I have a terraced house with capacity of 5 to 6 students. The boiler ( a combi) has broken down and I need to replace. What do you other landlords do? Do you go with a combi and then electric showers or do you go for a system boiler with unvented heated cylinder. I want to get this right but all plumbers just automatically assume I want a combi. There is no way a combi can provide adequate flow to two showers at the same time?