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Cleaning/Replacing Air Separator and bleeding air from lines

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Screen196
Screen196 Member Posts: 7
edited March 2017 in THE MAIN WALL
First and foremost, please excuse my novice questions but I figured who better to ask than the experts so here goes...I am looking to clean, replace if needed, the supervent top on my air separator and subsequently bleed the air that is in the lines. Being a new homeowner I am a novice when it comes to boilers but I do like to consider myself handy so I figured I would take on this project on myself. It all started after hearing a wave like noise in my pipes I decided to call the local heating company. The tech that came out determined that there was air in the lines. He then bled the air out, which was a significant amount, and told me that if it returns, it may be due to a clogged air separator. Unfortunately since then air has significantly returned which brings me to my questions. First I was wondering if it was possible to valve off the air separator with the setup I have so that I may inspect it and avoid draining my whole system. If so, what's the best way to do it and purge any residual water that may be in the valved off pieces of pipe. Secondly, I was unsure on how to bleed the lines being that there is no spicket on the return lines prior to the water reaching the boiler itself. The only spicket I can see using would be the one on the supply line before the air separator and circulator pump. What worries me is that I am under the impression that pumping cold water through the boiler may damage it being that all videos I've watched, the boiler has been shutoff and the air is bled through a spicket before it reaches the boiler. I have included pictures of my setup to provide a visual reference. I am open to any "how to" instructions, advice, tips regarding this and anything else you guys/gals may notice in the pictures. I am also willing to provide any other pictures if needed. Thank you all in advance for help.


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  • Bob Bona_4
    Bob Bona_4 Member Posts: 2,083
    edited March 2017
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    That's quite a, um, setup you got going there :) Shut off boiler. You can isolate the sep with the ball valves on the return and the zone valves or ball valves above. Do the same with the indirect tank piping. Shut off boiler feed, and let pressure off via the purge valve above the low water cutoff tapping. Then do the seperator work. Fill back up until pressure is back to 12-15 lbs, and then open isolation valves. You may or may not need further purging.

    The piping is slightly unorthodox but no harm should occur to boiler the way the purge station is.
    Screen196
  • Screen196
    Screen196 Member Posts: 7
    edited March 2017
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    @Bob Bona Thank you Bob for your prompt response and advice! I understood most of what you explained but it left me with a few questions and I apologize if the answers may seem obvious. So here goes, is the purge valve above the low water cutoff piping the one pictured with red knob? Also would that also be the spicket I use to bleed the system of the air being that I don't have any on the return lines and that seems to be the only spicket prior to the water flowing back through the house? Also, when I bleed the system should the boiler remain on since water has to pass through it prior to me bleeding it? Once again I thank you in advance!!!!
    Bob Bona_4
  • HVACNUT
    HVACNUT Member Posts: 5,857
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    Yes, the red handle drain valve. Close the ball valve above that.
    You will need to manually open your zone valves, one at a time to purge that particular zone. There are levers on the valves. Push open and lock into place. You can also purge your water heater from the setup near the bottom of the tank.
    Your purge is set up like that so that you purge air through the boiler, rather than just the zones.
    Bob Bona_4Screen196
  • psb75
    psb75 Member Posts: 843
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    Maybe, loosen the little brass cap on the top of your air vent.(bottom right in your third posted pic.)
    Bob Bona_4Screen196
  • Screen196
    Screen196 Member Posts: 7
    edited March 2017
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    @HVACNUT : Thank you sir!!! One last question if you don't mind...should I shutoff the power to the boiler while purging the air from the lines? I'm not sure where I read it but I had read before that running cold water through a hot boiler would actually cause damage. Excuse the questions, I'm an extreme novice and want to make sure I take all the precautions necessary so I don't damamge the boiler.

    @psb75 : I tried that already. I really hoped it was the problem but unfortunately it wasn't. The brass cap is extremely loose and air is still being introduced to the lines.
  • JUGHNE
    JUGHNE Member Posts: 11,074
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    Do you have a pressure gauge anywhere on the boiler?
    If so what does it show with everything off and the boiler only lukewarm at the most?
    Screen196
  • Screen196
    Screen196 Member Posts: 7
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    @JUGHNE : I do have a pressure gauge on there. It's right above the two silver relays. I believe it shows the temperature of the water in the system and the pressure in the lines. As for the reading while the boiler is lukewarm, I'm not sure. I would have to test it. As a novice, I'm curious to know why that would be important. As always thank you for your comment.
  • JUGHNE
    JUGHNE Member Posts: 11,074
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    Post a picture of the gauge. You should have some pressure shown always. The lukewarm comment was to see the pressure with the boiler water not blazing hot. When hot the pressure may increase somewhat.
    Show us the gauge we can see the pressure and water temp.
    Also tap it as the needle could be stuck.
    Screen196
  • Screen196
    Screen196 Member Posts: 7
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    @JUGHNE: Currently stuck at work but I did check the gauge last night while the boiler was blazing hot and the water temp was at 170 degrees and the water pressure was around 22PSI. I will post one tonight while the boiler is lukewarm.
  • Screen196
    Screen196 Member Posts: 7
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    I really appreciate all the advice. My last question is whether or not I should shutoff the power to the boiler prior to purging the lines. I only ask being that due to the location of the purge valve the water will have to pass through the boiler prior to it being purged and I want to make sure that having the boiler off will not cause it any damage. Thanks in advance!!!
  • Bob Bona_4
    Bob Bona_4 Member Posts: 2,083
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    Shut off boiler. If a pump is running during purge, it can cause agitation/cavitation. You don't want that.
  • BornForDying
    BornForDying Member Posts: 40
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    I would shut it off and let it cool down a bit. That way you arent handling very hot water.

    As long as you dont drain all of the water out of the supply pipe when you work on the separator, you may not introduce that much air
  • Screen196
    Screen196 Member Posts: 7
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    Thank you ALL for your help. I will keep you posted as to how it goes. Hoping to get this done this weekend.