A couple recent threads concerning domestic hot water strategies made me remember that turning an electric hot water heater back on after heating your DHW with wood for awhile can involve more than just flipping the breaker. Electric hot water heaters have several safety mechanisms built in. One is a heat-activated breaker on the thermostat module. If you exceed the setpoint, which I believe is around 190 or 200 degrees, the beaker opens, cutting power to the heating elements. If you managed to trip that breaker at some point while heating the tank with the wood boiler, then you will need to reset the breaker on the thermostat by removing the cover and pushing the little round button (firmly) with a screwdriver until it clicks. Or, you can be like me, and tear your whole water heater apart looking for the problem and blowing an element in the process...... The other thermal safety feature is a temp sensor built into the pressure relief valve. At a certain (pretty high) temp, it will cause the relief valve to open, generally resulting in a wet, steamy floor. If this is a problem for you, there are ways around it, but I'm not going to discuss them in a public forum, because this is an important safety feature that shouldn't be overridden.