On 21/05/2017 12:11, John Rumm wrote:

I found a 35kW combi will do a pair of showers concurrently. Not going
to do 4 obviously - but its unlikely in a domestic setting that all 4
would be in use at exactly the same time.

Same findings here with a 36kW combi.

2 showers no problem. Biggest issue for me would be flow if another
tap/flush/washing-machine etc wanted water at the same time as we're
atop a hill and the waterboard won't up the pressure past 3.5 bar as it
causes problems for them down the bottom.