Had my immersion heater on overnight last night, water in tank is at 60 degrees,
get yourself a proper immersion heater waster of money and time with pond heaters, you need to change the title of this thread to "finally on luke warm water"
But saying that, surely 60 degrees is way too hot and would do damage to windows.
Im looking at just heating to about 34 degrees. At the moment im off work due to family illness, so ive a little time to play about. As i mentioned in first thread im not keen to cut into ny tank, im good at diy but it normally takes 2nd attempt to get right so i can see leaks springing here n there if i attempt it. My replacement heaters are due today so will test it out tonight.
I am pleased with my tank insulation though, because since yesterday morning when i last took the reading and turned off the heaters, ive just been out to take a temp reading and it was just short of 20. So within 24 hrs and no extra heating in van overnight, ive only lost a handfull of degrees of heat .
Unfortunately your knowledge of physics lets you down, other than a few inches on the top your water was never in the twenties
and its the same now, the water at the bottom of the tank cools down first as the heat rises to the top.
The important reading will be what's going through the pump at the bottom of the tank as it will be a more accurate reading
of what to expect.
That's the problem when using immersion heaters to heat static water, the top of the tank could be 30 degrees and the bottom could only be 10 degrees, to get the water at the bottom to 30 degrees the top will need to be a lot higher, on demand is the only way to get an accurate constant temperature flow.