flow or return water goes to DHW he?

[bluesky]

dear all, i am studying gas safe now, i opened a friend's vaillant boiler yesterday and found that the divert valve is on the return way back to boiler, does this mean actually the return central heating water goes to secondary heat exchanger and is warming up the DHW tap water?

this must be a silly question for you, any help is appreciated,

cheers

 

[Billy Bob Bob]

flow is normally on the return in most combis,so probably waters being pumped into the dv

 

[bluesky]

hi gasman, could you tell more please, my trainer told me that water heated in main heat exchanger and goes to secondry heat exchanger once the flow switch detects the water flow, but my understanding is the divert valve should be at the outlet of the main heat exchanger, so when i saw the divert valve is at the inlet of main heat exchanger i was bit surprised...

 

[Billy Bob Bob]

diverter will be on the flow,pump on the return pushing trough the main heat exchanger when a demand for hot water occurs a diaphragm boiler (baxi 105 he for example) water runs trough 2 small pipes on the diaphragm pushs discs at pre set locations in the dv body this pushes primary water trough the plate heat which is a honey comb affair very hot primary water runs very close to but not mix with secondary water (cold main) comes out the other side hot (dhw)
look here http://manuals.aonly.com/index.php?d=Boilers/Baxi at functional flow diagrams for a better under standing scroll down and click on baxi 105 e installmanual

 

[Howsie]

Hot water in a combi is heated by a secondary water to water heat exchanger. Some boilers have an automatic bypass valve which connects the two just in case all the rads are shut.

 

[fuzzy]

diverter valve on flow to main heat x?