# Weil Mclain Boiler air in system



## manning01 (Sep 28, 2007)

I have a VHE-4 Weil Mclain Boiler installed in 1986 and I have alot of air in the system it sounds like a stoney brook when it's running. Also I get periodically a 1-2 load clunking/bang noise coming from it when it's running but not all the time. It's in our crawl space so I'm not there when it happens. I just changed out the tridicator gauge since it was totally inop and unreadable. The temp is okay and the pressure holds and never reaches max pressure. Also the expansion tank sounds hollow on the far end and the auto vent is a amtrol auto vent around 2-3 years old and it's located on top of the boiler, ther eis no other auto vents in the system. The auto water fill valve is also around 3 years old and seems to work just fine. I have tried to bleed the system by opening manually each zone seperately to bleed the air out one zone at a time, but I'm not getting it all out. I also open the water auto fill valve while doing this and run the water at a slow pace for about 1/2 hour on each zone. But it's still there and I assume the bang/clunk is from all that air in the system when the zone valve closes they are Honeywell zone valves. Also the local parts place gave me a new auto air vent made by maid o mist but not sure if I really need it when I got the new gauge. It just seems so cheaply made compaired to the Amptrol one installed on top of the boiler. One thing I was told was to close the red valve closest to the zone valves, would that be my mistake. I wanted to attach a picture but I can't get it down to the size limit they have here. I can email it to anyone if that will help on seeing the layout. Any help on the proper way to getting this air out of the sytem is greatly appreciated, thanks.


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## redline (Mar 5, 2006)

Was there air in the system prior to changing the gauge?

Was the whole system drained when the gauge was changed?

How much PSI is on the system?

How many zones?

How many stories/levels does the heating system consist of? (how many stories to the house? --- 1,2,3..)


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## manning01 (Sep 28, 2007)

redline said:


> Was there air in the system prior to changing the gauge?
> Yes
> Was the whole system drained when the gauge was changed?
> No I only made sure it was cool and just drained the boiler itself
> ...


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## redline (Mar 5, 2006)

Do you have slant fin baseboard or another style?


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## manning01 (Sep 28, 2007)

Yes the baseboards are normal copper lines and aluminum fin design, I don't have radiators this is a system installed in 1986. There are no auto air relief vents on any of the baseboards that I have found not even a bleeder screw so it's totally enclosed system. So I can only find the one air vent and it the auto vent right on top of the boiler made by amptrol and the cap is turned out 1 full turn to let the air out. If I turn off the red handle right near the zone valves and I manually open each zone seperately while the boiler is off purge the lines I have a hose attached to the line and I have a drain on the floor so no problem letting it run for along time to get the air out that should do it right? But do I need to do it longer then 30 minutes per zone? I do have the auto fill water valve manually open while doing this to get this process to go faster.


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## redline (Mar 5, 2006)

Are you handy enough to solder a bleeder on the first floor?


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## manning01 (Sep 28, 2007)

Yes I can do that but can't I just do it down there in the crawl space like the HVAC guy has done in the past? If I can save from opening up the sytem again I'd like to do that, plus saving more money.


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## redline (Mar 5, 2006)

It should not take more then 10 minutes to unsolder an elbow on one of the baseboard units and then solder on a new elbow that has a bleeder.

Will save you time if the system needs service in the future and needs to be bleed.


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## manning01 (Sep 28, 2007)

Okay I'll try that this next weekend when I have time to get it done, I'll put one on each zone. I did swap out the auto vent on the boiler and did a pressure check on the expansion tank it was only 8 psi. So since I drained the boiler to change out the auto vent with the pressure off I pumped it up to 12 psi and tightened the valve core it was loose. I refilled the boiler and purged the zones one by one "cold". Then I opened the auto vent cap and fired it up, there is still some air but much better. I assume as it runs in the fall the auto vent will get the air out over a few weeks when it going alot. I do notice there is no more banging coming from the boiler I don't know if it was between the air in the lines and the expansion tank being low on air. Also the boiler does run at around 25 psi running and runs up to 175 deg shuts down and doesn't turn back on till it drops to 165 deg I assume this is all good. thanks for all you help I'll let you know how the bleeder job goes.


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## redline (Mar 5, 2006)

Sounds like you have eliminated a few minor problems that would have contribute to the initial problem.

You are on the right track.

The 25 psi seems a little high.


"... and runs up to 175 deg shuts down and doesn't turn back on till it drops to 165 deg I assume this is all good."

What do you mean that it shuts down? Is just the burner shutting down or is the whole boiler shutting down?


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## manning01 (Sep 28, 2007)

Just the burner shuts down at 175 deg the circulator continue to runs and the burner turns back on at 165 deg. Yes it sounds like the pressure is running alittle high not sure what to do to get it down. The relief valve works when it should I found that out when purging the lines. If I left the auto feed valve open and the drain hose off the pressure would build up to the max pressure 30 psi for the valve and it would release. Other wise I don't see any evidence that it has released water pressure any other time in the past except when I made it vent.


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## redline (Mar 5, 2006)

The auto feed should have an adjustment on it. Unless there is a pressure regulator. Adjust the income water pressure to the boiler so it is lower.


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