Why are radiators made of cast iron

[Sam Takoy]

Hi,

Why is cast iron a good material for radiators? Why not another metal? Would certainly make them a little lighter and easier to deal with.

Thanks in advance,

Sam

[Lefty]

Cheap, durable.

'nuff said?

[David Nebenzahl]

On 3/7/2010 8:30 PM Sam Takoy spake thus:

Aluminum might be better, but wasn't around when cast-iron radiators were first made. Iron is an excellent metal for casting and conducts heat well (and is less expensive than other metals, like copper, that are better conductors).

[DD_BobK]

In no particular order........ cheap, decent heat transfer characteristics, relatively good corrosion resistance, low tech manufacturing methods

cheers Bob

[krw]

They are. Newer homes, with hydronic heat, have copper or copper/aluminum baseboards. Cast iron baseboards have become *expensive* (and a waste of money).

[The Daring Dufas]

I would imagine one benefit of a heavy cast iron radiator would be the mass of metal will hold heat and release it over a long period of time. I also think that a copper or aluminum radiator of similar thickness would be prohibitively expensive.

TDD

[Doug Miller]

Finally, a correct answer.

[The Daring Dufas]

I guess majoring in physics wasn't useless after all. *snicker*

TDD

[EXT]

I don't know that ALL radiators are made of cast iron, mostly old radiators made around the time of WWII and earlier were cast iron. These days many are fined tubes, or other materials. The ones used in Europe seem to be made from pressed sheet steel.

[Doug Miller]

Guess not. But, yes, you hit the nail on the head. The principal advantage of cast iron radiators is that they retain heat very well, which provides a much more even heat than the aluminum fin-tube radiators do.

[willshak]

The disadvantages are that they are big and ugly and get very hot (don't allow toddlers around them). They have enclosures especially built for them which also helps with the ugly part. Another advantage is you don't need a humidifier, just put a pan of water on top of them. I was brought up in homes with steam radiators in NYC.

[HeyBub]

Because straw isn't very durable?

[The Daring Dufas]

When I was a kid and an inmate at the Catholic Parochial Gulag back in the middle of the last century, the building had radiators with hissing contraptions on the top side that reminded me of the valve on a pressure cooker. If I remember right, there was steam coming out of the thing that could very well have contributed to keeping the humidity up in the building.

TDD

[The Daring Dufas]

I've read about the Scandinavian or Finnish style fireplaces that have a huge mass of masonry which does the same darn thing. I've always thought that if I were to ever build a home, I would want such a fireplace. Add a bit of hysteresis to the heating cycle and keep things comfortable.

TDD

[Tony]

The aluminum fin baseboard "radiators" are actually "convectors", not radiators. Most of the heat from them is cold air going in the bottom and warm air coming out the top, known as a "convection current". If you sit in front, 2 feet away, you won't feel the heat on your body like you do if you sit in front of a radiator. Radiators also have convection currents but not nearly the same as a convector.

[Tony]

It's called "steam heat".

[Tony]

The only problem is they take a long time before putting out any real heat. Maybe a fire all day until the mass of masonry gets hot. The more mass, the longer it will take. Also the more mass, the more even the heating will be.

[The Daring Dufas]

I think the nuns were trying to cook us.

TDD

[mike]

Agreed. I don't like heating systems with a large lag factor. I want instant heat when I want heat, and when things are warm enough, I don't want the system to keep pumping out heat.

[Doug Miller]

Horse-puckey. They don't get any hotter than the water that's circulated through them.

Some do. Many don't.

Ahh, that explains your misconceptions. You're apparently unaware that many homes are heated by hot water, not steam.