If you still have the old metal radiator, I would consider it a "heritage" item worthy of repair or at least a clean out and flow test, before considering a replacement. The old-school way was to "recore" it, which returns it to new condition and sure there are still ways of getting this done.

Be sure the thermostat is fully closing too, as a thermostat that never fully closes can be as bad as one that never fully opens. If you are seeing score marks on that center post it is a hint that it might be jamming in certain positions as well.

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