Switching from system boiler, tank and water pump to combi boiler

You need to install a valve to give balanced hot & cold outlet pressures, fed straight from mains supply.

My colleague has a point. Also there are combi boilers that deliver good domestic hot water delivery. Like most heating solutions there will be several ways of satisfying the water requirements. Obviously a tank on the roof and a combi boiler to supply the hot side would be ineffective due to diffetential pressures acting on the shower. Usually the shower life span is deminished due to exvessive work by the thermostatic balancing valve. I could give two answers. One. Fit two 24 kw combi boilers. One for each floor. Or one boiler that we install that delivers 16.4 litres per minute with a temperature rise of 35 degrees. Which in most curcumstances be ok. Unless all are calling for water at the same time. Or stay with your system boiler and hot water storage unvented cylinder. Unless you want to invest in a floor standing combi. Heatflow type. This will do the trick and more. Hope our answers have helped but the old addage you get what you pay for is always written on the wall. Regards Combigas