Potterton Performa 28i

[rymacg]

Ok thanks very much I think I've got it now, what confused me was thinking the internal exp tank was there to allow the water in the CH to expand and retract but this obviously not the case.

 

[hertsboilers]

Ok thanks very much I think I've got it now, what confused me was thinking the internal exp tank was there to allow the water in the CH to expand and retract but this obviously not the case.

For most boilers the internal expansion vessels are there for the water in central heating to expand and retract, but for this particular model, the expansion vessel also has another function to store pre heated energy for instant hot water.

That is why this model is called "i", instant.

 

[rymacg]

Really appreciate you getting back to me hertsboiler, looking at the manual for the 28i it shows that in CH mode the internal exp vessel is not included in CH circuit only the DHW circuit and this is where it confused me, sorry if I sound like I'm thick but I was just trying to understand how the boiler works. As I said earlier in my post CH heating has never worked better since I fitted the external Exp vessel. Thanks again.

 

[hertsboilers]

In CH mode, same as DHW pre heat mode, the expansion vessel is connected to the central heating by the path I marked as red.

 

[rymacg]

Ok that's much clearer now , thanks for taking the time to explain. If Potterton had shown this in their CH Mode diagram maybe I would have understood sooner. Thanks again.