Bleeding Air Every Week

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  #1  
Old 12-15-18, 05:52 PM
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Bleeding Air Every Week

Hey Folks,

Problem:
  • I am bleeding upstairs baseboards weekly due to large amounts of air in system.
What I have:
  • Gas boiler
  • Baseboard heating on 2 floors, 3 zones total including domestic hot water tank.
  • Baseboards all have bleeder valves I can open to let air out.
  • No apparent leaks.
  • Boiler "reads" 20PSI.
  • Expansion tank feels warm on its half close to pipes, and cool to touch on the other side.
  • I am bleeding when system is on and hot, i can get it so the system is nice and quiet, until a week goes by and its back to garggly slushy air noise.
  • Boiler clanks and kettles(?) hard periodically, especially when system is turned on
Any suggestions or links to help me figure out how to keep air from entering my system?
 
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  #2  
Old 12-15-18, 06:28 PM
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A,
First off you said you have 3 zones total yet your pics show 4 pumps.

The procedure you use to bleed the system is everything in stopping air from returning.

First thing is you never bleed the system with the boiler and pump on. Everything must be shut off so you are using natural water pressure, not increased by the pump.

Next, you have purge valves on each return line that should be used and not the vents on the baseboards.

Close all valves on zones not being bled so the zone being worked on is isolated and the water pressure being fed into the system will only go the zone being bled.

Next to your extrol tank you have an auto feed valve with a lever, when raised bypasses the valve and lets you manually fill the boiler.

You want to get your pressure up to 25-28 PSI and the open the spigot to remove the air from the zone. You must keep the pressure to at least 25 PSI when doing this and let the water continue to drain until you get a good stead stream of only water coming out. Don't be in a rush. After all the air is out let it run for a good couple of minutes or so to make sure you got it all.

When your satisfied, close the spigot and shut off the feed and proceed to the next zone and repeat the procedure.

When you are all done you should still have your 25 PSI in the boiler. Drain a little water out until you get to 18-20 PSI. That will be your cold operating pressure.

Open all isolation valves, turn on your boiler and test for proper operation.

The reason for bleeding at high pressure is so the pressure doesn't fall below the feed valve factory set pressure and allow more water to enter the system, which brings air with it, after you are done.

I realize it's long but I hope it helps a little.
 
  #3  
Old 12-15-18, 06:34 PM
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Originally Posted by spott View Post
A,
First off you said you have 3 zones total yet your pics show 4 pumps.

The procedure you use to bleed the system is everything in stopping air from returning.

First thing is you never bleed the system with the boiler and pump on. Everything must be shut off so you are using natural water pressure, not increased by the pump.

Next, you have purge valves on each return line that should be used and not the vents on the baseboards.

Close all valves on zones not being bled so the zone being worked on is isolated and the water pressure being fed into the system will only go the zone being bled.

Next to your extrol tank you have an auto feed valve with a lever, when raised bypasses the valve and lets you manually fill the boiler.

You want to get your pressure up to 25-28 PSI and the open the spigot to remove the air from the zone. You must keep the pressure to at least 25 PSI when doing this and let the water continue to drain until you get a good stead stream of only water coming out. Don't be in a rush. After all the air is out let it run for a good couple of minutes or so to make sure you got it all.

When your satisfied, close the spigot and shut off the feed and proceed to the next zone and repeat the procedure.

When you are all done you should still have your 25 PSI in the boiler. Drain a little water out until you get to 18-20 PSI. That will be your cold operating pressure.

Open all isolation valves, turn on your boiler and test for proper operation.

The reason for bleeding at high pressure is so the pressure doesn't fall below the feed valve factory set pressure and allow more water to enter the system, which brings air with it, after you are done.

I realize it's long but I hope it helps a little.
Spott this is excellent information. I didn't know I couldn't bleed with it on and hot. I will try this tomorrow and report back.
 
  #4  
Old 12-16-18, 12:46 PM
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Well I turned the system off, went for some errands and came back a few hours later to try this bleeding procedure. I stood in front of the unit and held open the auto feed valve and watched the pressure gauge, it wasn't budging for maybe 10 seconds and the pressure relief valve on the boiler popped and spewed steaming hot water on the ground. SO GLAD I wasn't standing by it.

Because of this I don't think my pressure gauge is working. I can't maintain an elevated known pressure without it so need to run and get a new one. I let 10 gallons of water out of the the 2nd floor zone only with the auto fill valve wide open, then shut both valves, and could continue to hear the system filling for maybe 3 seconds after.

I will try and get a new gauge then report back. Unless I have this all wrong.
 
  #5  
Old 12-16-18, 02:56 PM
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A,
After seeing a close up of your feed valve's location you have a difficult situation when it comes to bleeding because of the way your system is fed into the supply line.

Your feed valve goes into a tee in your supply pipe which means when you open up the lever for straight street pressure the water is feeding 2 ways. Through the heating zone and also back into the boiler.

The problem is that the boiler is isolated from the system and the pressure has no where to go but out of the relief valve.

Once you shut the isolation valves off on the return line and run full pressure through each loop and open the spigot to bleed the air because the isolation valves are closed that water pressure doesn't effect the boiler or the relief valve.

It's the water that comes into the isolated boiler, which you cannot help, that will open the relief valve.

If they would have put a shut off on the supply line where that coupling is, you could close it and stop the water from going back to the boiler and forcing it just into the zones, and then once bled you could open it along with the return valves to properly run the system.

That is a lot of work to put a valve in that line. My suggestion would be to reroute your cold water feed into your return manifold at the bottom where your spigot is.

Remove the spigot and add another tee. relocate your feed line to that tee and reinstall the spigot on the end. That way your feeding in the return into the boiler and out into the loops only one way which will let you control the pressure.

It may be your gauge is fine, it just took a while to reach pressure because of the feed valve location.

The tee that is being used for the feed valve now can stay, just put in a plug or a nipple with a cap. No need to repipe anything there.

By relocating your feed to the return side you may find that your air vent might work a little better. Right now it's serving little purpose because the feed water comes in so fast it goes right by without a chance to bleed the air.

In order for that air scoop to work properly it must be 18" from an elbow on a horizontal pipe where the water isn't as turbulent and gives the air scoop a chance to work.

They make a better quality air remover called a Spirotherm that has no distance restriction and needs no air vent installed on it.

https://www.supplyhouse.com/Air-Eliminators-310000
 
  #6  
Old 12-16-18, 03:50 PM
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I get what you are saying about the way it is piped. I went to HD and got this pressure gauge

https://www.homedepot.com/p/Watts-3-...IWTG/100175467

and connected it to the manifold beneath the discharge end of the recirculators. I was able to manually open the city water in and see the pressure rise just below 30, then closed all but 1 isolation valves for all but one zone. I had my wife read the gauge above 25psi while I played with the zone purge valve and manual city water in valve. I did this for all three zones, but to your point - the water was probably just short circuiting through the boiler and not purging the lines like I hoped.
 
  #7  
Old 12-16-18, 04:36 PM
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A,
If you went through the feed valve and had ALL the isolation valves closed you went through the loops plus fed the boiler but at long as you kept it under the 30 you are good. When it fed into that tee it fed in 2 directions and one was through the loop, which is what you wanted.

If you left an isolation valve open the water probably short circuited through the boiler and back fed out of the spigot. You must close the isolation valves on the return lines to force the water through the loop and stop it from back feeding into the boiler and out of the spigot.

As long as you kept it at 25 or above and when finished, drained a little out to get down to about 20 PSI operating pressure you should be fine. Just make sure all valves are open and then test boiler for proper operation. It should be quite and give you heat.

That gauge is fine for testing.
 
  #8  
Old 12-16-18, 05:45 PM
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Well I went ahead and turned on all of the zones. No ketteling, sloshing or popping. I am cautiously optimistic. Even if it's not fixed you have given me a lot more insight on how my system works and input in if I decide to have someone come in and replace or modify my system. As much as a random person on the other side of the screen can give, I thank you greatly for your help spott!
 
  #9  
Old 12-29-18, 10:32 AM
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Update: My system still has tons of air in it. Purging the system as Spott described only helped for a few days. I investigated the taco air scoop above my expansion tank and also the Hy-Vent attached to the top of the air scoop. The valve on the top of the Hy-Vent was fully closed.

https://www.homedepot.com/p/1-8-in-H...00-4/202312925

Unbeknownst to be this valve should be open to let air out (duh). When I open it water floods out, which is why it was shut to begin with. This means that the vent is most likely broken or needs maintenance. I am going to go to the local big box to get a new valve and will update.

A
 
  #10  
Old 12-29-18, 12:17 PM
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A,
Sorry to hear about your continuing air problem but if it lasted for a few days it should have been good until the system was worked on again.

You have another problem somewhere, either a slow leaking autofeed valve or a leak somewhere in the system.

Once you completely remove the air from a closed system such as your heating system the only way for air to be introduced is with fresh water being added to the system or if you have a defective fitting such as a bad pump gasket or defective vent or loose fitting somewhere. It doesn't have to be bad enough so that water leaks out but enough that when the pump comes on it creates negative pressure to suck the air in.

If nothing jumps out at you I would start by bleeding the system again and then close the ball valve before the auto feed to see if the feed valve is leaking by. Keep an eye on your pressure gauge to see if it starts to drop. This will indicate a leak somewhere that is being replaced by the fill valve until now because you have it shut off. If you feel you pipe on your feed valve if it is constantly feeding, the pipe will be cold or cool to the touch. It should be warm or room temp. Cool means it's been feeding water for some reason and must be stopped.

I noticed that you have a plug in your vacuum breaker before the feed valve. That should be open and if it was leaking, that is a sign there is a problem somewhere. That V.B. works on pressure changes and should not leak until it senses something or the valve is getting bad.

Check your pump flanges and unions to make sure they are tight and if you have any hi-vents on lines in your system other than the one you're changing, close the caps tight so no air can be sucked in.
 
  #11  
Old 12-29-18, 03:10 PM
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Spott ,thanks again for your continued support. I know it's hard to help someone online not seeing the full system but I want to remind you that my system isn't fully closed, because the boiler fills a domestic hot water tank that we use for showers, laundry dishes etc. This means every time we use hot water in the house my system refills with city water - which is seemingly dumb - not sure of any advantages to this setup.

I changed the Hy-vent air separator valve. The old one had tons of corrosion and it looked like the float could easily get stuck inside. I replaced it with a new one I got at HD for 15 bucks (I taught 2 employees what the thing was when looking for it!). The installation was super simple. I closed pretty much all my isolation valves, drained the system a little and unscrewed the old (needed some PB blaster) and screwed the new one with a few wraps of teflon. I recharged my system with water (at higher pressure like Spott instructed me before), bled back down to normal and started it up.

Upon start up with the new Hy-Valve, I heard it spit air out and then clunk close - like it should work! Now I know I have a functioning air separator for my system I have high hopes the air will not accumulate in the future.

If this is the solution, the moral of the story is make sure your air purge vent is working - not fouled, or manually closed.
 
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Old 12-29-18, 03:49 PM
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I must be mixed up or something. You mix boiler water with your drinking water? That could be unhealthy.

You may want to pay somebody you trust to look over your system.
 
  #13  
Old 12-29-18, 03:49 PM
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A,
You do have a closed system. Your hot water tank which is called an Indirect Hot Water Heater is nothing more than another zone off your boiler. Inside that tank is a coil that runs right up through the center which hot boiler water flows through and is completely separate from your domestic water which surrounds it.

That hot water coil heats the fresh surrounding tap water. You have 4 pipes on your tank. Two are from the supply and return from the boiler, just like a supply and return to your baseboard. The other 2 lines are for fresh cold water and heated hot water to your taps.

Whenever you draw hot water, fresh cold water enters to be heated but has NOTHING to do with your boiler. That water is in the coil and circulates from the coil back to the boiler to keep getting reheated like your baseboards and the 2 systems in the tank are completely different.

Hope this helps a little.
 
  #14  
Old 12-29-18, 03:53 PM
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This is just to take up space. It says duplicate and will not let me do anything so trying this.
 
  #15  
Old 12-29-18, 04:00 PM
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gil,
If you look at the pics he has an Indirect Hot Water Heater. I think he is just confused on how it works.
 
  #16  
Old 12-29-18, 04:47 PM
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Have you replaced the pressure gauge yet and verified that where it screws into the system it is not clogged with rust or sediment?

I am guessing that you have more air re-entering your system due to too low boiler pressure.

Try this:

If needed, add water to the system so that boiler pressure (c is around 12-15 PSI cool or around 25 PSI hot.

Turn off the boiler (and all zones) and wait 2 hours.

Use the bleeder valves (vents) on the radiators and not the spigot to let air out.

Keep an eye on the pressure gauge to be sure it does not drop close to zero. Add more water to the boiler to keep the pressure in the 12-15 range cool, can be around 25 PSI when hot.

After all the radiators have been bled, add water a final time to get to 12-15 cool or 25 hot.

Next day repeat this whole process. After 3 or four sessions and days call it quits and see if the problem is gone;.
 

Last edited by AllanJ; 12-29-18 at 05:12 PM.
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