Switching radiators layman question

bosshog23

I am a layman with one pipe steam. I want to remove a radiator next to a window and replace it with one that will fit under the window to create a little more space in a bedroom. In other words change a 26 inch tall radiator with a 23 inch tall one.  After visiting many salvage yards, I found a 23 inch radiator about the same edr as my 26 inch but is is a hot water radiator with 3/4 inch threads. My existing  pipe and valve are 1 and 1/4. Is that a problem for the steam to go from 1 and 1/4 inch down to 3/4 inch? Thank you for your time.

Big-Al_2

Bushing?

If you have a 1 1/4" inlet valve, I'm going to assume that you have a single pipe system.  In that case, yes, you will need to have a full-sized connection to let the condensate drain back underneath the incoming steam.  You will also need a tapping partway up the opposite end for an air vent.

Does your replacement radiator have a large bottom connection that is bushed down to 3/4"? That would be typical.  If so, the bushing can be removed.  It will probably be rusted in pretty tight, so if you can't unscrew it, come back here and we will share our tricks for that sort of thing.