Solar opinions

[isie]

Also in Gauteng . Last night ambient was 16 to 19C at 8pm . You posted a pic of 16C. Makes me wonder where you actually put the temp pickup for the tuya

Its inside the geyser
If you trying to hint I somehow put the temp sensor on the outside of the geyser I assure you I didn't - I don't expect you to trust me in fact there is no possible way for me to do this
Geyser wise

where is your sensor placed?

If you had just showered, even with cold being fed in at the bottom you would have quit long before then because it was cold.

It was a while after we showered and water temp had dropped - remember we switching on the element only certain times so inevitably on many days in winter it will need to use more then 3.5Kw and if the morning it will be using power from the batteries and or grid.

When I still used a 200L geyser even after multi people used it the average it went down to was 30 to 35

In summer mine is the same - in winter its a different story - when did you measure

Doesnt change the fact that PTC is better tech than resistive based tech. But to each his own.

Also you dont seem to understand how PTC components actually work.
Here is a resistance vs temperature graph that explains PTC's in general

View attachment 1744387
This kind of breaks down your argument that PTC will take far longer to heat up water under a certain temperature.

My argument was(based on the information from the manufacturer) it will user more power under <25C so if your intention is to preserve battery this is something to consider

Quite the opposite. Under a certain temp the internal resistance stays fairly low , in other words allowing a higher amount of current to heat which is fairly stable until a temperature reference point is met , after which the internal resistance increases lower the power consumed.
A far safer tech all round compared to resistive heating.

I'm not discounting the data all I asked was based on the information provided its only 10-15% more efficient is it worth the extra cost

 

[isie]

 

[tetrasect]

For those interested in the PTC story Got a call from the guys at Geyser wise gave pretty simple honest explanation.

First thing the PTC is only about 10 or 15% more efficient then a standard geyser, so no a 2KW PTC will not be worthwhile to replace if you currently have a 3KW, its still going to take forever to heat up.

The way it works is the higher the temperature the lower its power requirement (not that if will work in a geyser but testing in air at over 260C it KW requirement is apparently close to 0) this is internal resistance story.

On the opposite end the lower the temp the more power it will require if water temp is less then 25C then it will actually use more then 3kw as temp increases its internal resistance increases that's when the kw requirement decreases ,so in summer sure it will use less but Eish this winter water temps going to actually use more power till it hits 25C.

Also things to add to cost need to replace flange as well as it doesn't fit in a standard element pocket in most geysers they did mention though once its installed if you need to replace it then you don't have to drain the geyser because of this.

So now is it worth the cost for the 10-15% efficiency?

They are lying.

PTC is not more efficient. All resistive heaters are basically 100% efficient, which is also a hard limit.

To get above that you need to make use of temperature differentials like a heat pump does.

Heat pumps can reach as high as 600% efficiency, meaning for 1kw of input power you get 6kw of heating power.

PTC just means it is self-regulating since it's resistance increases with temperature. It's basically like turning the heating power down as it gets hotter.

Self-regulating heater - Wikipedia

en.wikipedia.org

 

[Next Thing]

Heat Up Test

This test determines the percentage energy saved when using an XTEND PTC Ceramic element compared to a standard resistive spiral element..

xtendelements.co.za

Heat Distribution Test

This test shows that using the same amount of energy, a higher final average temperature can be reached using the XTEND range.

xtendelements.co.za

Has been posted before on MBB

 

[tetrasect]

Heat Up Test

This test determines the percentage energy saved when using an XTEND PTC Ceramic element compared to a standard resistive spiral element..

xtendelements.co.za

Heat Distribution Test

This test shows that using the same amount of energy, a higher final average temperature can be reached using the XTEND range.

xtendelements.co.za

BS.

And "independent" my ass.

 

[Speedster]

Heat Up Test

This test determines the percentage energy saved when using an XTEND PTC Ceramic element compared to a standard resistive spiral element..

xtendelements.co.za

Heat Distribution Test

This test shows that using the same amount of energy, a higher final average temperature can be reached using the XTEND range.

xtendelements.co.za

Has been posted before on MBB

Snake oil

 

[tetrasect]

Snake oil

It says they measured the "average temperature" while draining the geyser.

That's not the way to do science.

 

[Speedster]

It says they measured the "average temperature" while draining the geyser.

That's not the way to do science.

Agreed. If there was legit a technology that achieved more than 100% heating efficiency it would have been widely adopted around the world already. In the absence of any independent testing there is no reason to believe their claims.

 

[Next Thing]

So go redo the tests with your own methology in laboratory conditions and write up the results.
I know why they said average and with a bit of thought you can figure it out as well.
As long as teh average was done the same way in all 3 cases then what you think is irrelevant

I challenge you to go find an equivalent laboratory test that shows the complete opposite.

If there was legit a technology that achieved more than 100% heating effeciency

You have allready made an incorrect assumption

 

[Speedster]

So go redo the tests with your own methology in laboratory conditions and write up the results.
I know why they said average and with a bit of thought you can figure it out as well.
As long as teh average was done the same way in all 3 cases then what you think is irrelevant

I challenge you to go find an equivalent laboratory test that shows the complete opposite.


You have allready made an incorrect assumption

Please enlighten me by correcting my incorrect assumption

 

[Next Thing]

Please enlighten me by correcting my incorrect assumption

If a heatpump can produce the same heating at a lesser power requirement, doesnt that make it more than 100% efficient compared to a resistive heater ?
Yes in ideal terms a resistive heater is 100% efficient. ( it uses all input power and makes an equivant output power, in heat ). But so does a PTC based on those terms. In those broad terms a heatpump is actually less efficient due to losses from mechanical items.
You have assumed a result based on a singular view of a items operation

And before you think I am advocating heatpumps, Im not, They are really really crap in cold weather

Still waiting for a lab result disproving their lab results.. Or is it a "true me bro" ?

 

[Speedster]

If a heatpump can produce the same heating at a lesser power requirement, doesnt that make it more than 100% efficient compared to a resistive heater ?
Yes in ideal terms a resistive heater is 100% efficient. ( it uses all input power and makes an equivant output power, in heat ). But so does a PTC based on those terms. In those broad terms a heatpump is actually less efficient due to losses from mechanical items

Yes, a heat pump is more than 100% efficient. This is well known and a widely used technology. Unfortunately it is significantly more costly than an element, which is its major drawback. You will however still find heat pumps used across the world and available from multiple manufacturers.

The same can't be said for PTC. It is much, much cheaper than a heat pump and should, if indeed more effecient than an element, be a widely adopted technology.

 

[tetrasect]

If a heatpump can produce the same heating at a lesser power requirement, doesnt that make it more than 100% efficient compared to a resistive heater ?
Yes in ideal terms a resistive heater is 100% efficient. ( it uses all input power and makes an equivant output power, in heat ). But so does a PTC based on those terms. In those broad terms a heatpump is actually less efficient due to losses from mechanical items.
You have assumed a result based on a singular view of a items operation

A PTC element is a resistive heater. All resistive heaters are 100% efficient.

Joule heating - Wikipedia

en.wikipedia.org

 

[Next Thing]

A PTC element is a resistive heater. All resistive heaters are 100% efficient.

Joule heating - Wikipedia

en.wikipedia.org

Yes , and ?

 

[isie]

So go redo the tests with your own methology in laboratory conditions and write up the results.

You would think a company selling an over 3K device that they really believed worked would have no issue providing an independent accurate tests?

I challenge you to go find an equivalent laboratory test that shows the complete opposite.

I challenge you to go find an equivalent Independent laboratory test that shows a comparative between 2 geysers of the same volume , with the same volume of water , one with a standard element and one with an equivalent wattage PTC element - showing them heating water from the same base temperature to the same end temperature and the time each takes to reach said temperature.

 

[Next Thing]

Unfortunately it is significantly more costly than an element, which is its major drawback.

Which pays for itself due to long term savings.
There are actually bigger drawbacks than that

 

[Next Thing]

You would think a company selling an over 3K device that they really believed worked would have no issue providing an independent accurate tests?

I challenge you to go find an equivalent Independent laboratory test that shows a comparative between 2 geysers of the same volume , with the same volume of water , one with a standard element and one with an equivalent wattage PTC element - showing them heating water from the same base temperature to the same end temperature and the time each takes to reach said temperature.

Couldnt be bothered
I challenged you to find a opposite lab result. Go on.. Should be easy ... I would even settle for a neutral result ( Making it easier for you )
You have your own view you are projecting. Go find the evidence to support it. Not doing your work for you

 

[Speedster]

You would think a company selling an over 3K device that they really believed worked would have no issue providing an independent accurate tests?

I challenge you to go find an equivalent Independent laboratory test that shows a comparative between 2 geysers of the same volume , with the same volume of water , one with a standard element and one with an equivalent wattage PTC element - showing them heating water from the same base temperature to the same end temperature and the time each takes to reach said temperature.

The time is less of a factor. The important question is whether it uses less Wh. I don't for a moment believe that it does. There are a number of manufactures of PTC elements across the globe and Xtend are the only ones who claim improved efficiency. It would be a major selling point for all of them if true.

 

[Speedster]

Which pays for itself due to long term savings.
There are actually bigger drawbacks than that

Irrelevant to this discussion. And not always true.

 

[tetrasect]

Yes , and ?

So how can a resistance heater be "more efficient than a resistance heater" when all resistance heaters are 100% efficient?

You could put 20x 100W incandescent light bulbs in your geyser and get the exact same efficiency.

It's pretty basic physics.

I have provided two Wikipedia links to back this up.