Difference in hot water

[Sanke]

Hi all
Had email form customer today saying that when he has heating on his hot water is much hotter than one heating not on Anybody got any ideas as to why ?

 

[kay-jay]

i had this the other week! was a baxi he 105 boiler which has a preheat function? apparently when central heating is on it uses heat from the primary circuit to preheat a certain volume of water destined for the hot water supply which according to the manual is delivered at 65 degrees. one of the dials on the front of the boiler can supposedly turn off the preheat function but it didn't make much difference on this particular boiler.

KJ

 

[Sanke]

This is a worcester greenstar

 

[Puddle]

Well when heating on initially the hot water will be hotter as main flow pre heated

Could be he is loosing a bit of heat through to cold heating circuit when heating off

or be gas supply undersized to unit,as regard required output for hot water and when heating on,the hot heating pipework is helping heat output for hot water

or could even be flow rate is down when he has his heating on as in peak demand in morning and evening periods

just some thoughts .........