After thinking about this for a while, I would set up the electric water heater so that your if your water temerature gets to low that it will turn on, also have a flow switch in the controls so that you dont freeze the water in your floor if the fire goes out or the pump stops. The other way around is is to run a glycol solution and make it a closed loop. I have done this in the past using an expansion tank and air eliminators at the high points of the system.
Yes, that was what I was thinking with regard to the electric heater to have it come in if I'm too lazy to fire the unit. I'm not too worried that the floor would ever freeze hard enough to bust the pex because the winters here are not that hard. I'm not saying it could never happen but it is highly unlikely and if there was ever a case that for some reason the electric went out and I couldn't keep the stove running I have it set up where I can blow the water out of the floor tubes and drain the water heater.
I was only thinking that a open system may be safer and easier to set up. Also I was thinking that I could capture rain water to use in the system because it should be cleaner and free of all the junk that is in the well water here. I don't know for a fact but I was thinking it would be a little easier on the medal inside the water jacket of the boiler.
My manifold system has air eliminators but I would have to add one to the water heater because it is going to be above the manifold setup. It is going to be sitting over top of an office space that houses the manifold. I plan on putting an expansion tank at the electric heater with an additional air eliminator there also.
