Hi, I have a new build and the gas plumber recommended that I install two infinity system, one on each end of the house as he figured that a single A26 unit is not sufficient for 4-5 bathroom house with washing machine, taps etc. Houses similar size in the area seem to have only one A26 unit so not sure if plumber is just upselling or actually true. I could consider upgrading to a single bigger unit but he insists that putting two will heat water faster and actually save on the water bill which would offset the initial cost (~3400 extra)

Thoughts?