Heat exchange rate in cylinder

[Johnyc86]

Just a fast one for the experts

Does say heating water entering coil in hw cylinder heat the dhw faster if say the heating presure is say a bar and a half as oppose to f and e.
Also if hw cylinder was unvented would speed up heat transfer aswell??

Thanks in advance if i get a reply

 

[ShaunCorbs]

That depends on setup in theory with both the same flow rate no as a copper cylinder can normally only do 5-7 kw

And unvented normally can do 20kw as the coil surface area is more