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Where is the air coming from??

Glenn_5 Member Posts: 13
I had a hot water boiler replaced 1 year ago. After the replacement, we had constant problems with noise in the system. After reading information from this site and the addendum to the installation manual for my Carrier BW2 (140,000 BTU) boiler, I found the circulator was installed on return side. The contractor returned and agreed to move the circulator to the supply side, although they indicated it was not neccessary. They also installed a "purge" valve, it looks like a drain valve, on the return side for $150 (I now think I paid for the moving of the circulator). This purge valve was to be used to bleed the air from the system. I still am bleeding air from all 4 zones.

After taking a good look at the system I found that the Airtrol tank fitting (ATF-12) is not connected to the supply piping, but to a tee on the relief valve. The installer indicated this connection is fine because there was not enough room to install it after the circulator without moving all the zone valves. Could this be a source of my problem?

I bleed each zone separately without running the pump. The system will be quite for a week or so and then it starts all over again. The system gurgles, gulps and gushes. Any ideas on what is going on??


  • Weezbo
    Weezbo Member Posts: 6,232
    that is interesting ...no. purge valves dont have

    a place to install an expansion tank...you must be mistaken. relife valves are open to air, so the "T"its connected to Must be on the Boiler .....other formations exist however because you are having to bleed air off you are having make up water problems probably bought about from pressure differential changes...
  • Uni R
    Uni R Member Posts: 663

    Why would he want to install the airtrol AFTER the circulator? I'm no expert but the Airtrol is used to keep air in the tank "IN" the tank and not let it sneak out in solution. I wonder if it is working properly? Essentially it is like a straw that sticks up into the tank so that the air can't escape through the water. Also, if your water tank had too much water in it and your tube isn't max height, then that would also stop your Airtrol fitting from doing its job since it would be submerged. I'll be as curious as you to find out what is going on. Maybe it's time to get a bladder tank? ;-)
  • David Efflandt
    David Efflandt Member Posts: 152
    Do you have a leak?

    Depending upon source of makeup water, heat will drive air from the water. So if you have regular makeup water (due to a leak), air driven from that can accumulate. This can especially be true for surface water (lake/river) or water aerated during treatment.

    As a side note, since backflow preventer and expansion tank were added at work, our hot tap water is white (cold water is not). The whiteness (air) dissipates in a few seconds at atmospheric pressure. The point is, if you have makeup water due to a leak, lower pressure and higher temperature can release air from it. Stop the leak, and it will stop the influx of air laden make up water.
  • Empire_2
    Empire_2 Member Posts: 2,343
    House Size

    Can we get height, length of the house and aslo existing pipe size of origional piping...? Not what the boiler was piped with, but origional pipe. Does any pipe go through a crawl space? "In reff. to leak".?
  • Glenn_5
    Glenn_5 Member Posts: 13

    The purge valve was installed on the return line. There is a "T" off of the boiler, one line goes to the Airtrol and the relief valve is on top of "T". The Airtrol is also tied into the cold water inlet. There is also a 1/4 turn valve between the "T" and the Airtrol.
  • Glenn_5
    Glenn_5 Member Posts: 13

    I shut off the water supply line (domestic municpal system) to the boiler and left it that way for a day. There was no drop in the pressure. Is this a good way to make sure there is not a leak?
  • Glenn_5
    Glenn_5 Member Posts: 13

    House in approx. 45' x 35' and a 2 story ranch. The piping to and from the baseboards is 3/4". These 3/4" returns tie into what looks like 1-1/2" piping and then into the boiler.
  • Glenn_5
    Glenn_5 Member Posts: 13

    City water
  • jim_49
    jim_49 Member Posts: 24

    If you have a extrol tank on the boiler, that could be your problem. Put a ceiling hung EXPANSION TANK on the boiler tapped off your air scoop or off top of boiler. Make sure your press. is high enough for the height of the piping in structure and close all auto air bleeders. As the system runs air will be eliminated automatically into the tank.
  • Glenn_5
    Glenn_5 Member Posts: 13

    I have a ceiling mounted expansion tank.
  • Glenn_5
    Glenn_5 Member Posts: 13

    Anyway to tell the water level in the tank? I don't have a sight glass.
  • Dale
    Dale Member Posts: 1,317

    So, you seem to have the old style steel tank, these tanks like all expansion tanks should be connectec from an air separator before the pump which is now on the supply. The piping to this tank should go( slope or straight up upward) through a full port ball valve from an air separator like the old B&G IAS to a B&G airtrol tank fitting. I would shut off the tank, drain it and start from there. With a ceiling tank there must be an easy way for the air to get back to the tank. Go to the B&G site for a real picture.
  • jim lockard
    jim lockard Member Posts: 1,059
    Auto Bleeders

    Glen- do you have auto bleeders (can vents) scattered around the system if so they could be sucking air. best wishes J.Lockard
This discussion has been closed.