Water – Why is the hot water baseboard heater not heating


I have classic cast iron radiators in my house and then one "modern" one pictured below. It was installed in the 80s from what I know. It doesn't seem to produce much heat at all.

It is properly bled and the incoming pipe is hot but the outgoing pipe is only slightly warm. The radiator itself is only a bit warm on the incoming side.

BTW, it is on the second floor of the house where I also have a cast iron radiator which works great, so it's probably not a matter of water pressure or anything like that.

I'm not familiar with these radiators, are they not supposed to be hot when you touch them? Or is something wrong with this particular one? What could be wrong?

Should I change it with something better? What? A modern radiator? Used cast iron one? What would you do?

with cover without cover

(Edit: changed the title, because these seem to be called 'hot water baseboard heters')

Best Answer

This type of radiator should be warm to the touch, not hot like an cast iron radiator. If you touch the fins with two or three fingers it should feel hot enough to be very uncomfortable. Lastly, go to incoming pipe coming up through the floor again, it should be very hot, too hot to touch for more than a few seconds. Usually the water moving through the pipe is 150F to 180F. Then feel the outgoing pipe again, it should be almost as hot as the incoming side. If the outgoing is not hot you have a blockage or bad circulater. You should not be able to hold your fingers on either the in or out flow side these pipes for more than a few seconds. If you have a automatic bleeder on the radiator get rid of it and install a manual bleeder. Then run heat and bleed again. Then again one hour later.