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Hydronic air removal

RayWohlfarth
RayWohlfarth Member Posts: 1,073
We installed a replacement hydronic boiler this summer and still having problems with air pockets in the system We installed a new Spirovent and I have tried every trick I know to get rid of the air. The system has two manual valves on the returns.
Cycling boiler and pump on and off
Bleeding the vents.
Closing one zone valve for ten minutes and then opening it. We repeated the process for the other zone
I believe we got it working and now the owner wants to install glycol and i dread trying to find the air pockets during the winter
Just curious to see what your tricks are to remove air pockets
Thanks
Ray


Ray Wohlfarth
Boiler Lessons

Comments

  • HomerJSmith
    HomerJSmith Member Posts: 1,927
    I use a lawn pump with 75'hd. I pump it into each zone and the return from the zones moves into a large container which goes to the pump. I circulate the water till no bubbles show up in the container. There is enough flow to remove any air regardless of the height or configuration.
    I bought your book.
  • RayWohlfarth
    RayWohlfarth Member Posts: 1,073
    @HomerJSmith Great idea Never thought of that. Thanks for buying my book.
    Ray Wohlfarth
    Boiler Lessons
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 13,169
    edited January 12
    Probably oversized pipe for the flow. Is it monoflow?

    Glycol will be a little tougher as it tends to foam. @HomerJSmith advise sounds good to me
  • HomerJSmith
    HomerJSmith Member Posts: 1,927
    edited January 12
    Has garden hose connections.
  • Dave H_2
    Dave H_2 Member Posts: 520
    Raise the water pressure in the system till just before the relief valve pressure. It will "squish" the bubbles smaller and get them moving to the air eliminator
    Dave H
  • RayWohlfarth
    RayWohlfarth Member Posts: 1,073
    @EBEBRATT-Ed This job was the low bidder who knew nothing about hydronics.
    @daveh-2 I like that idea
    Ray Wohlfarth
    Boiler Lessons
  • hot_rod
    hot_rod Member Posts: 18,279
    edited January 13
    Raise the pressure, raise the temperature. If that doesn't work a pump with 10- 15 gpm flow, like shown.

    Are you sure Mr Spiro is working? Do you ever hear air come out?

    It's rare for air to pass through an operating microbubble resorber, maybe some milky looking entrained air, but not noisy bubbles.

    Glycol doesn't give up air easily! Maybe pump in a 100% solution instead of another drain down.
    There are some air entrainment chemicals that sometimes get added to those clear demos you see at trade show, if they have glycol in them. :*
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • Mad Dog_2
    Mad Dog_2 Member Posts: 3,942
    All great advice.  One of my mentors and often boiler install partner, Jimmy The Gent Burke (The Long Island Heating King NOT the Irish Mobster from Howard Beach who I lived around the block from!) Taught me 
    "The Urban Purge" as he called it with the pump and glycol in a big drum while we purged a large snowmelt field We did.  Wr got every last bubble out out.. Jimmy wasvthe master at purging and fixed many a job that everyone else said was piped wrong blah blah blah.. He'd come in and do his magic and heat would flow!!   The thing with snowmelt is that THERE IS NO HIDING from the air pockets or if your tubing layout was too far apart because you could see the stripes of snow that didn't melt.  On that job, which we practically did at cost (for the experience 🤔..TUITION DAN!!!) to keep cost down we went with A Honeywell-Braukman Air Eliminator.  Ripped it and put in a Genuine Spirovent a few seasons later when a pump crapped out and we were dying trying to get the air out.  Mad Dog
  • RayWohlfarth
    RayWohlfarth Member Posts: 1,073
    thank you gentlemen
    @hot_rod I will try your suggestions. The Spiro does work. I have heard it several times. Doing some more digging, I found a couple places where the loops went up and then down and there is no vent. When we drain the system to install the glycol, we are installing vents in several of the places.

    I love that this industry teaches me something every day.
    Ray Wohlfarth
    Boiler Lessons
  • JUGHNE
    JUGHNE Member Posts: 10,331
    Ray, I had this problem with a system in a 1961 10,000 sq ft school.

    The firetube boiler needed it's every 4 year internal inspection.
    This is the third time I have done this and the isolation valves always held.
    This last time there was an air block in 2 hallway convectors.

    One of them would often have the problem and bleeding air out thru the unit unions would take care of it. This time 2 units were persistent in not passing water.

    And the unions (and myself) are getting tired of cracking open and closing.
    I was able to drill and tap 1/8" air vents on those as they had isolation valves for the convectors.
    Air was bled numerous times, unit would heat for a few hours and then stop.

    This is a single story with boiler on ground floor and all supply and return piping is hidden up in the ceiling. Maybe 12' max height.

    This had always worked with 12-15 PSI since the beginning.
    I cranked the pressure up to 20 PSI hot and returned a few days later and the problem child was heating.

    The original 80 gallon ASME compression tank is still in use.
    It has the Airtrol boiler fitting and the Airtrol tank fitting.

    It has not been water logged since realizing (some years ago) that the top sight glass valve was leaking air....something to check if you have a sight glass.... and many years before that, learning (from reading here on the wall) that the auto air vent should not be in the system.

    Just a side note on that 1961 (date code of 1960) compression tank....how many bladder tanks would we have gone thru in 62 years?

    Hopefully I did not curse it and have a leak....once the air problem is resolved I may drop the pressure below 20 PSI.
  • leonz
    leonz Member Posts: 688
    edited January 14
    Hello JUGHNE,

    I can relate to this. When I was driving myself a bit crazy over my massive vacuum problem and low pressure in my system from a past seasonal shut down, I did detective work isolating and eliminating possible problems until I at last came to the sight glass tube and the valve packings.

    I tightened the packing gland nuts on my steel compression tanks water tube sight glass 1/4 turn and that solved it. I made sure I shut the globe valves off before I tightened down the gland nuts 1/4 turn to avoid damaging the valves.

    If I had a larger steel compression tank greater than 15 gallons it probably would never have become a problem.

    When the house had an open to air saddle tank (which I now know I should have kept) I never had vacuum or air slug problems.
  • RayWohlfarth
    RayWohlfarth Member Posts: 1,073
    Thanks @JUGHNE We finally got the air out. The installer must have been a roller coaster fan and the pipes go up and down all over the building.
    Ray Wohlfarth
    Boiler Lessons
  • mattmia2
    mattmia2 Member Posts: 7,216
    Maybe put a purge station in each zone after the zone valve so you can purge between the station and the return with a pump cart and not get the restriction from the zone valve.
  • jumper
    jumper Member Posts: 1,915
    When I could I'd put suction on system before filling. Also try to fill to MINIMUM. Intention is to let air accumulate at top where I can evacuate with suction. Of course somebody eventually over fills or installs automatic valve and then my plans come to naught.
  • hot_rod
    hot_rod Member Posts: 18,279
    This make getting and keeping air out more of a challenge.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • RayWohlfarth
    RayWohlfarth Member Posts: 1,073
    @mattmia2 I would have loved doing that and in hindsight, I should have
    @jumper Thats a good idea. I will try that
    @hot_rod Thats about it. I am installing Caleffa automatic air vents on the coils. I love that they have a check valve so they can be replaced without draining the system
    Ray Wohlfarth
    Boiler Lessons
  • hot_rod
    hot_rod Member Posts: 18,279
    Thanks for the Caleffi choice.

    Here are a few other handy accessories. The hydroscopic cap is an extra protection, should the needle valve ever get plugged or stuck.

    The anti siphon cap is a good troubleshooting cap, should you suspect air is being sucked in. It will still vent air out
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • RayWohlfarth
    RayWohlfarth Member Posts: 1,073
    Thanks @hot_rod I will look into those I bought the 5027110 and will let you know how they work

    Ray Wohlfarth
    Boiler Lessons
  • leonz
    leonz Member Posts: 688
    edited February 3
    I am glad I removed all of my automatic air vents as they were more trouble due to leaks than they are worth.

    I have a Fifteen Gallon B+G/Wessels Tank Company Steel Compression Tank and I never ever have to crawl around on my replacement artificial knees to deal with trapped slugs of air as there is none to affect the system.

    I wish I still had my saddle tank mounted open to air expansion tank as it would be even simpler to live with.
  • RayWohlfarth
    RayWohlfarth Member Posts: 1,073
    @leonz How are you doing that? I take it the pump is on the supply and pumping away. What happens if you have to drain the system?
    Ray Wohlfarth
    Boiler Lessons
  • leonz
    leonz Member Posts: 688
    edited February 4
    Hello and good evening Ray,

    I have not had to drain the system since I repaired what the clowns I hired to install the coal stoker did to it.
    If I ever have to drain it will be very easy refill and vent the air from three points being the highest pipe in the ceiling the boiler drain in the top of the module (thank you Dan) and the airtrol valve as I will only need 54 gallons of water+-.

    my single B+G NRF 25 circulator is above the boiler pumping away in a pump module and has isolation valves and a vacuum gauge on the inlet side and a pressure gauge on the pressure side(thank you Dan).

    My 225 foot length of 3/4 copper fin tube baseboard single loop is on the ground level.

    If I ever have any air at the start of the heating season which is very seldom it is at the highest point where the genius I bought this place from 45 years ago ran 3/4 copper pipe overhead to an elbow with vent key that goes straight down into the floor and then under the wall to the first length of baseboard in the loop.

    I have the vent key attached to nylon twine so if it slips out of my hand it only drops a couple of feet-I learned that lesson the hard way misplacing vent keys.

    If I have a slug of air its usually before the elbow where the vent key is from being shut down from late May to October.

    Most years I fire up the coal stoker late and turn the heat way up and the raise the aquastat high limit and the microbubbles waddle a little faster than I do to the Internal Air Separator (thank you Dan) and and rise into the Airtrol valve and then into the steel compression tank (thank you Dan and The Dead Men).

    When the system had the open to air expansion tank in the laundry room ceiling we never had to touch it and as I have said before knowing what I know now I would have never let them remove it in 1982 and it would still be there today.

    We do not have the use of the domestic coil now as they screwed that up too-the propress fittings blew off the fittings they installed in the coil tappings (it drained my well during the night 6 years ago) and I had over 100 gallons of water in the laundry room floor, I am just glad the pump control kicked off as it would have burned up another $500.00 deep well pump.

    I need to fix the coil connections with stainless steel woven washing machine hose and bib fittings when the heating season is over as they did not install 4 brass unions sweat to short lengths of copper to allow flushing the coil with vinegar of changing of the coil.

    It is so much easier to live with a hot water heating system that is sealed off from the water supply.

    My old house leaks a lot of heat and is poorly insulated the only way to keep up is with a coal stoker boiler.

  • RayWohlfarth
    RayWohlfarth Member Posts: 1,073
    @leonz Thanks that explains it Sounds like you know your system well
    Ray Wohlfarth
    Boiler Lessons