I found the information in the link that you supplied to be not very accurate.

Baseboard hot water systems (copper tube with aluminum fins and sheet metal outside baffles) work based on convection. They can provide even heat with fewer cold spots and hot blasts of air that a forced air system, for example.

Radiators also work based on convection - which isn't as even as baseboards because they aren't as distributed -- and as their name implies, they also heat using radiation.

Radiated heat can make a person feel warm - even when the air is cool. Thus, there are some advantages to using radiant heat in certain situations.

I don't understand the claimed advantage to cast iron baseboards. Are they claiming to heat both with radiant heat and convection?

They both heat the same way. The metal gets hot and heats the surrounding air. Because warm air rises, it creates some circulation (aka convection) in the room. That is one reason why radiators are typically located under windows, as the temperature differences enhance the convection effect.

No, there is a substantial difference  cast iron's heat capacity is several times higher than that of aluminum. It takes a lot longer to heat up, and then it takes a lot longer to cool down. (This quality of cast iron is also exploited in making cookware and disc brakes, for example.)

For this reason it does not heat up the air as much as aluminum, and therefore there is much higher radiant heat component, than convection. Also, for the same reason, the fluctuations in temperature are much smaller  and the fluctuations are what's causing discomfort to humans. We hate it, when the heat kicks in (temperature rising quickly), and we don't like it, when it turns off (because temperature falls quicker as aluminum baseboards give up all the heat they had).

Now, back to my original question, where do I get them? Thanks!

There is no more heat capacity, BTU output per foot of CI baseboard, than a quality fin-tube copper baseboard. They both put out about 580 BTU's per foot at 180 Fahrenheit water temp.

It just radiates longer with less temp swings, besides being quieter if system is designed right

There is more heat capacity in cast iron (about twice more than in typical stainless steel, far more than in copper or aluminum), which is the reason for lower temperature swings and for more of their heat being transmitted through (infra-red) radiation.

Heat capacity is the measure of inertia not unlike mass  a heavier vehicle will take longer to get going (by the same engine) and will be take longer to stop (with the same breaks) than a lighter vehicle. Its starts/stops will thus be a lot smoother.

Similarly, a ping-pong ball will jump and bounce off of any little scratch, while the bowling ball will just roll straight...

I'll shut up on the matter now  this forum is hardly a place for Physics lessons...

That last post certainly explains how you got the screen name "Doofus",

As misguided as I think the question is...

an answer is http://www.runtalnorthamerica.com/

or you can google steam radiators and get some answers

an answer is Runtal

Thanks, this is interesting. They claim to offer a replacement for "aluminum baseboards and cast iron radiators". Their products are made of welded steel. I don't think, that's as good as cast iron baseboard. Their claim to replace radiators is, probably, based not on performance, but on aesthetics. you can google steam radiators and get some answers

No, steam is too hot  we want hot (or warm) water. The same question on a different forum has, actually, produced some intelligent answers.

I think, we'll go either with Burnham or Governale. Thanks, all.

Dufus,

I understand what you are saying about the thermal mass of the material, I'm just not sure it's something that is worth the hassle of installing cast iron baseboards - which I realize was never the question in the first place.

It seems to me that if you wanted to reduce temp fluctuations, you could accomplish that with a water storage tank that you circulated rather than adding the thermal mass to the baseboards themselves. Doing it that way would also give you the option to control the thermal mass (shut down the water) in order to avoid over-shooting temp set - points when the weather is more mild.

I would also think that the amount of radiant heat would be a function of the temperature of the water/steam as well.

I can understand convection. I'm just not sold on the cast iron baseboards.

Jake, this is a good point, but the plumber insists, water tank is "a thing of the past" and that efficient systems don't let the heated medium (water) "just sit there". I can understand convection. I'm just not sold on the cast iron baseboards.

Where I grew up (Kyiv, Ukraine) heat was done by hot water running through cast iron radiators (usually  hanging on the wall, rather than standing)  and we never had problems like I've had in the years of living in rental apartments here: jumping temperatures, dry air, heating elements bent out of shape, etc. So I want my house to be more like what I used to live in :) Except, I'm told, cast iron baseboards are even better, than radiators, so that's what it is coming down to.

Thanks! Yours,
doofus