Why are radiators made of cast iron

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*And* cool off, which means that the temperature changes much more gradually.
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On Thu, 11 Mar 2010 04:23:18 GMT, snipped-for-privacy@milmac.com (Doug Miller) wrote:

Sure, thermodynamics requires things to be symmetrical, that way. ;-) However, the time ramping up and down are inefficient. Waiting for the ramp up, your cold. On the way down, you've wasted that heat. Nothing for nothing.
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Perhaps you live someplace where you turn your heat on and off every day. Where I live, it's cold enough in the winter that we leave the heating system on all the time. We *want* those radiators to stay warm.
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On Thu, 11 Mar 2010 23:29:33 GMT, snipped-for-privacy@milmac.com (Doug Miller) wrote:

When we lived in VT we changed it several times a day, four times automatically and another one or two manually. Here we have heat pumps, so no fiddling with the thermostat.

I like sleeping in a cold house and reasonable during the day (VT house 59night/64day with a boost to 68F in the evening) .
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Where is the heat wasted? If the house is constantly losing heat on a cold day, the heat from the radiator is just helping to maintain it for a longer time between cycles. The perfect system it to balance the heat loss with the heat makeup of the radiators to maintain a perfect temperature all the time.
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Heat loss is proportional to the temperature difference. If you leave the difference higher, longer, the loss is more than it would have been if the temperature came down more quickly. Nothing for nothing.

The higher the temperature (difference) the higher the loss.
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OK, that is true and complies with the laws of physics. But where is the waste? If I keep my house at 70 with copper, I use the same heat as keeping my house at 70 with cast iron, cast aluminum, or hollow chicken bones. 70 degrees is 70 degrees and it takes the same Btu to maintain that temperature over outside ambient no matter the source.
Only way you'd have waste from the higher heat loss is if the temperature inside overshot the thermostat. That is the fault of system design or bad equipment, not the heat transfer material. Cast iron allows for a nice steady heat.
I don't see any loss.
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The loss arises through the overshoot. If you have a sytem that can exactly matches heat requirements its possible to make very significant savings.10-15% would be pretty typical.
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If you can absolutely keep the temperature constant, you're right, the material doesn't matter. Cast iron has no benefit, then, either. Symmetry.

If your temperature is perfectly constant cast iron does *not* "allow for a nice steady heat". It doesn't matter.

You're not seeing the whole picture. You've simplified the world until it doesn't matter and then claim that it does. <shrug>
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The benefit is that cast iron allows you to maintain the symmetry easier with thermal mass.

That has not been my experience. Heat source materials are only part of the system, you need a proper thermostat and water pumps too.

It was simple all along. You are trying to make a simple thing complex. How much heat loss is there if you overshoot the temperature by one degree? Given your insistence, you must have some numbers on this.
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Symmetry doesn't get "maintained", it *is*.

Your "experience" is wrong. Physics doesn't allow it.

YOU are evidently too simple to understand it. TANSTAAFL.
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When you cant explain something, use a personal attack. Thank you for showing your true self.
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You demonstrated your understanding of physics; simple. I just stated that fact. Sorry if what I say on the Usenet upsets you. Perhaps you should be somewhere else.
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snipped-for-privacy@att.bizzzzzzzzzzzz wrote:

This poor boy never heard sarcasm before.
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Poor dork can't read.
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Doug Miller wrote:

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.
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Nope. I this sense they're both "convectors". A "radiator" (without convection) wouldn't be at all efficient. The source temperature would have to be much too high.
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snipped-for-privacy@att.bizzzzzzzzzzzz wrote:

Yes, heating systems with radiators normally run at higher temps then convectors. Besides, Google is your friend. Do a search for "baseboard convectors".
Here is some more for you!
http://www.finehomebuilding.com/how-to/qa/baseboard-vs-radiator-heat.aspx
"A: Mark Eatherton, a plumbing and heating contractor in Denver, Colorado, replies: Radiators and baseboard convectors both depend on hot water as their heat source. The similarity stops there. As their name implies, radiators deliver heat in the form of radiant energy. In other words, the energy from a radiator travels through the air without heating the air until it strikes a solid object. The object is warmed, which in turn warms the surrounding air. A radiators primary function is affecting the mean radiant temperature, or the average surface temperature of the surfaces surrounding your body.
Older style upright cast-iron radiators are usually massive things, with most weighing a couple of hundred pounds. By their nature, they tend to radiate energy long after the heat has been shut off. In some cases, they can cause the room temperature to overshoot by a few degrees, but their overall comfort is superior to that of their cousins, the baseboard convectors. Radiators have some convective output, but it is minimal compared with their overall output potential."
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Do you believe every sloppily worded article on the Internet? The fact is that for a "radiator" to work the temperature difference would have to be *far* more than 100F. Think of an infrared heater. A boiler isn't going to do it. Convection is a *large* percentage of the heat transfer. Radiation is miniscule.

No they *CONVECT* heat long after they're shut off.

More sloppy wording to go with the sloppy thought.
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snipped-for-privacy@att.bizzzzzzzzzzzz wrote:

Yes, you are right and all the internet info is wrong. You are so much smarter than most of the world. You are incredible. Companies call their product "convectors" but you are so smart, you know they really aren't convectors, and all the silly people in the world call, and have called for 100 years, those heavy cast iron things that radiate heat "radiators" but you, you are so damn smart that you know more than the rest of the world. You know the cast iron things are really convectors. Damn, the whole world had it wrong all this time. Thank Gawd you came to teach us the truth!
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