I have a oil boiler with a very small reserve for the hot water. I don't take long showers and I have never been able to get a good full very warm shower with this boiler. For years I have seen various sizes of Point of Use eletric water heaters that all show they can be used solo or inline with boilers or other hot water so I figured why not just do this with a 30 gallon electic unit.
A few years ago I interupted the line for the hot water and in line I added the 30 gallon water heater. Showers have been very good for the whole family, but I am now wondering if I am throwing money away by having this 30 gallon reserve instead of just installing one of those 4 - 6 gallon mini units at Home Depot.