Combi replacemement - next size up?

[matthew.larkin]

If we've currently got an 8 year old Potterton Combi 100 boiler (which I believe is specc'ed as a 100btu boiler), and which when working supplies the house fine with heat and hot water, is there any reason why I should go any higher than a 30kwh boiler as a replacement?

Looking at the WB Greenstar 30CDi at the moment, but noted that their "calculator" often suggests a 37kwh option instead.

What's the tangible benefit (if there is one) of getting a combi boiler which supplies over-the-top power?

Matt

[John Rumm]

Better flow rate of hot water. The extra 7kW would give you another 3lpm of hot water, or a 30% reduction in the time taken to run a bath.

As long as the heating side can modulate over a decent range, then there is no real down side to having more power as long as you gas supply has the capacity.

[Ed Sirett]

It is also possible that the existing unit is _effectively_ operating at nowhere near the nominal 30kW rating. So that a similarly rated but nnew unit would give a very noticeable improvement.