I have one of those amish electric "fireplace" heaters for my bathroom. In the winter it is quite cold in there so I wanted to be able to turn it on and off using a smart socket. The heater has electronic control that means it will not come on immediately when power is supplied to it. I modified the board inside to allow the heater to operate with a bypass switch.
The control board has a separate relay for each of the functions of the heater (elements, fan, lights, "fire" motor) so in order to bypass I had to energize the elements and fan relays. I couldn't connect the coils directly together as when you turn the heater off using the built in controls, it runs the fan alone for a couple of minutes to cool it down.
I took a 4 pole relay and a length of high temperature wire and connected it so that the bypass switch that I installed on the front of the heater would energize the relay I installed. The relay would then separately provide power to the 3 relays on the control board that I needed to energize. This way when the bypass switch is on, everything is on, but when it is in normal mode the controller still has individual control over each function.