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forced hot water air

ChrisJ
ChrisJ Member Posts: 16,230
in THE MAIN WALL
I'm still helping my brother-in-law out with his forced hot water heat and he brought up another concern.  Pretty much every fall he has to bleed air out of a radiator or two (or in his case, convectors).  Is this normal, or does it indicate the system is taking in makeup water?



My assumption was these systems are tight and once bled, should not need to be bled again unless work is done.



Thank you for your time.



Chris J
Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment

Comments

  • Paul48
    Paul48 Member Posts: 4,469
    Questions

    What pressure does he maintain the system at? Is there a means of automatic air removal on the system?
  • LarryC
    LarryC Member Posts: 331
    Low static system pressure?

    ASSUMING the system has no water leaks and there is not an automatic makeup connection that is masking any leaks, the air could be coming from the pump sucking the air in because it is at a lower pressure than atmospheric.



    Is the system set up so the circulating pump suction is directly connected to the Point on No Pressure Change (PoNPC) also known as the expansion tank.  If not, when the differential pressure across the pump plus the pressure drop to the PONPC is greater than the system pressure, the pressure at the suction port of the pump may be below atmospheric pressure.  Most circulators will draw air in thru the pump seals under these conditions.



    A tempoary fix is boosting system static pressure so that this condition doesn't exist anymore.  However your upper limit is the 30 psi safety release valve pressure setting.

    A better fix involves moving the pump(s) suction over to the PONPC so that the pump suction never goes below atmospheric.
  • ChrisJ
    ChrisJ Member Posts: 16,230
    Replies

    Thank you for the replies.

    I will look into what has been mentioned, I *think* he has it at 12PSI and its a single floor ranch.



    I'm also looking into buying some of Dan's books on this as I love the ones I bought on steam. Now I get to learn a whole new beast :)
    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
  • Steamhead
    Steamhead Member Posts: 17,312
    Get "Pumping Away" first

    it goes into detail about what LarryC mentioned. I bet you find that's the problem.
    All Steamed Up, Inc.
    Towson, MD, USA
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
    Consulting
  • ChrisJ
    ChrisJ Member Posts: 16,230
    edited September 2012
    Pictures

    I ordered a copy of Pumping Away so I should have it within the next week or so.  In the mean time I had my sister snap a few pictures and email them to me. 



    What I found strange is it appears the water feed is shut off.  I always assumed the pressure regulator on these controlled the feed water automatically so why would the feed be shut off?  As far as the term "pumping away" I understand this is in regards to the expansion tank.  In the case of my sisters boiler I am not sure what category this falls into?  The expansion tank is on the suction side of the pump in relation to the boiler.



    I'm also concerned about the lack of pitch on the water heater vent, but thats another story.
    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
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