Deliberately not venting a radiator?

Hi,
I am wondering if there are any adverse effects (like accelerated rust build up) associated with deliberately not venting some radiators in a hot water system. I would like to do this in order to decrease their heat output without having to install valves.
Thanks for any help.
RUsirius
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Cast iron doesn't rust
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hwm54112
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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

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It is a hot water system, not a steam system.
There are 3 circuits attached to the furnace. I would assume that the other radiators in the same circuit would still work even a one or two are not vented?!
So, there is no oxidation taking place in a cast iron radiator?
I think that not venting a couple of radiators is a more "elegant" solution then knitting a cover for them. :-)
Thanks for the responses.
RUsirius
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You keep saying vented, steam radiator systems are vented not hw heat. There are air bleed valves on Hw radiators to remove air , but once air is removed they are closed, and kept closed or water would pour out. 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.
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Mark, it depends on how his system is set up. If he has monoflow fittings, he can shut off individual rads. If it's a series circuit, he can't without effecting the entire loop/zone.
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Sorry for the confusion, I meant: NOT TO BLEED the hot water radiator in order to keep an air bubble in the radiator. 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?
My other concern is that this way there will be permanently air and some water in the radiator and thus I am afraid there might be more chance for oxidation.
The radiators only have simple shut off valves and are as far as I can tell in a series circuit. So I can't just shut one off without affecting the other radiators in the zone.
I hope this clarifies things.
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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.

Quite possibly.

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.

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HeatMan wrote:

Yes, but if I remove some water from the system, than I will get air into the radiators.....

In this case it has the same effect as if I simply would close the shutoff valve?
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the
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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.
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Thank you hwm54112 for speaking out and for your answer to my question. I hat just about given up on finding an answer through the forum. This doesn't mean that I don't appreciate all the effort by the other poster, I really do.
Thanks again to everybody
RUsirius
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In-line.

I've never heard of self-bleeding valves. Also, I guessed he had a steam system instead of a hot water system.

Fine.
Then where is the air coming from?

"If the system was installed correctly, there should never be any air in the system." What part of that statement don't you understand?

Read my last statement....

True.
If he needs to regulate heat output, get outdoor reset for the system. It'll save money too.

Yes they do.
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"If the system was installed correctly, there should never be any air i the system." What part of that statement don't you understand?
Heatman, you obviously don't know old heating systems and radiators You did not read the original post, nor my definitive answer and do no understand the concept of what faxemail123 is trying to do. Since answered his question to his satisfaction, I reply yet again to educat you a bit more only because you are a helpful though argumentativ person. What parts don't you understand?
A hot water system has air in the expansion tank. It has to be there If the expansion tank becomes water logged, the system will no function properly
A heating system gets air in it from the expansion tank, expansion an contraction of the water as it heats (air is released), air bubble introduced in make-up water and water originally used to fill system It doesn't have to have a leak. Air is introduced naturally. Moder baseboard heating systems don't typically need to be bled because the are basically just a water pipe with fins. There is no place for air t accumulate. Radiators have a very large space for air to accumulate. A such, radiators must be bled periodically and as such should hav valves in the top to let the air out. They are commonly known a bleeders. They are manually opened and closed with a "radiator key" t let air out. Self bleeders are valves which allow air out but no water. They typically were not used because of their additional expens (5 to 7 times as much as a manual valve) and because they frequentl stopped working and had to be replaced.
"Okay, this has gone too far for me to attempt to daignose over th 'net. I thnk you need to get someone into your house that knows hydroni systems."
He never had a problem to diagnose. Read the title of the post.
"If he needs to regulate heat output, get outdoor reset for th system. It'll save money too."
He doesn't need to regulate the heat output of the system, onl specific rooms,specific radiators, therefore resets for the syste aren't the answer.

For
Yes they do.
O.K. They corrode to the extent of getting a rusty coating on them Unless the cast iton is defective to begin with, they will no deteriorate to a point where servicability is affected. The cast iro sewer and cast iron radiators in my 90 year old house show no signs o deteriorization. Nor has any of the cast iron I've seen in some 5,00 houses been rendered unservicable. "For all intents and purposes"
Faxemail, glad I could help.
Heatman, it's been interesting. Keep up the good wor
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You've confused me. You have a hot water system and there are vents on the radiators? Vents that automatically open and close?

Three circuits, also known as zones?

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.

Agreed.... TRV's would work better than knitted covers.

Yer Welcome.

YesIAm
You may want to go to the Wall. http://forums.invision.net/index.cfm?CFApp=2
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Get someone to knit a cover for the ones that heat too much.
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