser is not switching on at all. We do not run out of hot water, and we did not have to change our lifestyle.
For the last 9 days the system had to use the element for only 2 hours. 2 hours in 9 days is not bad considering the average geyser runs +- 4.6 hours a day.
 

jem

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If you don't mind spilling the beans, what did that setup cost you? My geyser is killing my electricity account...
 

qscwbt

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Jem

it was R23k.
I got a 10 year warrantee, and there is no services or maintenance on the system.
 

thehuman

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So I did a lot of research regarding solar geysers with the current and expected increases from E-scum. Would prefer to contribute less to ceo bonuses.
I did a lot of reading and decided on the following system. I decided to share my experience as this might help someone else. They system depends on location, family size, personal requirements. Thus a very custom type solution.

We a family of 3 and used a 150 litre kwikot geyser that is about 1 year old.

I decided to do a hybrid system.
I fitted 24 evacuated tube 200 litre Solar Ray geyser. This is fitted outside on the roof. On the solar Geyser I asked them not fit any element and use this purely as a solar geyser. The solar Geyser is then plumbed to feed hot water to the normal electric 150 litre kwikot geyser (in roof). The kwikot geyser is now connected to the geyser wise controller. The controller is set to switch on between 16h00 and 18h00 if the temp is below 55 degrees on weekdays. On weekends it will check if temp is below 55 degrees between 4 and 6 am and 16h00 and 18h00 and only heat the water in that time period if required.

In the evening the kwikot geyser is sitting at +-58 degrees. So the element does not need to go on. As everyone now bath or shower the water in the kwikot is now replaced with hot water from the solar geyser, by the time everyone is finished the temp in the kwikot sits at 63 degrees. During the night the kwikot will loose 2-3 degrees of heat. So by morning the temp will be sitting at +- 60 degrees.
During the day I would lose another 2-3 degrees. So by the time everyone needs to shower / bath again the geyser temp is at 57 degrees.

So we at a point where the geyser is not switching on at all. We do not run out of hot water, and we did not have to change our lifestyle.
For the last 9 days the system had to use the element for only 2 hours. 2 hours in 9 days is not bad considering the average geyser runs +- 4.6 hours a day.
Summer time you should easily ne able to save 95% on hot water bill
Winter time im guess save about 50%.

Our system maxed out a few days ago on 87 degrees
 

X-Gamer

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I'm assuming these sorts of systems have a way to bypass the solar tubes when temperatures, for example, get to 87C on a very hot day?

Otherwise, you may end up damaging the system, or worse, getting someone injured.
 
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Geoff.D

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Interesting idea, thanks for the info.

Why did you opt for the external storage geyser and not use the existing geyser to store the solar heated water? Or is the external tank a requirement for use with the system. Effectively, you now have 350 litres of hot water available for a family of three.
 
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qscwbt

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I'm assuming these sorts of systems have a way to bypass the solar tubes when temperatures, for example, get to 87C on a very hot day?

Otherwise, you may end up damaging the system, or worse, getting someone injured.


The system has a pressure release if it gets to hot. this gets replaced with cold water.
 

qscwbt

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Interesting idea, thanks for the info.

Why did you opt for the external storage geyser and not use the existing geyser to store the solar heated water? Or is the external tank a requirement for use with the system. Effectively, you now have 359 litres of hot water available for a family of three.

Hi Daniell

Well I chose this for a following reasons:
1. Everyone advised that you need +- 70 litres of hot water per person a day on average. Thus for a family of 3 I need 210 litre. with solar its better to go bigger.
2. I looked at the vacuum tubes only to feed the current geyser. (cheaper option) but if you have a 150 l geyser and its nice and hot. Now wife bath the kids and do some dishes. now you taking out say 70 litre of hot water. this is now replaced with 70 litre of cold water. Now you cooling the water that was still in the geyser. so the element needs to warm it wasting enegry

On the system I have now if someone uses hot water I am adding (sun depending) hotter water from the solar to the kwikot. Thus the water stays warm and the geyser has no need to switch on.
 

Geoff.D

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Hi Daniell

Well I chose this for a following reasons:
1. Everyone advised that you need +- 70 litres of hot water per person a day on average. Thus for a family of 3 I need 210 litre. with solar its better to go bigger.
2. I looked at the vacuum tubes only to feed the current geyser. (cheaper option) but if you have a 150 l geyser and its nice and hot. Now wife bath the kids and do some dishes. now you taking out say 70 litre of hot water. this is now replaced with 70 litre of cold water. Now you cooling the water that was still in the geyser. so the element needs to warm it wasting enegry

On the system I have now if someone uses hot water I am adding (sun depending) hotter water from the solar to the kwikot. Thus the water stays warm and the geyser has no need to switch on.

Thanks :D My reasoning as well, pre-heat the incoming water to the geyser, leave the existing geyser in place and that way increase the content of hot water available.

Did the installer do any calculations regarding optimum elevation angle for the panels? I presume the panels point true North?

Geoff
 

Sinbad

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This is the ideal way to do it IMHO

The only problem with is that in the days of the eskom subsidies for solar, you had to remove the non-solar geyser or disconnect it to qualify for the subsidy.

for the record, my solar vac tube system boils in summer. Geyserwise reads 99.
 

Geoff.D

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This is the ideal way to do it IMHO

The only problem with is that in the days of the eskom subsidies for solar, you had to remove the non-solar geyser or disconnect it to qualify for the subsidy.

for the record, my solar vac tube system boils in summer. Geyserwise reads 99.

You can always deploy a temperature controlled sun shade over the panels!:crylaugh:
I presume the hot water that escapes when it boils is collected somehow for re-use. ;)
 

Sinbad

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You can always deploy a temperature controlled sun shade over the panels!:crylaugh:
I presume the hot water that escapes when it boils is collected somehow for re-use. ;)

It waters the garden :erm:
 

qscwbt

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ha ha well the panel is true north.
and yes it waters the garden via the gutter lol
 

rietrot

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This is the ideal way to do it IMHO

The only problem with is that in the days of the eskom subsidies for solar, you had to remove the non-solar geyser or disconnect it to qualify for the subsidy.

for the record, my solar vac tube system boils in summer. Geyserwise reads 99.
Interesting mine only goes into the seventies and I heard somewhere that it wasn't possible for then to reach boiling point.
 

Sinbad

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Interesting mine only goes into the seventies and I heard somewhere that it wasn't possible for then to reach boiling point.

I'll try get video of the steam and water shooting out the vent
 

Geoff.D

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My simple little home built solar heater is used for demonstrating the technology easily reached boiling point! I used it to show that that the theory about pointing is pretty important. Facing True North, with the elevation angle equal to the latitude of the location will reach boiling point. Change the elevation angle by about 10 degrees and the water will not reach boiling point.
 

Sinbad

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My simple little home built solar heater is used for demonstrating the technology easily reached boiling point! I used it to show that that the theory about pointing is pretty important. Facing True North, with the elevation angle equal to the latitude of the location will reach boiling point. Change the elevation angle by about 10 degrees and the water will not reach boiling point.

Mine faces east... just saying ;)
 

qscwbt

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on solar vacuum tubes there is direct and indirect systems. some filled with alcohol some with antifreeze. So there is different types
 
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