Radiators may need flushing..or?

Hi,

I have a 30's Arco Model K vapor system. It's worked well since it was properly vented and adjusted by Steamhead and Gordo perhaps 15 years ago.

System always cycles off on temperature. Pressure stays at a max of about 3.5 ounces.

I would say that 12 out of the 16 radiators in this house remain cool at the lower half. And this is with orifices and valve stems wide open.

Any idea of why my lower halves remain cool?

The three Gorton #2's at the end of the system (sorry I forgot what it's called) always remain open.

So..I am always able to get the house to a comfortable temperature. But when I crank up the temp as an experiment, say to 76 degrees, and the radiators remain cool on the bottom isn't this abnormal?

I'm concerned from the standpoint of efficiency.

Note: 15 years ago I rebuilt all the old valves in the system. Now, a bunch of them are failing again and I am replacing them with Mepco SWRF-B's that have an adjustable orifice..

This radiator was recently removed, sandblasted and painted as it is going into a re-modeled kitchen. It will be removed again while the kitchen remodel is finished. Just wanted to re-fit it with new valve to make sure it works OK..

thanks,

Todd