I just got my cooling system welded together today. I'll take photos to clarify, but will describe it first.
I mounted a five column steam radiator outside the building on an existing concrete block three feet high. (It's a true 'yard' of concrete.) The radiator is standing at right angles to the wall and is plumbed straight through the wall with galvanised pipe. Inch and a half on top and inch and a quarter on the bottom.
These stubs come through the wall to the engine, BUT, the bottom line, the one going to the engine intake, tees into a ten gallon propane tank, near the bottom, with a 24 inch 'neck' sticking up to radiator water level. That's the filler neck and will have a clear sight tube running up the side. This neck will have a welded fitting to recieve the steam, if any, from the top steam tap of the radiator. THis will keep the system air free except for an inch at the top of the filler pipe where an overflow tube goes to a small plastic tank like a car has.
With a little fluid in this overflow tank the system becomes a 'closed loop', thermo-siphon system with a small radiator, but a BIG bottom 'radiator hose'.
I'm going to weld in a couple more small fittings in the tank in various handy places case I want to install a thermometer or auto cut-off switch for if the water runs out....
What it does is add ten gallons of cooling capacity to what was just a four gallon radiator. On hot days it'll need the extra coolant and on cold days the ten gallons inside helps heat the room.
.... or that's what's planned anyhow. Pictures soon.