Only 3 fins getting hot?

Tony_44

My apologies to the regulars on this board as I know I've seen this question here before but I can't find it in the archives and now it's happening to me.



One of my radiators will only get hot up until about the third fin.

It is the fourth on a line of five upstairs and the fifth one is working fine.

The radiator is tilted back to the valve. The vent is open all the way.

The pipe and valve get very hot and, as I say, the first few fins. I can hear definite churning and gurgling from the pipe leading in from the first floor, (I hear some of this from other pipes in the house where the radiators seem to work fine).



Any clues are much appreciated.

Thanks!

Tony

crash2009

Have

you tried swapping the vents, between 4 and 5?  WEAR GLOVES

Rod

"Problem" radiator

Hi- I'll add to Crash's post, "and make sure the burner is turned off and there is no steam pressure in the steam lines." Live steam can give you a very bad burn!

Tell us a little more about the 5 radiators on the line. Is the "problem" radiator larger or smaller than the others? What type of radiator vents do you have on these radiators? Are they adjustable? As Crash recommended swap the vent on the "problem" radiator with one a vent you know is good. That will determine if the problem is with that "problem" radiator's vent.

- Rod

Tony_44

Tried switching the vents ... no luck

Thanks guys.

I just got around to playing around with the vent on this radiator. The vent on the problem radiator is a vari-vent - no numbers just a slider to open and close it. I have these on some other radiators and, if anything, the don't restrict air enough as opposed to too much. In any case there was no change when I switched the vent with the one from the last radiator on the line (not sure of the exact kind of vent that one had but it has the adjustable disc on the bottom with the numbers on it - much more reliable in my experience).

I even ran the system a bit with NO vent in that radiator to see what would happen and as I suspected, nothing did. There just doesn't seem to be anything getting to that end of the radiator - only heavy breathing.

The problem radiator is about the same size as the others. I managed to jack both sides of the radiator up another 1/2" or so, still retaining the right tilt back and now I'm getting another couple of fins hot but still only half the radiator.

Other than the gurgling I mentioned in my original post. I'm not hearing any banging.

The only other thing I can think of is that this radiator was moved within the room at some point and there is definitely a section of the pipe (one-pipe system) that runs about 3 feet horizontal under the floorboards before it pops up at the radiator. Could that be the problem?

thanks again.

Tony

jpf321

what changed?

were you doing anything else to the system? insulating pipes? replacing boiler?



is it possible that your t-stat is shutting off before more of the radiator is heated? this is perfectly acceptable this time of year. crank your t-stat up 10dF and see if more gets heated .. if you dare.

Big-Al_2

Boiler Size

It's possible that your boiler just isn't quite big enough to keep all of the radiators full of steam, and because of some difference in piping, that's the one that fills the last.  If you want to bias the steam flow toward a particular radiator, sometimes it isn't enough just to vent that one faster. . . . You might also need to slow the venting on the others.