let me try that again

the pocket for the  temp probe on those units sits aprox half way on the side . as is the element .

since hot water rises it may be 60 at the very top of tank and 40 half way and 20 at the bottom (stratification is the big word)

since the temp probe is halfway (middle ) its giving somewhat of a false reading

it can say 40 but If I measure it its 60 .

sorry for the confusion but just to add  petrol to  the fire , it also depends on whether its heated with element or solar

1 hour ago, SilverNodashi said:

if i had to go for it again it would be a no-brainer which one to buy - i blame my decision to go for flat plate squarely on the lack of expertise an or knowledge of the solar 'expert' - and of course my own lack of knowledge.

I agree but also the money. ev is more expensive than flat plate. funny the salesman told me that the ev tubes are designed for overseas as they make the water too hot in sa, yeah right

On 7/14/2017 at 11:04 AM, maxomill said:

stratification is the big word)

True, the formula I posted earlier works on the average temperature in the tank, and it's probably close enough. It's good enough to work out the amount of electricity you need if you know how much hot water you use per day and roughly in what percentages it is mixed with cold water :-)