Definitely YES. In order to get ANY hot water from them, and even that is problematical, you need a LOT of watts and they can only be supplied with a dedicated line and circuit breaker. Personally, I think even most 240 volt units are worthless, so you can tell what I think of 115 volt units. Unless you reduce the flow to a "pittance" using the supplied faucet aerators, you will NOT get any hot water, but warm maybe, from ANY "on demand water heater".