Old restored cast iron style radiators can they be used with outdoor bolier

[northernlights]

Restored cast iron style radiators with out door boiler , restoring farmhouse

 

[Del_]

I'm pretty sure that cast iron radiators aren't real concerned about their source of hot water.

 

[nedsim]

Restored cast iron style radiators with out door boiler , restoring farmhouse

The potential problem with an unpressurized open system, as I believe most OWB's are, is that fresh oxygen is constantly introduced into the boiler loop from the atmosphere and in the make-up water. The oxygen rusts any iron or steel in the system. In a properly operating closed and pressurized boiler the supply of oxygen is limited and bound up in rust pretty quickly, so the amount of corrosion is limited. I won't venture whether this is an actual problem in an open system that's monitored and maintained with boiler treatment chemicals, etc. Since cast iron is generally more resistant to rust than steel, I'd speculate the boiler itself and any black iron pipe is more likely to have problems than the radiators.

 

[Bill G]

Restored cast iron style radiators with out door boiler , restoring farmhouse

I assume you do not plan on cooling the house?

 

[j-jock]

Restored cast iron style radiators with out door boiler , restoring farmhouse

I have been running a wood/electric/propane hot water heating system for just short of 50 years. The cast iron registers, will work well in any closed system. The disadvantage is, that they have a larger water capacity, and they have a slower response time to heating demands than the equivalent copper baseboard heater.
Corrosion is not a problem where I live, and the amount of fresh water that gets added to a hot water system in a year would not be enough to make corrosion a problem.
As previously stated, my house is hot water heated, using a wood fired boiler, with electric and propane boilers as a backup. It is a closed system, and uses a recirculating pump, but because the heat is constant in a wood burning system, and I had replaced all the large cast iron registers with copper base board registers, the water normally circulates in my system without the circulating pump on.
If you are installing the system from scratch, you need to have over pressure release on the heating coil above the boiler, and you also need a 5 gal expansion tank in the system. The expansion tank must be able to withstand the maximum system pressure.
You also require a fresh water supply connected and under pressure to replace the system water that gets lost during the normal cycling. There is a special pressure reducer available, that connects to the pressurized city water system, or your pressurized well water system. You must have this, or the system will develop an air lock, and hot water circulation will stop.