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Old 02-16-2011, 11:05 AM   #1
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Air in my boiler system


Hello,

I've been largely unsuccessful in fully bleeding out a 4-zone boiler system in my house. I just had a section of piping replaced (cooper to non-oxygen PEX), and shut down the boiler during this transition. I also drained the water down quite a bit and shut off the corresponding zone where the replacement took place, during the replacement.

When I re-entered water into the system, there was a TON of air in the pipes. I started bleeding (spigot to garden hose style, each zone has a spigot where water returns to the boiler) the two downstairs-related zones, then followed with the two upstairs-related zones. I had (what seemed) to be all the air out of the system. Not 30 minutes later did I hear more gurgling system-wide, but much more/louder upstairs. I have a few hypotheses, but I'd like some help on this:

1) Is the problem air in the fresh water into the system? (the main water WAS shut off for a period of time to the house, for another repair, and obvious sputtering at other faucets in the house occurred after it was turned back on).

2) Could there actually be a leak in the system now? I would think this is unlikely, since the copper->PEX replacement area shows no leaking...

3) Is it an expansion tank issue?

Thanks!

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Old 02-16-2011, 06:00 PM   #2
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Air in my boiler system


How are you filling the system? You should have your fill valve set at the psi you need. You need to go to the highest points for each zone and open up the vents. Your air vent in the basement will get most of the air but the highest point is your best bet. As you let out more air you should let in more water.

You need to have water coming out of the vents upstairs.

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Old 02-17-2011, 05:57 AM   #3
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Air in my boiler system


When I purge the air from a boiler system. Each zone takes as long as it takes. Some as quick as 5 minutes, others may be 10 minutes or more.

Does your system have an auto air vent. Do your baseboards have air vents on them? Are you sure that the fresh water entered through the boiler, then went through the full heating loop and back to your purge/drain valve?
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Old 02-17-2011, 09:10 AM   #4
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Air in my boiler system


Hi guys, thanks for the replies.

1) Yes, the fresh fill valve does have PSI on it. I am able to open each zone's spigot and also balance the pressure of the new water into the system, keeping a steady 15-20psi while bleeding.

2) There is only one baseboard (upstairs, furthest from the boiler) that has a valve for purging air. I've gone through countless bowls-full of water trying to get air out of there.

It seems the air in the system has migrated to the pipeline where the fresh water comes in. The air from the two upstairs zones (as of last night) is virtually non-existent (system PSI holding steady at 18), but when I turn on the fresh water valve, I get the loud groaning noise. I'm not sure on the terminology, but there's a pipe that is open to the floor, just before the valve that lets the fresh water into the boiler system. The new water from the supply valve just spews out of that now without any water entering the system. Is there now a hydronic block in this section?

Additionally, it seems odd to me that after the main water to my house was shut off and turned back on after the project was complete that 48 hours later I'm still getting sputtering through many faucets in the house.
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Old 02-17-2011, 03:15 PM   #5
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Air in my boiler system


Quote:
(system PSI holding steady at 18), but when I turn on the fresh water valve, I get the loud groaning noise. I'm not sure on the terminology, but there's a pipe that is open to the floor, just before the valve that lets the fresh water into the boiler system. The new water from the supply valve just spews out of that now without any water entering the system. Is there now a hydronic block in this section?
Ayuh,... How 'bout some pictures of the near boiler plumbing,..??
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Additionally, it seems odd to me that after the main water to my house was shut off and turned back on after the project was complete that 48 hours later I'm still getting sputtering through many faucets in the house.
Have ya left 'em Run for awhile to purge 'em,..??
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Old 02-17-2011, 03:19 PM   #6
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Air in my boiler system


Was thinking of doing that anyway, Bondo. Will post pictures later this evening.
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Old 02-17-2011, 06:08 PM   #7
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Air in my boiler system


That valve is a vented back flow preventer. Either its bad, or its doing its job, and the boiler pressure is higher then the city water pressure coming to it.
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Old 02-17-2011, 06:45 PM   #8
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Air in my boiler system


Okay, here's two pictures:

IMG 039 - This shows the piping for adding fresh water to the system. The yellow arrow denotes the pipe inbound (from a valve out of the picture above this point), and the red arrow is the pipe where I'm getting discharge and water isn't entering the system. The white, circular dial in the background is my PSI gauge. Currently the PSI is 18. Of note, the yellow handle valve also in the picture allows the fresh water into the system (yes, separate from the valve previously mentioned)

IMG 040 - Just shows the spigots and piping of all 4 zones for reference.

I guess at this point the status quo is there's still air in the system, but its seemed to have migrated to close to where fresh water enters. Ive never had an issue adding/subtracting water before, but now when I allow fresh water it, it goes straight to discharge.
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Old 02-17-2011, 07:51 PM   #9
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Air in my boiler system


I see there is a valve closed after the BFP but I do not see the boiler feeder. Is the feeder on the boiler side of the BFP out of view or the inlet side?
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Old 02-17-2011, 07:52 PM   #10
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Where is the shut off valve after the purge valves.
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Old 02-17-2011, 09:08 PM   #11
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Air in my boiler system


JohnH/BeenThere, I certainly appreciate your guy's input, but you'll have to forgive me on the terminology. I have a working understanding of how the system operates, but not what each parts are called.

JohnH, if I'm understanding you correctly, the feeder line to the boiler is essentially at the bottom of this picture. You can just see the corner of the boiler in the lower left here.

Beenthere, not sure on the shutoff valve your referencing.

If I'm still not providing enough info, Im happy to keep snapping away.
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Old 02-18-2011, 09:57 PM   #12
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Air in my boiler system


I see a closed valve after (boiler side) the BFP (Back flow preventer) IE were the water is discharging. Is there a automatic water feeder feeder before te BFP or another closed hand valve?
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Old 02-18-2011, 11:44 PM   #13
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Quote:
Originally Posted by JohnH1 View Post
I see a closed valve after (boiler side) the BFP (Back flow preventer) IE were the water is discharging. Is there a automatic water feeder feeder before te BFP or another closed hand valve?
Yes, there's another valve above the yellow arrow in the 1st picture I posted. It is not automatic, rather identical valve to the yellow valve in the most recent picture. To reiterate, there's two valves: one higher up near the ceiling in the room where the pipe from the main comes into the room. That's ultimately the governor of fresh water into the system. The other valve is where you describe, to the boiler side of the BFP.

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