Most people believe that if something costs more, it has to be better quality. In the case of generic drugs, this is not true, says Gary Buehler, Director of FDA's Office of Generic Drugs. The standards for quality are the same for brand name and generic products..uch of FDA's review of generic drugs and brand name drugs is the same, Buehler explains (See Same FDA Requirements for Brand-Name and Generic Drugs below).
Then evaluate tank water heaters on the same gph basis to determine how many gallons of storage are needed to meet this demand. While tankless water heaters do not run out of hot water, if not sized correctly, the flow rate of that water can be adversely impacted.
With a combi boiler the hot water is at mains pressure so the flow rate to the shower will be good (but will never be higher than the boiler itself will allow). With a hot water cylinder, the pressure is significantly lower than mains pressure so the flow rate will be comparatively low.alculating for a bath: I calculate that if the cold tap is 10Â°C and the hot tap is 55Â°C, then you'll need 35 litres of cold and 85 litres of hot for 42Â°C bath water. The 100kBTU combi above is specified at 9.5 litres a minute for a 47Â°C rise (allowing 2Â°C loss in pipework, 55+2-10) and this will take 9 minutes to fill.