Understanding water flow Y-Plan HW & CH System

[minirock]

Hi All,

Have a fairly old Y-Plan system.

Baxi Bermuda 401 back back boiler, fully pumped (only two pipes coming from boiler.
3 Port mid positon Valve
Hot Water Cyclinder, with Water tank directly above it, which feeds into cylinder.
Smaller tank in loft that feeds CH system??

Question, does the water between the 2 systems get mixed?
For example, is water that has been flowing around the radiators going to be mixed with water in the Hot water cylinder?
So any additives added to CH system, will also go in to HW system?

Thanks!

 

[Dan Robinson]

No. It is separated. heating water goes through a coil inside the cylinder.

Unless you have a Primatic, in which case.... its different.

 

[Armo74]

No they do not mix. The small feed and expansion tank feeds the heating and the larger CWSC feeds the hot water in your cylinder.

 

[minirock]

Ahh , all makes sense now!

I presumed that water directly heated by the boiler was going into the cylinder.
But in fact it goes round a coil in the cylinder, which heats the water in the cylinder indirectly before going back down to the boiler to be reheated!

Correct?

 

[Armo74]

That is correct, Hence why it's called an indirect cylinder.

 

[minirock]

Thanks all.

Never like the thought of bath water sludging round the old boiler, but it doesn't!
Great!