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circulater after air vent

quack24quack24 Posts: 62Member
edited February 2016 in THE MAIN WALL
hey guys need some help with a hot water baseboard system its a 3 story building with 1 1/4 baseboards system pressure is about 30 psi boiler is in basement the problem is this: on the third floor the pipeing goes into the ceiling to make it over the hallways (in 2 places) in one of those places is an automatic air vent and about a foot or so downstream is a 007 circulator the circulator makes an awful lot of noise leading me to believe the air vent is letting in air every time the circulator turns on my proposed solution is to replace the air vent with this http://www.supplyhouse.com/Caleffi-502015A-MINICAL-High-Capacity-Automatic-Male-Air-Vent-1-8-NPT and this http://www.supplyhouse.com/Caleffi-562100-Anti-vacuum-Air-Vent-Cap any suggestions or criticism will be greatly appreciated
thanks

Comments

  • quack24quack24 Posts: 62Member
    forgot to mention there is always air building up by that "hump"
  • GordyGordy Posts: 9,263Member
    edited February 2016
    Your assumptions are correct.
  • hot_rodhot_rod Posts: 11,252Member
    30 psi at the boiler? What type of relief valve?

    That is a tough spot for the circ to be installed. Be sure the pressure gauge is accurate, you want 5 psi at that highest point in the system for a float vent to seal tightly.

    That float type air vents work best at high points where air will normally rise up and trap. They are not ideal for pulling air out of a pipe as it flows past. There is not much to encourage air to find the vent opening :) Any way to add a tee and create a high point nearby?

    A Discal would be another option, it would create a wide spot for air to collect and offer the media inside to grab micro bubbles.

    Worth a try, add the anti siphon cap along with an "Aquastop" cap for extra protection against discharge.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    The magic is in hydronics, and hydronics is in me
  • aircooled81aircooled81 Posts: 194Member
    where did you read system pressure btw?
    is the water make-up located on the first floor or basement? 30psig make-up water can achieve 69 feet of head. is your attic space where the pump is located 68 feet above the make-up water? not likely...
    air entrained in a hot water loop seperates itself best at high temp and low pressure. your pump in the attic is the point where the pressure is lowest in the system, and the air entrained in the water wants to seperate. The pump naturally lowers the pressure at the suction side.
    So the pump can pull down the pressure on it's low side, and if it pulls it down low enough, I have see hoffman's suck air back in. kind or peculiar to install a pump at the top of the loop. but hot rod is right, these type of airvents are not exactly for removing air like this application requires, inline air separators provide better air removal.
    I would pull the auto air vent off and throw a guage on its port, turn the 007 on and see what the pressure is there. then I'd determine if A) am I pulling a negative pressure do to some blockage upstream B) can I afford to lower my pressure and help air seperate easier elsewhere in the system.
    if you can not move the pump, can you install an air seperator where the auto airvent resides?
  • GordyGordy Posts: 9,263Member
    If the piping is in the ceiling of 3rd floor, and boiler in the basement. Gauge at 2 feet off floor figure 35 feet @ .43 psi per foot so 15 psi plus another 5 to get over the top. 20 psi is plenty.

    Jacking up the psi higher does keep air in solution better provided the pressure relief valve does not pop off.

    Apparently this boiler was fitted with a higher psi rated prv
  • aircooled81aircooled81 Posts: 194Member
    good point gordy,
    to consider when the delivery of the make-up water to the 3rd floor ceiling (make-up water prv setting), if it is to enter the pump up there, should additional pressure be added to account for the pump suction bringing the pressure down, once the water has reached the high point of the system?

    i also wonder if this ceiling pump is the only pump in the loop, or was an addition to a pump down in the basement. basically when you have two pumps in series, does that increase the gpm or the ft of head?
  • GordyGordy Posts: 9,263Member
    Odd location. To say the least. I get the air vent not the circ.
  • SWEISWEI Posts: 7,356Member
    Is the pump truly in series, or is the top floor loop hydraulically separated from the rest of the system?
  • quack24quack24 Posts: 62Member
    thanks everyone for the input sorry for not replying sooner here is the story its a commercial building and the third floor was added at a later point so they made a loop off the second floor baseboards with 2 tees spaced about a foot apart so its probably hydraulically separated "enough" the main loop has a big circulater not a wet rotor one
  • quack24quack24 Posts: 62Member
    im thinking about putting some sort of fitting by the air vent tee with a dawn soap auto feeder to get rid of the air
  • quack24quack24 Posts: 62Member
    the air vent is on a tee maybe i should add a nipple to raise it up higher
  • hot_rodhot_rod Posts: 11,252Member
    quack24 said:

    im thinking about putting some sort of fitting by the air vent tee with a dawn soap auto feeder to get rid of the air

    quack24 said:

    im thinking about putting some sort of fitting by the air vent tee with a dawn soap auto feeder to get rid of the air

    Soap is a last ditch effort in my mind. Continually adding soap will change the fluid quality and excessive soap may foam. It's better to rid and prevent air with proper piping and removal devices.

    Bob "hot rod" Rohr
    trainer for Caleffi NA
    The magic is in hydronics, and hydronics is in me
  • quack24quack24 Posts: 62Member
    i was only kidding but someone should come up with an automatic low soap feeder
  • hot_rodhot_rod Posts: 11,252Member
    Larger commercial systems will often have a "pot feeder' in the piping. It is for adding treatment and conditioners.

    Glycol in dirty piping systems can have a tendency to foam, there are defoamers that can be added for that problem. Foaming is different from a rouge air problem like you are describing,

    Adding an anti siphon cap as shown a few posts up may help and it would tell you if air is being pulled in at that vent location.
    It's a $5.00 fix, many times :)
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    The magic is in hydronics, and hydronics is in me
  • quack24quack24 Posts: 62Member
    for now i put the anti vacuum caps from callefi well see if they solve the problem do you know if any other company makes a similar device? does anyone have any experience with those caps. I put them on two days ago and the circulator seems a lot quieter so im guessing its doing the trick for now does anyone know when these things start failing? is it a once a year type of thing or do they have a longer lifespan
  • hot_rodhot_rod Posts: 11,252Member
    quack24 said:

    for now i put the anti vacuum caps from callefi well see if they solve the problem do you know if any other company makes a similar device? does anyone have any experience with those caps. I put them on two days ago and the circulator seems a lot quieter so im guessing its doing the trick for now does anyone know when these things start failing? is it a once a year type of thing or do they have a longer lifespan

    It will be like any other "wetted" hydronic component, fluid quality, dirt specs, aggressive ph, number of cycles, etc all determine the life cycle.
    I like to add the hygroscopic cap so IF or when it fails, you have another shut off mechanism, especially if it in a location that could cause damage from a drip.

    I think you know it is a bandaid, treating a symptom not the problem. I suggest installers use them until a permanent fix can be found. On a large system it may need to wait until summer or down season to do major surgery.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    The magic is in hydronics, and hydronics is in me
  • quack24quack24 Posts: 62Member
    i understand its a band aid but the building owners arent really willing to spend the money and we will probably only be here for one more year
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