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Not Pumping Away!

DanHolohan Member, Moderator, Administrator Posts: 16,393
needed on the flow-control valves, and they should be in a horizontal pipe if they are the weighted-check type of valve. If you're using an internal flow check (such as Taco's) the circulator can be in the vertical position.

There's much more about primary-secondary piping in Primary-Secondary Pumping Made Easy! than there is in Hydronic Radiant Heating.
Retired and loving it.


  • elamcup
    elamcup Member Posts: 8
    Not Pumping Away!

    I read Dans book, Pumping Away yesterday. I have been struggling with air in my two pipe direct return heating system since the Ultra 155 was installed 18 months ago. Now I know why. The diaphragm expansion tank mounted to the bottom of the air scoop is the only thing that isn't wrong.

    This summer the system will get repiped, until then I just have to deal with it. Someone on the wall suggested raising the system pressure. That cut down most of the noise, but I still have air in the system. Today I raised the air pressure in the diaphram tank to match the system pressure so I don't ruin the blatter. Henery's Law addressed raising the pressure at a constant temperature will put more gasses into solution. What effect does changing the temperature have? I need to search that out.

    I have some questions that wern't covered in the book. I will reuse the two secondary loop circulators. I need to replace the flo-checks, they are leaking. How far from the circulator does the flo-check need to be? Should it be in a horizontal pipe run with the circulator and air seperator so natural circulation doesn't try to push it open when the circ is off?

    Does Dan's book, Hydronic Radiant Heating cover issues on installation like this? I want to make sure that everything gets installed correctly the second time around.

  • Tom Elam
    Tom Elam Member Posts: 57

    Thanks for the help Dan, Tom
  • Tom R.
    Tom R. Member Posts: 139
    Changing temperature

    at any pressure tends to release air in the water. The hotter the water, the less air can remain dissolved. Besides the air scoop, you still need vents placed at high points. (and seal your leaks. Make-up water contains loads of dissolved oxygen).
  • Tom Elam
    Tom Elam Member Posts: 57

    Thanks Tom, I did a web search and found Henry's Law. I lowered the boiler water temp setpoint to 150 degrees this morning and the house is still being heated properly. I still hear air but it isn't as loud. I may drop the temp to 140.
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