Trouble Bleeding Air from System


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Old 12-19-09, 12:05 PM
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Trouble Bleeding Air from System

I have taken a stab at bleeding the air from from baseboard heating system due to what appears to be air in the second floor zone (lot's of noise when water begins to circulate). Following through the steps noted on another thread I thought it all went well but as soon as I started the system back up I immediately heard water trickling through the pipes which to me says "even more air in the pipes than before." The second floor zone makes even more noise so I must be doing something wrong.

My system is a Weil McClain gas fired boiler, 2 zones (first and second floor) with an Amtrol indirect fired water heater.

Here's what I did to bleed the system:

1. Turned system off.
2. Attached hose to second floor zone hose bib.
3. Closed valve below hose bib to boiler. To be safe I also closed the zone 1 and the water heater valve (Amtrol unit heated by boiler).
4. Opened the zone 2 hose bib and let the water flow out into laundry sink for about 10 minutes. Interestingly enough, there was rusty water starting to appear at the end of this process. The fill valve on our system is always open (I assume because the water heater needs it source) so as soon as I started draining/bleeding the system, makeup water began entering the system.
5. Closed zone 2 hose bib and let the system top off. Opened up all valves to boiler and water heater. The pressure was up about 5 psi more than when I started and topped off at about 28 psi.

Once I started the system up again I heard much more noise in the pipes than when I started. What am I doing wrong here?? Should the system be turned off? Am I shortcircuiting the process by way of wrong valve usage?

Attached is a link to some photos of my system.

Boiler pictures by TomH67 - Photobucket

Any help would be greatly appreciated.

Tom
 
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Old 12-19-09, 12:32 PM
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Originally Posted by NorthShoreTom View Post
The pressure was up about 5 psi more than when I started and topped off at about 28 psi.
28 psi is too high for the hot temp with a 2-storey house.

There may be more than one problem going on here.

First, an automatic fill valve might not be able to keep up if you are draining the system for 10 minutes, possibly sucking air into the system - unless somebody is cracking open the fast-fill lever at the same time. And all that water you drained will bring in lots of makeup water, full of disolved air. Do you have bleeder valves on your heat emitters (e.g., baseboards)? Bleed air there and save the power purging until the bleeder valves don't do the job..

I see two air removal devices - one above the boiler and one above the expansion tank. It looks like maybe the caps are on and possibly tightened? They need to be loose or off so air can be eliminated.

The next step, after venting the bleeder valves, is to slowly drain the system until the hot pressure is about 15-18 psi (or room temp pressure is about 12 psi).
 
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Old 12-19-09, 02:18 PM
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i suggest a simpler procedure:
just open each bleeder, there may be many-one at each radiator, and leave it opentill all air out and only water flows(keep rag handy)
 
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Old 12-19-09, 04:27 PM
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In the olden days some of us used to say "Never trust anyone over 30"... now that I'm well over 30, I say "Never trust a pressure gauge over 30" !

I hate gauges.

Mike doesn't know I have a time machine, and can travel back in time to post things before he asks!

 

Last edited by NJT; 12-19-09 at 04:54 PM.
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Old 12-19-09, 04:43 PM
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Two pressure gauges are better than one. Trooper, maybe you could repost your hose-connected pressure gauge contraption.
 
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Old 12-19-09, 05:05 PM
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OK, thanks - that was what I was referring to. I built mine with a 2.5", 0-30 psi gauge from Omega Engineering. That range, or smaller, gives best resolution. Also, the larger diameter gauges give more resolution.
 
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Old 12-19-09, 08:35 PM
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Thanks for the feedback everyone. I did some more poking around this afternoon after posting my question and discovered a couple things. Whenever our house was converted from steam radiators to baseboard (before we bought the house) the contractor did not install any bleeders on the fin tube so I am out of luck there.

I was under the impression that I didn't have a fast fill lever but after more looking, I noticed that there is a small brass lever on the fitting (pressure regulator?) just beyond the backflow preventer. When lifted the water flows freely. I assume I just discovered the fast fill lever? I'll need to try using that the next time I attempt this bleed. Could be the cause of much of the air intake.

Just for kicks I checked the relief valve near the rear of the boiler. It's rated for 30psi FWIW. I lifted the lever and drained some water/pressure off. Interestingly enough the water continued to drain long after I set the valve lever back in the normal position. This is all a bit foreign to me so I am not sure if this is normal or my valve is faulty. The pressure dropped down to about 20 PSI. About an hour later I checked again and sure enough if the pressure was not up to 28 psi again. I guess my next step will be to build myself one of these pressure guages to verify the accuracy of the guage on the boiler. I assume this guage would attached at the hose bob where I bleeding the air from?

Mike- The air removal devices you speak of has the black caps loose but the red cap is tight. I have to admit I was not sure what the color coding meant so I was not inclined to change them from their settings. Should I loosen both caps then?
 
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Old 12-20-09, 05:18 AM
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relief valve: this is a safety device, so that if the pressure in your system gets too high, it willrelease water and not have boiler explode.
as deposits collect, it may not reseal itself, and unless you can clean out the depostis, you might need to replace it. some poeple believe these valves should be replaced every 5 years or so.
 
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Old 12-20-09, 06:40 AM
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Headin' out to crank up the snow blower... 16" here...

You can also go to HD or Lowes and pick up one of these:



Notice that the gauge itself is too high pressure to give good resolution down at 10-15 PSI, but you can't really buy the fittings for the 10$ they get for these... so on the way home, stop by a pool supply, or a real plumbing supply and pick up a 30 or 50 PSI gauge and replace the one that came with the gauge.

Might wanna think about replacing that relief valve also, but if it stops dripping, it can wait till spring. It also might have just been the water in the pipe that was drippling out.

One thing you can try though... lift the handle all the way, and let it go and SNAP! shut. Sometimes that works... sometimes not...
 
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Old 12-20-09, 03:10 PM
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Here's a source for 30-psi gauges: Utility Gauges For Industrial and OEM Markets Dual psi/bar Scales

I bought the 2.5" model - but if I had to do it again, I'd probably pop for the 3" model (more resolution).

My Ace hardware has the barbed connectors to attach the gauge to a hose end. The hose displayed by Trooper looks to be about 12-18" long? Mine is about 5-6 ft long. That enables me to position the gauge right next to my boiler's gauge - so elevation differences are zero. (1 ft WC = 0.5 psi, approx).
 
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Old 12-20-09, 05:37 PM
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The hose displayed by Trooper looks to be about 12-18" long?
Maybe not quite that long... it's a cut off end from an old warshin' machine hose.
 
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Old 12-21-09, 07:30 AM
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So yesterday I bled the system again and used the fast fill lever this time. I also opened both the red and black caps on the air removal fittings on the system. This helped quite a bit. I still get loud clicking or popping on the vertical riser when the water starts to circulate up to the second floor but no more tricking in the pipes. I have to wonder if this is just the expansion of the pipe making most of this noise.

No matter method I used to let pressure off the system, pressure relief of bleeder valve, the pressure makes it's way back to 28 psi +/-. That said, I just ordered the 3 1/2" gauge from Omega. A little project for the Christmas vacation! Thanks for the info. I'll post my findings once I have them.
 
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Old 12-21-09, 11:02 AM
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And it takes 30 or so minutes for the gauge to creep back up to 28 psi? If so, it doesn't sound like a bad gauge to me.

The 3.5" Omega gauges have back (rather than lower) fittings. Should be fine, but watch out that you don't kink the hose and get an invalid reading.
 
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Old 12-29-09, 06:49 AM
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Originally Posted by NJ Trooper View Post
You can also go to HD or Lowes and pick up one of these:



Notice that the gauge itself is too high pressure to give good resolution down at 10-15 PSI, but you can't really buy the fittings for the 10$ they get for these... so on the way home, stop by a pool supply, or a real plumbing supply and pick up a 30 or 50 PSI gauge and replace the one that came with the gauge.

Might wanna think about replacing that relief valve also, but if it stops dripping, it can wait till spring. It also might have just been the water in the pipe that was drippling out.

One thing you can try though... lift the handle all the way, and let it go and SNAP! shut. Sometimes that works... sometimes not...
UPDATE: I took my new 30 PSI guage from Omega and connected it to the to fittings on the one from HD as suggested (I skipped adding additional hose length). I took 2 readings; one from the bottom boiler drain and another from the zone drain which is about 30" above it. The pressure readings were 14.5 psi and 14 psi, Edit: 17.5 psi @ bolier drain while running- ~180 degrees)respectively. Meanwhile the guage on the boiler was still registering at about 24 psi. Looks like your hunches were correct folks-- inaccurate system guage!

Interesting enough, I have noticed water has blown out from the pressure relief valve at one point or another. Looks to be a fair amount of water. I threw a bucket under it to track how much comes out from this point forward. Maybe it was the valve leaking since I loosened any deposits or maybe it's time to replace it all together. It would seem that this is not actually hitting it's 30 psi limit based on my current readings.

Lastly, the pipes STILL make a whole lot of ticking and snapping as the water starts to circulate. It's in the same spot every time on one of the vertical risers. Long story short, I may not have solved the original thing I set out to do after all this. Ugh.
 

Last edited by NorthShoreTom; 12-29-09 at 07:59 AM. Reason: Additional info
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Old 12-29-09, 02:28 PM
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OK, that's good... you can't ask for much better than that. The fact that you only have a few PSI rise from cold to hot tells us that you expansion tank is probably doing it's job.

I still get loud clicking or popping on the vertical riser when the water starts to circulate up to the second floor but no more tricking in the pipes. I have to wonder if this is just the expansion of the pipe making most of this noise.
It sounds as though you have most of the air out of the system now... that's good too...

Is there a brand name / model number on the air vent above the expansion tank? I can't recall ever seeing one that had two caps on it?

'Ticking/clicking' and 'popping' noises can be from expansion. Some noises of this type can also come from the 'flow control' valves that I see in one of your pics...

Often the holes they drill to pass pipes through are not big enough. If the pipe is touching a piece of wood where it passes through, it will make noise when it expands. If you can localize where the noise is coming from, sometimes you can spray silicone spray on the wood and pipe... but be careful, because that stuff will stain finishes and furnishings! Plastic shims cut from a milk bottle can sometimes be slipped around the pipes and stop the noise. The main thing, and the hardest part, is finding the source of the noise, because it will 'telegraph' down the pipe.
 
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Old 12-30-09, 04:41 PM
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Originally Posted by NJ Trooper View Post

Is there a brand name / model number on the air vent above the expansion tank? I can't recall ever seeing one that had two caps on it?
The vent is by Watts.
Watts: DuoVent | High Capacity Air Vents with Manual Vent Feature
I did some digging on their website to see what the deal with the 2 caps were all about. The back cap is for automatic venting and should be loosened 2 turns. The red is for manual venting. I removed it all together when I was trying to get the air out. I have no idea is it worked or not but there you have it.

I was starting to consider that the noises were from expansion as well. I have a sense of where is starts although some of the sounds are in the wall but I am going to experiment and see what I can find.

Appreciate all your advice so far!
 
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Old 12-30-09, 06:24 PM
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The red is for manual venting. I removed it all together when I was trying to get the air out. I have no idea is it worked or not but there you have it.
Thanks for the info on the DuoVent...

You removed the red cap and didn't have a fountain of water spraying all over ? If so, I think something is plugged up in there. From what I can see in the drawings of the vents, that one should spew water (after the air) if the cap is taken off!
 
 

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