Precautions When Shutting Off Water?? (Hydronic Heating)

I have a friend who lives some distance from me. He needs to repair a Delta tub faucet and apparently has no stop capabilities on the valve itself and no valves to isolate that part of the plumbing. Water will have to be shut off at the inlet to the house. He has a hydronic heating system and an oil burner. Are there any special precautions that need to be taken before stopping the water? I am afraid that air will enter the hydronic system. (I know sometimes purging can be difficult, especially by one with little experience.) Your suggestions would be much appreciated. Thank you! Frank
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frank1492 wrote:

I can think of a few items.
1) On the heating system, locate the shutoff supplying water to the boiler. Close it. You can turn off power to the heating system but it's not really necessary.
2) Close Main supply valve.
3) Open faucets (H/C) on highest level of house.
4) Open faucets on lowest level to drain entire system.
Now it should be safe to disassemble the tub faucet. If the system isn't completely drained first, there is danger of water running inside the bath wall when the tub control is taken apart.
May be more than he wants to get into now, but this would be a good time to install shutoffs for the tub or at least that whole branch.
When re-starting, leave faucets open. Slowly open Main valve and let all the air escape from faucets. Then close faucets and allow pressure to build. Check every place you can for leaks.
Now open the shutoff valve for the boiler water supply. No air should get into boiler/system and the boiler pressure should be exactly where it was before.
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Thanks Jim for all your excellent help. I have passed this along to my friend. One thing I wonder about: Won't there always be some air in the pipe to the boiler valve, that will get "pushed" into the boiler when the water is restarted? I know there is a float valve designed to eliminate the air to a degree, but I had all kinds of trouble until I installed a Spirovent. Frank

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frank1492 wrote:

I honestly don't think I would worry about it.
You could maybe bleed off water (somehow) at the end of the boiler supply line to get rid of any entrapped air but it could be difficult to do.
Jim
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In the old days didn't they use tanks with air bubbles in them as a reservoir to keep positive water pressure in the system? Now they are replaced with tiny tanks with an air membrane inside which is better because eventually the bubble in the large tank was absorbed by the water and you had to drain the tank to let some air in.

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I mentioned a Spirovent. I don't know if either of you guys have ever heard to these, but when you are sick of air problems, they are the ultimate answer. http://www.spirotherm.com/air /
On Tue, 14 Feb 2006 04:04:29 GMT, "Art"

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dissolved into the fresh water supply is air as well, that's another thing to check for air annually before each heating season.
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