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Added ESBE valve, now have an air problem

I changed my near boiler piping from being hooked straight up to my old gravity pipes to primary/secondary by adding a second circulator and an ESBE valve, with the goal of getting return water temp up to where it should be.

It worked like a charm, the boiler rockets up to about 160 and then the ESBE starts letting return water in. Once that starts, though, the boiler loop's circulator starts sucking in air and making a ton of noise that reverberates through the pipes and radiators. By the end of a long heat call it mostly subsides - I assume because the ESBE is mostly open due to return water being hot enough. But then on the next heat call it starts all over again which I don't understand, because it seemed to get the air out of the pipe by the end of the previous run!

The air seems to be between the first closely spaced tee and the inlet of the ESBE. The "house" loop of the old gravity lines isn't moving any air around. The boiler loop doesn't start making any air noises until the ESBE starts to open.

I hope it's something as simple as needing a fitting with an air vent and that I didn't screw this up somehow. See the attached pictures. I feel like I did this mostly right because I did a ton of research before starting, between this forum and Dan's books Classic Hydronics and Primary/Secondary Made Easy. Thoughts? (And PS - I know it shouldn't be Romex going to the circs but my hardware store was out of armored cable by the foot and I didn't want to buy a huge roll. I'll be going back in to change that...)



Comments

  • Is your system pump - the black one - pumping towards the closely-spaced tees?

    Where is your expansion tank located?

    Cool twin ell and wye fittings. They're drainage fittings, but who cares?
    Often wrong, never in doubt.
  • gardenweasel
    gardenweasel Member Posts: 24
    Ha! I inherited those, just the shiny stuff is what I did. Yes, the black pump is pumping towards the closely spaced tees and away from the expansion tank which is in the rafters above. The green Wilo pump on the boiler is pumping toward the side return.

    The system used to flow the other direction but I reversed it to pump away from the expansion tank. It worked fine before though so if I should reverse the black pump it would likely be no biggie.
  • Zman
    Zman Member Posts: 6,430
    What model WILO?
    Do you have the specs for the ESBE?
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • gardenweasel
    gardenweasel Member Posts: 24
    The WILO is a Star 21FX on the middle speed. The lowest wasn't enough flow and the boiler would shut off on high limit so it seems medium is about right. High just makes more noise.

    The ESBE is a VTC511, 1", with a 140 degree thermostatic element in it.
  • Zman
    Zman Member Posts: 6,430
    edited December 2018
    Well, you have a first class puzzle.
    You have a compression and therefore no air eliminator? Is the tank setup correctly? What is system pressure? Do you believe your gauge?
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • For your safety, put some copper pipes on the pressure relief valve to discharge it 12 inches from the floor.—NBC
  • gardenweasel
    gardenweasel Member Posts: 24
    It's an old school expansion tank, possibly the original - up above the boiler in the rafters. I do not have an air eliminator but before I made these piping changes I've never found one to be necessary. Any air in the lines would end up in the 3rd floor radiators in a couple days and I could just vent it out.

    The pressure is about 20 psi and I think I believe my gauge (it was just replaced, along with the safety blowoff valve.) I just filled the system until I got water all the way into the 3rd floor radiators and no further.

    Here's the tank and the piping to it:

  • neilc
    neilc Member Posts: 1,205
    yeah, you really can't run a compression tank off the side of that vertical line and get "air separation". it might work off the top of a scoop, or dirt mag type spiral separator, and it will deal with pressure there, but you have no air removal like that cause it won't go sideways to do that.
    That tank is supposed to accept air, but it has to come from the top of a high spot or scoop, and the line to the tank needs to pitch up the whole way.
    you could abandon the compression tank and plumb in a sized bladder tank there. And you still need to add a scoop and air vent somewhere.
    or you need to properly plumb that existing tank to a top of scoop.
    What ever you do, keep pumping away(from the tank).
    DZoro
  • neilc
    neilc Member Posts: 1,205
    and looking again,
    Looks like you built a flow thru compression tank there.
    Are you still pumping towards the old larger connection,
    and thinking you're pumping away where that small line ties in before the circ?
    that won't work as intended.
    Your pulling air out of the tank, entrained air, thru the 1/2 inch line.
    You don't want that circulation thru the tank.
    Where is that larger original connection, connecting? can't see it from pictures. Is it still connected?
    DZoro
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 8,496
    Hard to see all the expansion tank piping but I think @neilc is on to something. I think your pulling air out of the expansion tank into the system etc.
  • gardenweasel
    gardenweasel Member Posts: 24
    Both connections of the tank are still connected and on the same side - and we're definitely pumping away right now. There's an old black iron connection and a 1/2" copper connection going into a tee with the makeup water line. I see what you're saying, that maybe the tank spanned the supply and return sides, but they're definitely both on the return.

    Before I changed any of this though, the circulator was pumping toward that tank. I changed it to pumping away because it's what everybody says is preferable.

    I tried to get a better picture but the angles are tough with pipes going everywhere.

  • gardenweasel
    gardenweasel Member Posts: 24

    For your safety, put some copper pipes on the pressure relief valve to discharge it 12 inches from the floor.—NBC

    Thank you! That's actually on my list to do, I just have to get the parts.
  • gardenweasel
    gardenweasel Member Posts: 24

    Hard to see all the expansion tank piping but I think @neilc is on to something. I think your pulling air out of the expansion tank into the system etc.

    If I was pulling air out of the tank I'd think it would hit the Taco (black circulator) first and I'd hear it grind in that pump. If I turn off the green Wilo all the noise stops.
  • Matt_67
    Matt_67 Member Posts: 193
    It seems odd to me that speed 1 wouldn't move enough water through the boiler loop. Any chance there is a restriction in ESBE return water connection? I've installed those but can't remember if there is a screen anywhere there. If that connection was restricted it could make the pump cavitate which sounds somewhat like air in it.
  • DZoro
    DZoro Member Posts: 1,047
    With the original flow direction the entrapped air from the boiler and the system had a quick and easy exit to the tank. As you are piped now, the air from heat of the boiler and system has no choice but to travel the entire system and back down to the return, then maybe get a chance to hit your vertical tee and go to the tank.

    Like @neilc said, it could actually be pulling air from the tank.

    I haven't seen the previous piping, but IMO if you want to keep the old tank, you will have to move it and the pump to the supply side.
    Or put in a extrol tank and air separator.
    D
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 8,496
    As the expansion tank has two connections to the system any pressure drop (and there will be some) between the two tees at the expansion tank connections will cause flow through the expansion tank.

    This is not what you want. The flow will pull air into the system. The expansion tank needs to be on a "dead ended" connection to the system, a "quiet" connection where air can bubble up through the water. The expansion tank piping needs to be short and direct and off the top(not the side) of the system piping preferably connected to an air scoop.

  • Gordy
    Gordy Member Posts: 9,530
    edited December 2018
    I agree with the above conclusions. One pipe to compression tank, and into top of secondary piping.

    Usually the ci boiler has a built in baffle to trap air on the supply port. When the boiler is off it allows that air to flow back up in the compression tank, this is if you don’t have a separator.

    If the piping to the compression tank isn’t direct, and pitched to the tank the air has to take the long way around ending up trapped in emitters before it gets back to the tank. Then you bleed the emitters add more water, and before you know it the tank is water logged. Think like air, and where the easiest route to get to where you are suppose to be.
  • neilc
    neilc Member Posts: 1,205
    looking at that last picture puts you in a little better position, not as flow thru as I thought, but like Ed said, there is likely still a flow there, and there should be just one line up to the tank as Gordy writes.
    How do you service, drain, check, that tank?
    I think I would abandon the new 1/2 inch line to the system, and use that as a tank drain as that port was intended.
  • kcopp
    kcopp Member Posts: 3,657
    May be better off in the long run to convert the system to a closed diaphragm expansion tank and a proper air separator. Personally I like the Caleffi Discal.
    Zman
  • Paul Pollets
    Paul Pollets Member Posts: 3,366
    I'd replace the existing expansion tank with a 60g pre-charged Extrol and install a Spirovent and a thermometer. The existing "near boiler piping" is not ideal.
  • Steamhead
    Steamhead Member Posts: 14,324
    No need to replace the tank. That would be a waste of money, and going to a bladder tank would add another service issue since bladders fail over time.

    Use a good air separator such as a B&G EAS. This unit can accommodate an air vent or an expansion tank connection on top:

    http://documentlibrary.xylemappliedwater.com/wp-content/blogs.dir/22/files/documents/2012/02/A-600A.pdf

    Run a single 3/4" pipe from the air separator to the tank, and install the proper Airtrol tank fitting where the pipe connects to the tank. This will vary according to the tank diameter. See page 10:

    http://documentlibrary.xylemappliedwater.com/wp-content/blogs.dir/22/files/2012/07/A-307B.pdf

    This will route air from the separator to the tank, maintaining the air cushion so the tank will not waterlog.

    This setup is a bit more expensive than a bladder tank, but it just works and you hardly ever have to mess with it. I also like to use a tank drainer instead of a boiler drain on the tank. This speeds up the process if the tank ever needs draining.
    All Steamed Up, Inc.
    "Reducing our country's energy consumption, one system at a time"
    Steam, Vapor & Hot-Water Heating Specialists
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    Solid_Fuel_Man
  • gardenweasel
    gardenweasel Member Posts: 24
    Thank you everyone! As an update, this weekend I flipped the Taco circulator to pump toward the tank like it used to (I know, I know). That actually seemed to help. The air is mostly purged from the boiler loop and isn't returning. There are a few air pings upon startup and when the ESBE opens but they're lessening with each heat cycle.

    Also: I was able to drop the Wilo pump to speed 1 and the boiler no longer goes off on high limit so maybe it was just because of all the air that speed 1 couldn't keep up.

    I have no idea why that expansion tank was piped the way it is but the more I learn from you all the less sense it makes.

    I do intend to incorporate the suggestions here and I really appreciate everyone's time and thoughts. I just have a bit of boiler fatigue right now and if I can get away with not draining my 3 story house again it would be nice.
  • Zman
    Zman Member Posts: 6,430
    Your primary/secondary is piped backwards now, yes?
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • gardenweasel
    gardenweasel Member Posts: 24
    Yes. Doesn't seem to be causing a problem though - there's more water flowing through the house loop than the boiler loop and it makes for a nice mixing action. All the radiators are still getting evenly hot through the house and it doesn't seem any slower than before I added p/s.
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 8,496
    I would still make the changes when the weather warms up.
    DZoro
  • Solid_Fuel_Man
    Solid_Fuel_Man Member Posts: 2,252
    I posted a few years back on a large commercial job where there were 3 injection loops feeding slab radiant from two high temp Smith boilers. All 3 were piped backward and had been that way since 1996! I proposed repiping the job but the building super refused (which I could understand). The Tekmar house controllers all seemed to ramp to normal levels too!
    Serving Northern Maine HVAC & Controls. I burn wood, it smells good!
  • gardenweasel
    gardenweasel Member Posts: 24
    Another update: I reversed the tees so the p/s isn't pumped backward anymore, as well as angled the approach to the ESBE valve so there isn't a horizontal run that could potentially trap air. And I STILL have a noisy boiler! I feel like there's a finite amount of air here and once it's gone it should be gone but every heating cycle this problem returns.

    Here's the whole process: thermostat calls for heat, boiler and both circulators turn on. The boiler rapidly gets up to temperature, and until it reaches about 170 on the gauge it's quiet and smooth sailing. Once it hits about 170 the Wilo pump on the boiler loop starts sucking in air, which then has trouble leaving because the ESBE valve isn't fully open and it's just firing around the boiler loop over and over. Once the ESBE fully opens near the end of a long cycle the drama stops.

    I'm starting to regret ever messing with it. My only idea is to put a Taco air scoop on the boiler loop so it purges the air that gets in there - but I see in the directions that it wants 18" of straight pipe before the scoop and I don't have that available. Would it have a chance of still working anyway?
  • Zman
    Zman Member Posts: 6,430
    What pressure are you running? Is there more than one gauge so you can verify?
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • gardenweasel
    gardenweasel Member Posts: 24
    edited January 2019
    No I just have the gauge on the boiler itself (which was just replaced, the original one was toast.) It's about 16 psi cold and 20 fully hot. Edited to add: this is a 3 story house so 16 is about the minimum I could do to get the 3rd story radiators full.
  • hot_rod
    hot_rod Member Posts: 14,552
    I'd add a Discal air sep just past the closely spaced tees, add a #60 Extrol and be done with it.

    Those small entrained air bubbles are tough to get out with the air removal system, or lack of, that you have now.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    ZmanDZoro
  • gardenweasel
    gardenweasel Member Posts: 24
    Final update: I threw a Taco air scoop on the boiler loop right before the ESBE, and that did the trick. The air just couldn't get out of the boiler loop and now it just gently hisses out the hy-vent with no drama. It works fine despite not having 18" of pipe before it.

    Thank you to everyone for your time and suggestions.
  • kcopp
    kcopp Member Posts: 3,657
    The problem now it that the hy-vent is in the system w/ a conventional compression tank. That tank now has a good chance of water logging.... That air is supposed to go back to the tank.
    GordySolid_Fuel_ManCanucker
  • hot_rod
    hot_rod Member Posts: 14,552
    Add a tube to the vent connection on that scooping run it up to the compression tank or you will slowly but surely lose that air bubble in the tank.

    A compression tank is an "air management" system. You now have an air removal system, either change the tank to a diaphragm type to have a captive air bubble, or vent the air into the current tank.

    Here is an example on my solar drainback system, it maintains an air bubble at the top of the tank the same way.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    Solid_Fuel_Man
  • Solid_Fuel_Man
    Solid_Fuel_Man Member Posts: 2,252
    Bob is 100% correct.
    Serving Northern Maine HVAC & Controls. I burn wood, it smells good!
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