Boiler still heating water despite immersion having recently heated the water

[Andy165]

As soon as you draw off hot water, it is being replaced by incoming cold water which at this time of the year is about 9c or less. That then has to brought up to 60c by mixing with the existing water and being reheated. Two showers from a mixer shower and you could use 60 litres of hot water which needs to be replenished. Hence boiler firing to reheat.

 

[JohnD]

As soon as you draw off hot water, it is being replaced by incoming cold water which at this time of the year is about 9c or less. That then has to brought up to 60c by mixing with the existing water and being reheated....

Cold water entering a cylinder does not mix with the existing hot. It stratifies and lies at the bottom of the cylinder.

This stratification allows you to draw almost the entire volume of hot water before the cylinder is fully cold.

 

[UKMO]

Cold water entering a cylinder does not mix with the existing hot. It stratifies and lies at the bottom of the cylinder.

This stratification allows you to draw almost the entire volume of hot water before the cylinder is fully cold.

Thanks for this clarification. I have been confused as to why the cylinder would heat up then, as soon as any hot water is used, allow cold water to enter and mix with the hot water thus immediately cooling it down and making the previous heating up pointless. This seemed a ridiculous way of a cylinder operating to me. Your clarification makes sense and also is reassuring that I’m not wasting energy and money

 

[dilalio]