Cast iron baseboard wont heat up

oopsplumber

I have an issue with some cast iron baseboard heat not heating up quickly or evenly. The rest of the house works great. On the 2nd floor of the building someone installed 20' of cast iron base. I replaced the valve and the steam trap. The rad is pitched properly with no sags. The condensate return is clear on the leaving side. The radiator is also not blocked but the steam does not make it across the radiator ending about 1/2 way. All the other radiators are somking hot and this one is 1/2 warm. It is a (2) pipe system fed with 3/4 in and the condenstate return is 1/2 inch. I am kind of thinking that it is just a poor design and the steam cant make it across such a large run.....But I need some input before I make that call...... Any thoughts ??????????

Long Beach Ed

Return

Where does the 1/2" return line from the baseboard end up?  If it goes to a place where there's steam, (like a dry return with other failed traps) you'll have problems. 



Check your other traps.

oopsplumber

Cast iron baseboard wont heat up

So your saying that if everything else is functioning as it shoud....this rad should warm right up????

Long Beach Ed

Why not?

Did it ever?  



Twenty feet of iron baseboard should have about 60 feet of EDR.  The 3/4" horizontal runout to it should just about handle that load, but the vertical riser should be sized bigger, like one inch.  If the vertical riser from the basement's 3/4" also, that may be your problem.  A 3/4" vertical supply is said to handle only about half the radiation you've got there. 



Is the radiator pitched?  Pitching it hard toward the return may help. 



But if you've never seen that radiator work, it perhaps never did and replacing the vertical riser with a 1" pipe should improve its performance.

Steamhead

Either that

or there's a partial obstruction in the return, such as a water pocket. Or the traps didn't have the throughput that the other traps in the system do. Something is limiting the air escaping from that baseboard.