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Still Got Air-

ced48
ced48 Member Posts: 469
I have been fighting air in a Lochinvar WH55 indirect loop for a year now-I even added a Spirovent to the loop, it removes the air, but not before the annoying noise comes from the HX. No, it is not flashing, it is air. I have raised static to 18 pounds, finishes cycle around 20+. Will run quiet for weeks, then air shows up near end of cycle. In the past, raising the pressure makes her run quiet for a while, but then the air returns. I don't want to raise pressure any more-There are no leaks. There is an air removal valve in the outlet line, factory installed, could it be pulling in air? Has anyone ever had this problem? This is driving me crazy-

Comments

  • Zman
    Zman Member Posts: 7,559
    I was looking through your posts.
    No pictures...
    Maybe post some pics and see if someone sees something you are missing.
    Kind of sounds like pumping the wrong way. What model are the circs.

    Carl
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • ced48
    ced48 Member Posts: 469
    The Bumblebee is gone, both circs are Grundfos 15-58's-
  • ced48
    ced48 Member Posts: 469
    Here is another photo-
    loch.jpg 129.7K
  • icesailor
    icesailor Member Posts: 7,265
    edited October 2014
    Nice clean piping job.

    Is that a #15 Extrol? Are you sure that that is big enough? Do you have a #15 or #30 that you can adapt and connect it to any place in the system with a double washing machine hose as a temporary test to see if it stops? Something I have done in a pinch. How much water is in the system? If it has Antifreeze in the system, I thought they needed more expansion allowances.

    15-58's are 3 speed pumps. Have you tried slowing the secondary pump down or the primary down? According to the Grundfos pump curve, you can push a lot of water on high speed. Maybe more than you need. Causing cavitation somewhere in the system.

    I've turned a lot of those #15's to low speed (#1 speed) and they worked just fine.

    JAT.
  • ced48
    ced48 Member Posts: 469
    JAT Thanks for the compliment on the piping-Yes, it's a #15, 2 gallon. System is very small, and should only need about a quart of room for expansion. However, I have always questioned it. Your idea of adding another tank with a washing machine hose is excellent, and I will give it a try
  • icesailor
    icesailor Member Posts: 7,265
    edited October 2014
    Its worked for me for years.

    A true shade tree temporary repair.

    With a "rig" made of 1/2" bl. nipples, a air hose adapter on one end, the other with a boiler drain, and a 50' air hose, connected to a portable air compressor, there isn't much you can't do as far as testing and draining. I always had a collection of WH hoses in the truck for such purposes.

    If yu have an old boiler with a tired fill valve, a 6' WM hose as a back feed into the boiler is a wonderful thing. Time is money. It can save a lot of time filling a large heating system.
  • Ironman
    Ironman Member Posts: 7,363
    I'm not a fan of using Sharkbite fittings on hydronic systems though I've been guilty of it in a pinch. The possibility of air entering at the o ring is always a concern. And yes, it can happen even though there may be no water leak.

    I'd also recommend checking the unions on the HX for tightness.
    Bob Boan
    You can choose to do what you want, but you cannot choose the consequences.
  • Ironman
    Ironman Member Posts: 7,363
    Another thing: I installed a lot of the WHNs and something I've begun to do is add a small auto vent next to the relief valve above the HX. You'll need a 3/4" black Tee, a 3/4" street 90 and a 3/4 x1/8" bushing.

    TT and ECR both supply these fittings and vent with their wall hung boilers. Maybe Lochinvar will catch on to it also.
    Bob Boan
    You can choose to do what you want, but you cannot choose the consequences.
  • ced48
    ced48 Member Posts: 469
    edited November 2014
    Icesailor-around 3:00 AM this morning, I started thinking about your circulator thoughts. I have been running DHW at medium speed, 65% firing rate. I came to this combination after doing the math with the info provided by HTP-I reduced the firing rate to quiet the unit down a little as it is in my den. I had tried running low speed at full fire and began to get early signs of "flashing", so I went back to medium, Taco 007 equiv., speed. Around 3:30 AM, I remembered cleaning a bunch of teflon tape and pipe goo from the system strainer. Well, to make a long story short, I had to run the circ at medium because of the restriction in the strainer. Once cleaned, I was over pumping the loop, probably by double. I am pretty sure this was causing turbulence, which in turn was causing air separation. Also, HTP's guidelines for head are a bit overstated. I have only run two cycles, but have that great gut feeling that this was the issue. Thank you so much JAT, and Carl, for mentioning the circulators. Fingers crossed that this mystery is solved-

    Bob, I would rather not use Sharbite fittings either. I used them to make the boiler connections because of Lochinvar's recommendations-
  • icesailor
    icesailor Member Posts: 7,265
    edited November 2014
    That brings up an interesting experience that I had. I installed a Noritz commercial tankless water heater and connected a storage tank to it because the tank was already there. The thing didn't work as I expected. There is a small filter in the cold inlet to the Noritz. The circulated water from the tank was pumped through the cold on the Noritz and through the filter. When I started the unit, the burner ran wide open. Later, when it didn't produce the expected hot water, I noticed that the burner blower motor never ran any faster than medium speed. It would never run on high. Because, debris in the municipal water would plug the filter, and cause the burner to slow down. I needed high flow, but it was restricted through this filter. I had to install a Cuno 110 stainless hot water canister filter to trap this black stuff that was coming from the municipal water system. They wouldn't believe it until I showed them the contents of the canister and filter.

    With any of these Tankless Water heaters that are on demand/indirect, if that inlet strainer slows down the flow, the water in the coil will get hot and the burner will slow down. Cutting down on the hot output. I had it piped in such a way that ALL the water that went in to the heater, went through the storage tank first and then through the Cuno filter. If you know the internal filter, it isn't much of a filter. If you are having flow problems and the burner doesn't run properly, check that filter. I've seen them all plugged up from poorly developed wells where they didn't get all the fine sand or drill mud out when they developed the well.

    Something to be aware of.
  • Zman
    Zman Member Posts: 7,559
    Hope that solves it. The problem of turbulence is made made worse by the space constraints of your install. If you had enough room to get the minimum pipe diameters on the circs and air eliminators your air issues would be improved.
    Bob's comment on the boiler air eliminator is right on. The fire tube exchanger itself is a great air remover, it should have a vent.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • ced48
    ced48 Member Posts: 469
    edited November 2014
    The boiler does have a factory installed air vent/valve on the supply line. All my pipes/connections are the proper size, none are reduced, and they are all spaced to minimum spacing requirements-The boiler/DHW tank are in a 36" x22" space, I did the best I could, and I think it will be just fine-working on the system is not bad at all, as I used lots of unions, ect
  • SWEI
    SWEI Member Posts: 7,356
    I have had almost no air issues with the TT HX design -- so few that on the most recent system we installed (cascaded pair of PTS250's plus a PTS110 for a separate building and the indirect.) I did not use any air elimination devices other than those provided with the boilers and the indirect. I figured I could add one to the top of the DirtMag if we had issues, but that proved not to be necessary.
  • Zman
    Zman Member Posts: 7,559
    I get the space issues. I hope I did not sound critical.
    Systems perform better when air eliminators are not butted up to circulators.
    Your workmanship is quite good.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
    RobGBobbyBoy
  • icesailor
    icesailor Member Posts: 7,265
    @CED48:

    This is my personal opinion.

    Can you get that top off of the air elimination device and remove whatever is in there as a temporary try? I could be wrong, but it appears to me that the circulator pumps IN TO the air eliminator and in to the boiler. It is my firmly held belief that the material design in the air eliminator can cause serious cavitation in the flowing water.

    Also, those Schrader valve caps. Go to a auto supply house and get some metal ones. Those plastic ones can leak air. Even when down tight. I just have never seen the air bound problems in my own personal experience as I see here. I had so few problems that it came to the point that the only reason I put air vents on baseboards was to shut up critics. O started using "Jet Tee's
    with caps on one end of baseboards. I'd grease up the caps when I installed them to keep them tight. I never touched them again. If the red and black caps have O-Rings in them, grease them up with some silicone grease and tighten them for a trial.

    Eliminate that air elimination device as a source of air. It might be there.
  • ced48
    ced48 Member Posts: 469
    The air eliminator is on the suction side, and circulator is- pumping into the boiler's return
  • ced48
    ced48 Member Posts: 469
    The circulator is bolted directly to the air separator-This arrangement is a Watts design that I trusted was okay-