Anyone using IDWH with back up 4500W element

bob eck

When installing a high efficiency combi boiler is anyone running the domestic hot water into an electric water heater and then out to the faucets?
Trouble with combi boilers is when the combi boiler goes down you are not only out of heat you also do not have domestic hot water.
Using an electric water heater with an combi boiler when the combi boiler goes down and if it takes a few days to get the correct part in at least the home owner can still have domestic hot water.
When installing condensing boiler only or for that matter any oil or gas boiler with an indirect water heater if the boiler goes down the IDWH is also out of hot water.
Anyone installing IDWH with back up electric element so if the boiler goes down the homeowner can still have domestic hot water.
I know Vaughn has an option to install an element in their indirect water heater are there any other brand of indirect water heaters on the market that you can get an electric element in it?
Bradford White has solar water heaters that also has a coil and electric element in it but these tanks are 60 gallons and bigger.
Any other IDWH brands that have an electric element in it?
I see HTP also has solar tanks with back up electric. I take it most solar storage tanks will have a coil in it and have back up electric or back up gas.

Solid_Fuel_Man

Heat-Flo solar. Single coil with electric backup, best of both worlds. Buy most here in maine take advantage for the $750 rebate and install hybrid water heaters.