Moving a heating register?

We're putting a sub-floor into a basement room, and the wall-mounted registers need to be moved up about 3". I'm assuming that this is pretty much a standard plumbing task; just drain the system, cut the pipe, solder in a couple of little jogs to move it up, and re-fill the system. However, I'm not all that familiar with HVAC stuff.
Questions:
1. Is draining the system a big deal? Any caveats? 2. While I've got the system drained, is there any maintenance stuff I should be doing? 3. Is there any problem from a circulation standpoint with having a couple of 90 degree bends in the middle of the system? 4. If I screw it up, what are the consequences of running a furnace with no water in the system? I'm assuming the furnace is smart enough to not self destruct if there's no water in there.
Thanks!
-Tim
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Well....

However,
You will need to get all the air back out of the system.

None that I can think of....

couple
Two additional 90, providing they are the same diameter as the origional ones, shouldn't be a problem.

no
Yes, it may self destruct. If you dry fire the boiler, you could burn your house down.
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I have yet to find any bleeder valves anywhere in the system. Any ideas? Or have I just not looked hard enough?

with
self
your
Interesting - you'd think there'd be safety features like that built in. If a heating pipe leaked while the boiler was running, this could happen pretty easily.
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Sorry, but I can't see it from here...

If
pretty
Yep, you're right. Some installers include some safety cut-offs and some manufacturers do. BUT, not all of them do stuff how it's supposed to be done....
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ideas?
Dammit! With the vast power of the internet, you can't see into my house? :) What I meant (and what I should have asked) is:
Is it likely that there are no bleeder valves in my system?
Second question - is anyone aware of a general "understanding all that scary HVAC stuff in your basement for dummies" kind of resource, either in print or on the web?
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Oh, boy....

Do I want to see into your house?

There 'should' be. I looked at a system a couple of weeks ago that had no way to bleed the system or to power purge it. The HO's were not happy with the system as it made a lot of noise as the air mixed with the water made it's way around. It seems the former owner had the boiler replaced and the hacks that did it had no idea what to do.

scary
Certainly is. Go to the tab 'Plain English Books' on this page http://www.heatinghelp.com/shopcart /
The entire site (www.heatinghelp.com) is a great one....
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Your furance should have a protective circuit that shuts the furance off if the water pressure drops below a certain level (mine does). Check you manual. Running the furance without water will most likely lead to cracking the heat exchanger and ruining the furnance.
Bleeder valves are usually place at the highest point in the circuit. Keep looking. If not, install them when you have the system drained. There might also be a vavle and drain combination near the circulation pumps whick allow for bleeding the system.

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Hi Philip, hope you are having a nice day
On 12-Oct-04 At About 00:57:48, Philip wrote to All Subject: Re: Moving a heating register?
P> From: snipped-for-privacy@hotmail.com (Philip)
P> Your furance should have a protective circuit that shuts the furance P> off if the water pressure drops below a certain level (mine does).
if it heats water for heating it is a boiler not a furnace. a low water cut off works on water level not pressure. Most of the newer ones are electronic so when the water level drops below the sensor it shuts off the burner.
-=> HvacTech2 <=-
.. "I bought instant water but I don't know what to add..."- s.w.
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<< 3. Is there any problem from a circulation standpoint with having a couple of 90 degree bends in the middle of the system? >>
Not really, but if you use a pair of 45 degree bends insteae of each 90, the flow will be better and perhaps bleeding air might happen more readily. HTH
Joe
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