How much is enough?

[singletrack800]

Looking to replace old (15 yrs approx) boiler with a new combi. 4 bed house. Boiler on ground floor, bathroom on first floor. May convert loft in future. Want to rid cold water tank in loft if possible. Have been looking at WB 37CDi & WB 42CDi.

Do I need to go the extra £250 for the 42 CDi to get enough DHW? For example; will the 2 litres difference make a difference to the shower if someone in the kitchen decides to turn the HW tap on? And what about a loft conversion? Am I likely to need a Megaflo regardless of which boiler I choose? I've been told by british gas that the mains pressure is about 18 l/min.

Thanks

 

[Breesey]

An old argument, but just go straight for an unvented HWC (Oso!) with a nice dinky new Alpha 24 heat only boiler.

 

[simond]

If you only have 18l/m then an unvented will not deliver an appreciably different performance to the 42Cdi.

Can't understand Breesy's logic