High recovery cylinders and excessive stratification?

[JonathanM]

I've just been watching a Youtube video of a heating engineer fitting a 125 litre high recovery cylinder.

At one point in the video, he seems to be saying that if you run the coil on these cylinders at a high temperature, you will often end up with excessive stratification. So, the NTC sensor might be set to 60C, but the water from the taps coming from the top of the tank is dangerously hot at over 70C. Is this to be expected?

 

[Johntheo5]

Yes, I would think so, these high recovery coils run with boiler flow temperatures of 80/85C, even my own 150L ~ 8kw (effective coil) gives a 5/7C difference. On a HW tap only, I wonder how much higher the scalding effect is with 70C vs 60C, I suppose it could be plumbed with the coil flow upwards to give plenty destratification?.