350ltrs of primary water, what size should the header tank be

[Mike2007]

350 litres of stored primary water, which should be about 4 gallon of expansion at its worst. What capacity should the header tank be on this heat store?

 

[bellairaphon]

All depends on how fast it fills. In theory if your removing 1 l/s and the tank is been filled at 1 l/s then a one litre header thank would be enough. But if you have 9 l/s coming in and your draw off is 12 l/s then that's net 3 l/s of storage. so if you had a 10 min shower it would be 3x10=30l/s. It's hard to work out for you so you can play around with the numbers to suit your needs.

Nath

 

[Agile]

I think he is only sizing an expansion tank on an open vented thermal store!

 

[Mike2007]

I think he is only sizing an expansion tank on an open vented thermal store!

Basically if the header already contains 4 gallon and the primary water expands by 4 gallon the header will overflow and top up once cooled down. If this happened often too much oxygen would be getting into the heating water and would cause corrosion on the ferrous metals in system.