Do air scoops go bad?

MikeAmann

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.

Big Ed_4

Maybe you used too much teflon tape ?

MikeAmann

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.

MikeAmann

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

Yours did🤓

MikeAmann

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

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

MikeAmann

@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

@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

mattmia2

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

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

EBEBRATT-Ed said:

@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

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 .

Adk1guy

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

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

MikeAmann

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

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

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

And the 18” of straight pipe before the purge “coupling” ??

EdTheHeaterMan

Do air scoops go bad?

Never...

Except yours! Mike

Nice training photos though.

Big Ed_4

" You would shot your eye out "

SuperTech

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

Although that huge boiler probable makes a pretty good air separator.

MikeAmann

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.

EBEBRATT-Ed

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

SuperTech

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.

unclejohn

IMO The air scope is bad when you take it out of the box 

Lance

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

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.

MikeAmann

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.