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Do air scoops go bad?

MikeAmann
MikeAmann Member Posts: 645
edited November 20 in Pipe Deterioration
The type with the air vent on top and your diaphragm expansion tank connected to the bottom.

I had previously moved my expansion tank to the boiler return pipe so that it would be on the suction side of the circulator, but when I tried to move it back to the air scoop last night, the casting cracked.
My nearly new air vent stopped working, even after a cleaning, and it appears that the expansion tank is not doing its job either. The common part connected between them is the air scoop.
Thoughts?
I put this in PIPE DETERIORATION because 50+ years of use has obviously weakened the casting.

Comments

  • Big Ed_4
    Big Ed_4 Member Posts: 1,970
    Maybe you used too much teflon tape ?
    I have enough experience to know , that I dont know it all
    mattmia2SuperTechEdTheHeaterMan
  • MikeAmann
    MikeAmann Member Posts: 645
    edited November 19
    Why was I moving the exp tank back to the air scoop?
    Answer: boiler supply --> next in line after the air scoop/air vent/exp tank combo is a TACO Flo-Chek (a check valve).
    The CIRC is on the boiler return side pumping into the boiler. I don't know for sure, but let's suppose that the circ has the removable check valve. See where I am going with this?
    The boiler now has check valves on both the inlet and outlet, and the expansion tank is no longer connected to the boiler itself. The expanded water now has no place to expand to, and I figured that this is the reason why the system pressure goes from 5 psi COLD to 24 psi HOT.
    mattmia2
  • MikeAmann
    MikeAmann Member Posts: 645
    Big Ed_4 said:

    Maybe you used too much teflon tape ?

    Nope, 3 wraps. And no resistance screwing it in. Casting weakened from 50+ years of use.

  • hot_rod
    hot_rod Member Posts: 17,531
    Yours did🤓
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    MikeAmann
  • MikeAmann
    MikeAmann Member Posts: 645
    edited November 20
    Ha-ha. It's going to be a major PITA because its black iron pipe at the ceiling above the boiler.
    I plan to sawzall on either side of the air scoop and then the fun begins trying to remove the rest of the two nipples. One I can do on the bench because I will be adding a copper union after the Flo-chek, but the black pipe coming up out of the boiler that runs up to the ceiling frightens me.




  • hot_rod
    hot_rod Member Posts: 17,531
    edited November 20
    Maybe look at a vertical air separator to simplify replacement, a micro bubble type
    This brand here is a 19cv in 1”. Other brands don’t list their flows, very restrictive I suspect😆

    Do you need that flo check. They add a lot of pressure drop, could be a good time to add a hydronic spring check
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    STEVEusaPAmattmia2EdTheHeaterMan
  • MikeAmann
    MikeAmann Member Posts: 645
    edited November 20
    @hot_rod
    That would be a nice upgrade, but the house should be sold in the near future.
    I just want to get the system to be trouble free and reliable.
    It's old and a new owner will probably rip it all out.

    1" Flo-chek = 54 CV for soldered. Double for threaded! Holy crap.
    But now you have me thinking...... do I really need the Flo-chek AT ALL?
    The whole house is 1 loop. No zones. Tankless coil not in use. LO Limit disabled. Separate HW heater.
    The boiler is only for heating the house. Who cares if there might be a little gravity flow.
    The boiler is ON because we need heat.

    It would simplify the piping if I really don't need it.
    Then I could keep the exp tank in the return piping (my preferred location) and it would be on the suction side of the circ. Still not truly PUMPING AWAY, but at least not pumping towards it.
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 12,654
    @MikeAmann

    Saw right through the air separator. Then back the LH piece out and leave the nipple intact. You can start from there and work towards the copper.

    Never seen an air scoop go bad

    mattmia2MikeAmannEdTheHeaterMan
  • mattmia2
    mattmia2 Member Posts: 6,655
    The dual flow checks do not prevent the expansion tank from working. the additional pressure will flow forward through the flow check until it reaches the tank around the loop.

    cut the already cracked scoop almost to the threads, hold a small sledge behind it to hold it in place, and split the cut with a cold chisel and unscrew it.
    MikeAmann
  • mattmia2
    mattmia2 Member Posts: 6,655
    The flow check was there to keep it from gravity circulating when the tankless was calling, don't need it if you are never going to run a tankless or indirect again.
    MikeAmann
  • MikeAmann
    MikeAmann Member Posts: 645

    @MikeAmann
    Saw right through the air separator. Then back the LH piece out and leave the nipple intact. You can start from there and work towards the copper.

    mattmia2 said:

    The dual flow checks do not prevent the expansion tank from working. the additional pressure will flow forward through the flow check until it reaches the tank around the loop.

    cut the already cracked scoop almost to the threads, hold a small sledge behind it to hold it in place, and split the cut with a cold chisel and unscrew it.

    mattmia2 said:

    The flow check was there to keep it from gravity circulating when the tankless was calling, don't need it if you are never going to run a tankless or indirect again.

    GREAT ideas guys. You are the best. You just made my job a whole lot easier. BIG Thanks!
  • Big Ed_4
    Big Ed_4 Member Posts: 1,970
    edited November 20
    Those fittings are cast , Your looking to redo ? Cut the copper and crack that elbow. Bring it down in 15 . Strap the weight ...Then Run all new .
    I have enough experience to know , that I dont know it all
    MikeAmann
  • Adk1guy
    Adk1guy Member Posts: 39
    The cast fittings are easy to break. I hold a 10 lb sledge on one side and strike the opposite side with a 5 pound or even a ball peen hammer.
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 12,654
    edited November 20
    Breaking cast fittings is fine ......If you got the room to swing the hammer and have a bigger hammer behind it for a back up.

    A lot of time there is no room to swing a hammer due to floor joists, other pipes electrical conduit etc.

    Best way is an angle grinder and a thin cutting disk or a sawzall. Cut both sides of the fitting.......the crack has to be able to open up. Cutting the back side of the fitting allows this. Cut down close to but not into the threads

    Then drive an old screwdriver in the crack and the fitting splits with a lot less pounding and less risk of
    causing another leak or damaging another fitting.

    Mt 2 cents
    WMno57Larry Weingarten
  • MikeAmann
    MikeAmann Member Posts: 645
    DUH! I can't believe that breaking the casting off the nipple didn't even enter my mind. So simple and QUICK.
    I gathered what I need last night - sawzall, air cut-off wheel, and air chisel. I have the BFH and chisel if needed also.
    Tuesday afternoon's plan -
    • Lower the water level.
    • Fasten a strap to what is going to be removed.
    • Saw through the air vent as near as I can on the left side to keep the nipple threads undamaged.
    • Cut the copper pipe at the other end that leads to the baseboards. Remove that whole mess.
    • Use the cutoff wheel to make a few slices in what remains around the nipple.
    • Chisel a piece or 2 off so that I can easily unscrew what remains. That was the hard part.
    • Install a hangar on that nipple. The floor joist is right above.
    • Install new air scoop and air vent. The bottom will be plugged because the exp tank is going back to the return piping (better location).
    • I no longer need the Flo-Chek, so it will be 1" copper back to the baseboard piping with a union for future convenience.



  • MikeAmann
    MikeAmann Member Posts: 645
    edited November 23
    Completed. And I owe you guys a beer! The cast iron snapped just like you said and the rest unscrewed. The nipple was perfect. The hardest part of the job was that hangar. And draining and bleeding - takes quite a bit of time. I had to wait until the union got hot to be able to get it to stop dripping.
    And the shoelace..... it's my little idea for if the air bleeder does squirt a little water, then it can follow the shoelace and drip down to a place that I want it to go.

    Happy Thanksgiving everyone!






  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 12,654
    A cut off wheel on a grinder is one of the best tools invented. People fool with snapper's on CI sewer pipe and I don't know why, I am not a plumber just a stupid pipe fitter. But I had to cut an 8" CI sewer pipe once and the cut off wheel cut it like butter. Much better than a sawzall.

    And once you get the hang of a grinder and cut off wheel it is very accurate. I only use the sawzall or better yet a Milwaukee "Hackzall" on the inside of fittings
  • hot_rod
    hot_rod Member Posts: 17,531
    And the 18” of straight pipe before the purge “coupling” ??
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    SuperTech
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 4,271
    edited November 23

    Do air scoops go bad?

    Never...

    Except yours! Mike

    Nice training photos though.
    Edward Young
    Retired HVAC Contractor from So. Jersey.
    Services first oil burner at age 16
    P/T trainer for EH-CC.org

    MikeAmann
  • Big Ed_4
    Big Ed_4 Member Posts: 1,970
    " You would shot your eye out "
    I have enough experience to know , that I dont know it all
  • SuperTech
    SuperTech Member Posts: 1,836
    hot_rod said:
    And the 18” of straight pipe before the purge “coupling” ??
    I was thinking about this too. If you don't have enough room for the required 18" of straight pipe before the scoop that is needed for it to work correctly then you really should have installed a much superior microbubble resorber air eliminator.  
    mattmia2
  • mattmia2
    mattmia2 Member Posts: 6,655
    Although that huge boiler probable makes a pretty good air separator.
    MikeAmann
  • MikeAmann
    MikeAmann Member Posts: 645
    As always, you guys are correct. This is how the system was for 55 years. And it worked, despite my father incorrectly tying in a wood-burning stove. But that heated the house for decades.
    I just needed to get this back together and functional. I bled all the air that I could, but still had a ton circulating through the pipes. It seemed as though the air vent wasn't doing anything, I was listening for the pressure cooker sound that didn't happen, but an hour later the air was gone and the pipes were quiet.
    Sometimes things just work despite what the theory says should happen.
    SuperTech
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 12,654
    Not every job needs to be textbook to work. One day in the field looking a crappy install that somehow run will tell you that.

    Good job Mike
    MikeAmann
  • SuperTech
    SuperTech Member Posts: 1,836
    I agree that it doesn't have to be textbook.  I've seen more jobs that work even though they aren't 100% correct than ones that are done by the book. I see boilers without any air scoops every week.  They usually only have one 1/8" auto vent on the boiler. Sometimes these boilers have air issues, sometimes they don't. I think you did a great job as well Mike.


    MikeAmann
  • unclejohn
    unclejohn Member Posts: 1,778
    IMO The air scope is bad when you take it out of the box 
  • Lance
    Lance Member Posts: 227
    Thats ok, it can be used as an anchor, a garden ornament, add a pipe stand with two legs, two elbows to two floor plates for a coat holder and a pipe on top with a cap for a hat! :)
  • hot_rod
    hot_rod Member Posts: 17,531
    you’ll be fine with that scoop

    High efficiency boilers really need micro bubble purgers. It’s the small micro bubbles that you don’t hear, or see when you manually purge that can reduce the boiler efficiencies. With thin  metal heat exchangers you want all air gone to prevent hot spots on the tube wall.  
    Cast boilers are less sensitive and better at collecting air up top in the sections and continue to run.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    MikeAmann
  • MikeAmann
    MikeAmann Member Posts: 645
    Everything is working great now.
    Between the cleanings and overhauls that I have done to the boiler and HW heater, and correcting both burners' adjustments for proper combustion (each yielded 85% efficiency), installing the SS baffles from my boiler, adding a baro damper and all of the other corrections, I can see Mom's house getting through the winter on only ONE 275 gallon tank of oil. :)