My apologies for speaking out and I hope this isn't taken the wrong way,
but this post and the answer are very simple. You guys are complicating
everything.

"I'm guessing you have a one pipe steam system. If you 'don't vent'
the
radiator (and it is a one-pipe system), it won't heat.

They do make adjustable vents for one pipe system. Ask at the Wall.
http://forums.invision.net/index.cfm?CFApp=2"

The idea is that he doesn't want certain radiators to heat to their
full capacity. Therefore he doesn't need self-bleeding valves.

"Don't the radiators have shut off valves. Do you mean turning off the
water at the boiler, that is circulation and some is needed so pipes
do
not freeze. What you state makes no sense."

He doesn't want them shut off, he wants to regulate their heat ouput.

"There shouldn't be. If your system is constantly taking in fresh,
(dissolved) oxygen-laden water, the will be corrosion. I'd worry more
about
the boiler than the radiators."

You have no leak, no fresh water entering the system beyond what would
enter it if there was no air in the radiators. The boiler is not
affected in any way

"I kinda get your point, but I'm looking deeper. If your system is set
up
correctly, there should never be any air in your system."

There shouldn't be any air in the system but to accomplish that, you
have to bleed the radiators manually periodically or have self
bleeders. He doesn't want it setup correctly. He wants to utilize the
fact that air is trapped in the radiators to regulate their heat
output.


"Well, that has to do with the make up water. If you have a leak and
air is
getting in, that means fresh, oxygenated water is getting in the
system.
That fresh water will cause corrosion."

Again, there is no leak, so no more fresh water will enter the system
becuase of air in the radiators than would enetr it if the air were
replaced by water.


" This should prevent the water from circulating properly in the
radiator. But does this mean that all the radiators that follow in that
zone will also not heat up
properly?"

The water flows into and out of the radiator at the bottom. The air
lock is at the top. As long as there is a few inches of water in the
radiator, water will continue to flow through to the following
radiators.

What you want to do is a very simple comcept. It has nothing to do with
the boiler or how many zones or fresh water entering the system. It's
good advise for a properly functioning system. Ignore it. A
disadvantage of hot water radiators is that they have to be bled
periodically. You want to use that disadvantage to your advantage and
regulate heat output. It is a very good idea. It does work and you will
not harm your system as explained above. In the real world, many people
never bleed their radiators and never know the difference. It's better
to regulate heat output with air in the radiator (harmless) than to
have a properly functioning system and and a few windows open to let
excess heat out.

Think about it. Sewer lines are cast iron. Radiators are cast iron. For
all intents and purposes, they don't corrode.


--
hwm54112
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