Cast iron radiators to aluminum wall panel radiators

bob eck

Home owner wants to replace old cast iron radiators with aluminum wall panel radiators.
Old system was gravity the boiler with pump.
Does the supply piping need to be changed if going to aluminum wall panel radiators?
What are the do and not do on this type of change out.

Jamie Hall

Working off theory here, @Bob eck, but... you will have your work cut out for you.

The pipes will probably be OK, provided of course that they go where you want them to, and also provided that you have a way to control the flow in them (that is, balancing valves). You're going to need that.

Where the work is going to come in is in getting anything like the overall comfort from the system. The cast iron gravity system was pretty well always on -- yes the radiators did change temperature somewhat, but they would have been pretty warm most of the time. The aluminium radiators have no heat capacity at all, and therefore when the pumps are running they'll be hot, and when the pumps are off, they'll be cold. You would be well advised to run the new system with a very well designed outdoor reset and a fully modulating system. That will give you somewhat the same effect.

Harvey Ramer

Agree with what Jamie said, and also size the rads to be as thin as possible and cover the largest amount of surface area the decor allows. This increases the ratio of radiation versus convection in the net output of the rad. Also put a TRV on each rad to balance the system.

Mark Eatherton

Watch your fluid pH. Aluminum requires a lower pH than does ferrous components...

ME