Bosch instant hot water system

[basil]

How do I connect a portable 240 volt generator to the bosch hot water system during a power outage. The system is already hooked up mains power

 

[havasu]

I'll be perfectly honest with you. Water and electricity don't mix, and can kill if done incorrectly. I would recommend having a professional come out to give you the proper advice.

 

[Caduceus]

Yes, I agree with havasu. Trying to rig something will create a safety hazard. Look at it this way. You will be trying to feed power into your electrical system so how do you separate the distribution of power from your breaker panel and the rest of the house? What will happen when power suddenly comes back on while the generator is hooked up?
Back-up generators (liquid fuel and natural gas) are available, but even then an electrician must properly install all of the relays and bypasses associated with the safe operation of the system.