What size buffer for UFH w Grant Combi

[williamlincs]

Have had a search through old threads on a similar topic, and wanted to check I’ve understood correctly - apologies for rehashing old questions!

 

House is 170 sqm, 3 bed. UFH has been installed in 50 sqm of the property with 150mm PIR under screed. Rest of property is heated w rads. Boiler is a 32kw Grant Combi, occupants 2 adults 2 teenagers. Will a 120 ish litre buffer tank suffice for the UFH? Mains pressure is good, flow a little on low side, around 15 l/m, we are on a spur off the main feeding 3 properties, have spoken to salamander technical, wondering if we need an accumulator?

many thanks 

[joe90]

I was recommended a 90 litre buffer.

[CotswoldDoItUpper]

We have a 100l buffer with 230sqm house and 90sqm UFH and rads for the rest. Also a gas boiler, tho no idea of the size!! 
 

Seems to work ok and we have kept a reasonable amount of storage above it too! 
 

https://www.advanceappliances.co.uk/product/141-buffer-stores/