Not correct, a pressurized tank will have a better flow rate than any combi.
My plumber is giving different advice. So please explain how a tank at mains presure can have a better flow rate than the mains themselves?
Surley the presure/flow can only be as good as the supply into the tank, its not like you can empty the tank faster than it fills as its a sealed system, hence why you can't have a pump.
This however does make sense
Their are 2 main advantages to a pressurised hot water tank over a combi boiler.
1. You have a large tank of water heated to a certain temperature also at mains pressure to feed into a shower this will remain constant all year around. A combi boiler has an ability to raise the temperature of the incoming mains water by a certain amount for a certain flow rate this tends to mean that with a correctly specified combi boiler you can have a nice powerfull hot shower in summer but in winter when the mains water can be as low as a few degrees your shower is either cooler or less powerfull.
2. The second point is that a combi boiler can react badly to sudden alterations in the demand for hot water so another tap being turned on can affect the amount of hot water going to the shower causing a spike in temperature either up or down.
I would dispute that if you are unhappy with a combi boiler run shower that you will also be unhappy with a pressurised shower. Their is a lot more to a good shower than just the boiler.
This makes more sense to me but having a combi in the current place I can't say I've experienced these issues. A thermostatic shower solves the winter/summer temperature issues and if the flow rate is less in the winter its impeceivable. The only issue with the combi is the supply to the house being crap but that would also affect a presurised system.