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Boiler Heating System: Bleed Air from Zone

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cbodary
cbodary Member Posts: 11
I've read several discussions concerning this topic and I've tried following the instructions given, but I'm still struggling. I have a Weil-McClain Gold GV boiler with two heat zones. I believe the unit has a single circulator. Zone 1 has heat circulating normally. Zone 2 is not circulating heat correctly.

I suspect there may be air in the zone preventing hot water from circulating. I've tried to bleed the zone using different combinations of valves open, valves closed, etc., but I'm still not getting heat circulating correctly.

The first baseboard register in line (located ~ approximately 10' away from the boiler) is hot, but the remaining registers in the zone are not. I do not have bleeders on my baseboard registers. The outgoing line is HOT. The return line above the drain valve is not.

What is the proper way to isolate Zone 2 to ensure I'm bleeding air out of it properly. IE., What valves should be closed and which should remain open? Could my described symptoms have a different root cause? Thank you in advance.



Comments

  • Jellis
    Jellis Member Posts: 228
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    1. shut off power to system
    2. close zone 1 supply and return valves
    3. close zone 2 return valve
    4. attach hose to drain valve above zone 2 return ball valve.
    5. increase the pressure in the boiler to 20-25psi
    6. open drain valve and let water flow through zone 2 loop, you should hear air leaving the drain hose as you purge the zone.
    you need to "push" the air out of the line, if you think about it the air wants to rise to the highest point in the piping system so chasing the bubbles down sometimes takes a little time.
    you can adjust your water feed valve to feed 20 psi if dont want to play with the manual feed, just dont forget to adjust it back.

    you could have other issues causing this as well, have you heard any sounds coming from your pipes recently?
    if you have been hearing "rushing water" in that zone then that would be a sign that it became air bound. if its been quiet then you could have a faulty zone check or circulator. More pictures of your system could help if bleeding doesn't work.
  • cbodary
    cbodary Member Posts: 11
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    Thank you for the response. I've done as suggested.... ran approximately 20 - 25 gallons of water through the zone. A good portion of the water was pretty dark in color, but cleared as I progressed.

    Nearly every time I closed the drain to let pressure build, and then opened it back up, I would get more air. It's been two hours since I opened everything back up and restored power to the boiler, but I'm still getting heat to just the first register in the zone. The copper going into that register is hot... the copper going out of that register is just warm... noticeably cooler than going in.

    I still have to believe the issue is "air". The circulator is pushing hot water through zone 1 with no issues. I think I will try bleeding zone 2 again, but this time I will run the hose to a bathtub rather than go back-and-forth with a 5 gallon pail. Here are additional photos. The one with the register circled is the one that I am getting some heat to. You can see how close it is to the heating system.





  • SuperTech
    SuperTech Member Posts: 2,186
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    Make sure you close the ball valve below the drain while purging. It won't work any other way.
    cbodaryGrallertrick in Alaska
  • HomerJSmith
    HomerJSmith Member Posts: 2,467
    edited February 2020
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    No flow, no heat! I not sure that you even moved purge water thru zone 2. What I am thinking is that the Honeywell zone valve isn't opening. You can manually open it by moving the lever under the black terminal block on the valve and setting the lever in the detent position, which keeps the valve from closing and in open position. If there is a call for heat on that valve, the lever should slide from left to right easily. If the valve is closed the lever would slide from left to right with difficulty as you would be pushing against the spring that closes the valve when no power is going to it.

    Try that.

    If that works and the valve wasn't open, then the problem is in the thermostat controlling zone valve 2, the wiring between the zone valve and the thermostat, or the zone valve motor which is easily replaced.

    Why do you think zone 2 is air bound if it worked previously?
  • cbodary
    cbodary Member Posts: 11
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    My assumption of the air lock is based on everything else "working" as best I can tell. I have heat, the thermostat is calling for heat as it should (it's close enough that I can hear the zone valve close when I turn the thermostat off), the circulator is pushing hot water through zone 1 with no issues, etc.

    I'm not sure how I could NOT have had water flowing through zone 2 while purging... especially in my last attempt. Both zone 1 ball valves were closed, the ball valve for the zone 2 return (below drain valve) was closed, and I alternated the water feed valve open/closed to maintain a pressure between 20 and 30 PSI while I left the drain valve open. I ran this purge for approximately ten minutes continuously.

    The zone valve lever for zone 2 moves back and forth freely. I've had it positioned on manual/open the past few days. This zone valve was replaced new just over one year ago.

    I've considered a frozen line, but that is extremely unlikely. The zone is contained within insulated space, the temperatures outside have been moderate, and the lowest I've seen the temperature inside this space is 57 degrees. I've considered the circulator may not be working at 100% so I closed zone 1 in order to isolate zone 2... thinking perhaps the circulator may be able to service just that single zone. With zone 1 closed the hot water being circulated should push through zone 2. No luck.

    I'm stumped.
  • Jellis
    Jellis Member Posts: 228
    edited February 2020
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    Your zone valve is sounding more like the culprit to me.
    you say the zone valve lever moves "freely"
    it should have resistance when opening the valve to manual open. If the lever just flips around loose like, than its likely not engaging.
    compare the action of the valve with the other zone valve and see if they are the same.
  • cbodary
    cbodary Member Posts: 11
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    I will compare the move-ability of the two zone valves as soon as I get home this evening. The zone valve for the zone I'm struggling with definitely gives very little (none) resistance when sliding the lever between Auto and Manual.
  • Jellis
    Jellis Member Posts: 228
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    You mentioned how dark your water was when you bled the loop... You could bleed the other loop and flush out the boiler while your messing around with things.
  • hot_rod
    hot_rod Member Posts: 22,254
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    If you have any flow at all the air purger will clean up the final bubbles. make sure that float auto vent is working also.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • hot_rod
    hot_rod Member Posts: 22,254
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    When you manually open a zone valve like that you need to latch the lever or it will spring close again. IF the stem is broken it will feel loose across the range.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • cbodary
    cbodary Member Posts: 11
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    Sorry for disappearing. I had to walk away from the issue for a few days, and I was traveling. It's driving me crazy. Since my last post:

    I shut off the thermostat that controls the faulty zone. The lever on the back of the zone valve moved to Auto. I moved the lever back to Manual and there was definitely resistance. Question: If thermostat is calling for heat and I move the lever from manual to auto, should there be resistance that way? I left it "locked" in manual for several days. No change in the symptoms. I have hot copper out to the first register in the zone, but no heat afterwards. The copper above the zone valve is cool to the touch.

    I pulled the zone valve motor off the valve and looked at the gears... they look ok? With the motor off I turned the thermostat to "Heat" and the motor definitely tries turning. I say try, because it seemed odd to me. It made a clicking noise repeatedly as if it was trying to turn, but couldn't. I assume perhaps since there was no resistance it wasn't turning? I switched the thermostat off. I verified the ball valve shaft would turn left and right. I made sure the gears on the motor lined up with the shaft coming from the ball valve and replaced the motor.

    I used a voltage meter to verify that I was getting 24V AC at the zone valve, when the thermostat is calling for heat. I kind of knew that already, because I could see the switch on the valve move left/right as I turned the heat on/off. There are two sets of red/white wires connected to the top of the zone valve. The connections with wire coming from the thermostat read 24V. The other connections (wires connecting to the other zone valve) had no steady current reading. Normal?

    So what's next? Is it possible that despite the ball valve stem turning the valve isn't actually opening inside the copper? Could it not be opening far enough? Would it be worth the time/effort to switch the two zone valves to see if symptoms changed?

    Still scratching my head.
  • Grallert
    Grallert Member Posts: 656
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    If that power head was clicking when powered up to open the valve the gears are stripped and jumping. you can swap the power heads to prove this. My guess is that power head is bad. Now sometimes the stripped gears on the head are caused by a stuck or seized up valve that over strains the head. With the power head off you should be able to turn the stem of the valve with you fingers or with a little adjustable wrench and find little resistance. Repair kits are available for those valve bodies.
    Miss Hall's School service mechanic, greenhouse manager,teacher and dog walker
    SuperTechMikeL_2
  • cbodary
    cbodary Member Posts: 11
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    I just placed an order for a new Zone Valve head. I should have it Sunday. Fingers crossed.

    Dumb question: If I turn the zone valve stem manually (with my hand) it does turn with slight resistance, but which way do I turn to open the valve: left or right?
  • SuperTech
    SuperTech Member Posts: 2,186
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    > @cbodary said:
    > I just placed an order for a new Zone Valve head. I should have it Sunday. Fingers crossed.
    >
    > Dumb question: If I turn the zone valve stem manually (with my hand) it does turn with slight resistance, but which way do I turn to open the valve: left or right?

    Lock the zone valve in the open position and line the stem up with it when you install it.
  • cbodary
    cbodary Member Posts: 11
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    I'm starting to feel really dumb.

    I did as suggested. I received the new zone valve. I moved the lever to the manual/open position and locked in place. I lined up the stem (manual valve turns freely) and installed the valve. To ensure I reattached the wiring in the correct posts I snapped a photo prior to removing the suspect zone valve. I restored power to the boiler, and turned the thermostat to "heat". I walked away for 15-20 minutes.

    When I returned the zone valve was still open (as far as I could tell). The valve lever would move back-and-forth freely as the thermostat was still calling for heat. The valve motor was hot to the touch. The outgoing copper was very hot... return copper was cool. The copper in and out of the first register in the loop was hot. Fifteen feet further down the loop the copper going into register #2 was still not hot. It was only slightly warmer than the return copper above the zone valve.

    Again... zone 1 continues to operate normally.

    This certainly smells and feels like an air lock. Do I try a third time to purge air out of the loop? Is there anything else I can troubleshoot?
  • Grallert
    Grallert Member Posts: 656
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    So you now can verify that the valve is working? It opens and closes with the thermostat? I forget what you have calling the circulater. Can you verify that it is working? is the circulater working? If the circulater is running and the ZV is open then I would again start looking for air in the system.
    Miss Hall's School service mechanic, greenhouse manager,teacher and dog walker
  • rick in Alaska
    rick in Alaska Member Posts: 1,457
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    As Dan Holohan says, if you are bleeding and not getting air, it's not an air problem. And. if you power up that zone valve when it is not installed, it will make those clicking/gear stripping sounds. I doubt it was bad.
    Try this; hook up your drain hose again, but this time close the other ball valve. Not sure if it is the return or supply line, but the line that does not have the zone valve on it. Now, open up the zone valve manually, and the ball valve under it, and make sure you are getting flow out your drain valve. I have had the ball on those zone valves fall apart and block the flow. You might just have to replace the zone valve conversion kit under the powerhead to fix this problem.
    Rick
  • Jellis
    Jellis Member Posts: 228
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    I would say your zone valve is working by what you describe.

    reasons why water will not circulate through a loop

    1. circ pump not working
    2. restriction in line (frozen pipe, closed zone valve, failed check valve etc)

    Try closing the supply and return on the "good" zone during a call for heat on the "bad" zone. this may force water through the loop and get the air bubbles moving and vent some air out of your air scoop (assuming your air vent is open and working)

    If this does no get hot water moving through the zone then yes try purging again.
    when you purge keep in mind you need to keep enough pressure in the loop to keep it full of water ALL THE WAY TO THE TOP. If you purged the zone with the valves all the way open and just feeding water at 12-15 psi then i am sure you left a nice air pocket in the top of the loop.
    when purging the loop try to keep it around 20-25 psi to ensure enough pressure to fill the entire system.
  • cbodary
    cbodary Member Posts: 11
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    I completely agree... that's why this has been so frustrating. I'm going to try again this evening to purge. During my last attempt at purging I tried to keep the pressure between 20 and 30 psi. Do I dare let it go higher? Perhaps I just didn't purge long enough, or maybe I had the drain valve open too far.

    Is it possible the manual (ball) valve in the zone valve is bad and is blocking the flow regardless of what the electronic/motor portion of the valve is doing? The stem does turn left/right, but only God knows what's going on inside that copper.
  • rick in Alaska
    rick in Alaska Member Posts: 1,457
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    Look at my post above to check if your zone valve has a broken ball inside. It will give you an idea if it is broken or not, but open the drain slowly at first. If you open it too fast, and the ball is broke loose, it might slam it to the other side and seal it off.
    I still have a hard time believing it to be air after the purge you did.
    Rick
  • cbodary
    cbodary Member Posts: 11
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    Rick I'd love to try that, because I do get hot water out of the boiler. It seems I can't get water in the loop to come back into the boiler. I've always had hot water in the first ~ 30 feet in the loop (as far as I can reach beyond the copper fin register in my photos above). The next register in the loop is another ~ 15 feet away (into the next room)... no heat. To do the test you're suggesting I'd need a ball valve below my drain, but I only have a ball valve above the drain. :-(

    Yesterday / last night: I closed both ball valves on the working zone, and kept the faulty zone open with a call for heat... hoping it would isolate the circulation of hot water. This had no affect. I also carefully purged the faulty zone as instructed by Jellis and Super Tech. I kept pressure above 20 psi.. and as high as 40 psi. I did get a few pockets of air, but still no progress.

    I appreciate everyone's assistance with this, but I'm starting to think I'm going to have to throw in the towel and call in an expert.
  • Grallert
    Grallert Member Posts: 656
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    A few pockets of air. That tells me it's likely still got an air bubble and that will stop the flow once,. The pump will not be able to move water past it. Do you get hot water out of the purge station while you purging air?
    Miss Hall's School service mechanic, greenhouse manager,teacher and dog walker
  • cbodary
    cbodary Member Posts: 11
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    Yes Grallert. When I purged last night the water started out cool, then got hot (I assume this was the water from the beginning/front of the loop), and then got cold (water being pushed in from the water feed valve?).

    I can understand the skepticism about the issue being related to an air bubble, because I've purged a LOT since the issue started.... but I don't know of anything else that could be causing this. The circulator would be the other target, but my other heat zone (which goes upstairs) is fine.
  • Grallert
    Grallert Member Posts: 656
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    It is possible that your upper levels are being heated by gravity. Though I'd think you would notice the slow response if that were the case.
    Miss Hall's School service mechanic, greenhouse manager,teacher and dog walker
  • rick in Alaska
    rick in Alaska Member Posts: 1,457
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    What I am saying is this. Leave your hose where it is. close the ball valve on the other manifold. Open the ball valve under the drain line, and open the zone valve manually. You should get a lot of water coming out this way. If you don't, there is a restriction somewhere in the piping below your purge valve. Most likely in the zone valve.
    On your last post you mentioned the upstairs zone works, but not the downstairs. Makes me also wonder if it is a pumping problem. Top floor will get some gravity feed. What is the system pressure, and are you sure the pump is working?
    Rick
  • cbodary
    cbodary Member Posts: 11
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    Ok so you're suggesting I do this... I'll try anything at this point.

    Do I need to use the fill valve to maintain 12-15 psi, or higher, for this test?

    As far as the circulator goes... I assume it's working, but that's solely based upon the fact that I do have heat in the upstairs zone.
  • Jellis
    Jellis Member Posts: 228
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    A Amp test on the circ pump may be a good idea too.
    Clamp on Ammeter on a pump lead and verify it against the running amps on the label.

    Perhaps your swing check is sticking?



  • rick in Alaska
    rick in Alaska Member Posts: 1,457
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    cbodary said:



    Ok so you're suggesting I do this... I'll try anything at this point.

    Do I need to use the fill valve to maintain 12-15 psi, or higher, for this test?

    As far as the circulator goes... I assume it's working, but that's solely based upon the fact that I do have heat in the upstairs zone.

    Yes. Do it the way you have shown, and keep the pressure up.
    Rick
  • HomerJSmith
    HomerJSmith Member Posts: 2,467
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    I'm going out on limb here. So I'll make some assumptions.

    The zone that works is the shortest zone and the zone the doesn't work is the longest zone. What I am thinking is that the shortest zone has the least pressure loss and the longest zone has the greatest pressure resistance. I think that you may not have air in the line at all.

    If the zone valve is open and you don't have flow, it may be because the cartridge in the pump is fouled and not rotating sufficiently to move water thru the circuit which would mean you would need a new cartridge for the pump. Sometimes the cartridge costs about as much as a new pump. If that's what you need to do, you might consider a Grundfos equivalent.
    Jellis