Why are radiators made of cast iron

Mar 08, 2010 114 Replies

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.

Except that the systems aren't sealed. The oxygen is never "used up".

Really. Aluminum oxide is impervious to oxygen. Aluminum will only oxidize on the surface. Scratch a hunk of aluminum and it'll get shiny, for a couple of minutes.

I had a nail hole turn green and leak. The nail was on the inside. :-(

Most are, in fact, closed systems.

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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.

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.

Wrong. Most hydronic systems have automatic fill valves, mostly because they need them.

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When you cant explain something, use a personal attack. Thank you for showing your true self.

Keeping them open all the time is the way things used to be done. Accepted best practice now is to keep them closed except when it's actually necessary to add water to the system -- which is fairly rare, in a well-maintained system. If you need to keep adding water to a hydronic system, you have a leak somewhere.

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There's a lot of people here can't grasp the fact that oxygen in the water is not the problem. Dissimilar metals are the problem. You have in effect a battery. Electric currents are circulating in the pipework. Apart from adding anti corrosion chemicals, the other method of control is to install a "sacrificial anode", usually made of magnesium. This rots away instead of the pipe system.

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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.

The leak would show. Nope. Fill valves need to be left open to insure the proper pressure on the system.

That simply isn't true. Once the system is filled and pressurized, it will remain at that pressure when the fill valve is closed -- unless there's a leak.

If there's no air in the system, there's nothing to bleed.

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