QF Castile: No Vacuum - Going Crazy Trying to Figure It Out

xcookpac Posted By xcookpac, Mar 4, 2018 at 1:37 PM

  1. xcookpac

    xcookpac
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    Hi there, my name is Pete. I am a brand new member (although I have been lurking for quite some time). I have been trying to analyze my vacuum problem (namely, I am registering no vacuum at the nipple adjacent to the auger chamber).

    Background: I purchased my QF Castile insert second hand about three years ago. It was working great until a few months ago when the pellet stove stopped feeding pellets. After cleaning the entire stove thoroughly to no avail. I tried jumping the vacuum switch and immediately the pellet stove cam back to life. Pellets feed properly and auger functions properly so long as I jump the vacuum switch. In an attempt to determine the problem I took the following steps:

    1.) I attached a vacuum gauge to nipple adjacent to the auger chamber (where the vacuum hose is normally attached for vacuum switch) and found that I have nil ("0") vacuum at the nipple;

    2.) I checked the fire-pot ash door and determined that the ash door was completely closed;

    3.) I removed and cleaned the pipe from the pellet stove to the woodstove liner and adapter (I attach the 4" pellet stove piping to the woodstove liner/adapter) which then goes up my chimney. I little bit of ash but not too bad.

    4.) Chimney damper is confirmed open;

    5.) I checked the door seal on the pellet stove and found that only three ("3") sides of the door have a seal (no seal on top of the door). After reading up on this issue it appears that this lack of seal is not a problem as it appears that QF did not include this seal in order to provide an "air wash."

    6.) I removed the exhaust combustion blower and vacuumed the inside of the passage way (where there was little ash and grit). And, I cleaned all the residue off the combustion blower fins and then reinstalled the blower while utilizing GM RTV Engine Sealant as the gasket (on top of the fiber gasket.

    7.) I hooked my vacuum pump (which I usually use for AC evacuation) to the nipple adjacent to the auger chamber. And, I found that the pump (which normally develops one atmosphere or 29"hg) was creating 5"hg of vacuum. Once pump shut off then the vacuum immediately dropped to nil ("0").

    8.) I paid particular attention to exhaust combustion blower after reinstalling it (described above). So that when I restarted the pellet stove (with vacuum switch still jumped), I noticed that this blower started very slowly (is it possible for this blower to be running below optimal speed despite being on high).

    Questions for the Hearth Experts:

    a.) What should I check next?

    b.) What rpm should the exhaust combustion blower run at?

    c.) Is it possible that the exhaust combustion blower is running too slowly?

    d.) Does anyone have a better way of finding pellet stove vacuum leaks?

    Any help that could be provided would be greatly appreciated. I am racking my brain on this problem (I have fixed a lot of vacuum leaks on cars over the years but this one has me stumped).
     
  2. bob bare

    bob bare
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    If you used an automotive vacuum gauge,you will not see a reading,you need a magnahelic gauge.You may only have a bad vac switch.You also could make a jumper,and wire it to combustion blower(unwire from stove),plug into wall outlet and see how the motor starts/runs.
     
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  3. johneh

    johneh
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    Vac will not show on a vac gauge amount of vac pulled is way to small
    if you jumped the switch and stove ran and the hose and nipple are OK
    replace switch Welcome to the forum
     
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  4. Overfireinthehole

    Overfireinthehole
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    Did you blow through the vacuum line? Is the vacuum switch metal or plastic? How did you clean the flu? Sometimes a piece of pellet or dust can clog a line. If you have an old metal switch it might be bad but take it off and knock any dust out of it to be sure. If you haven’t run a brush up your pipe you might still have a clog. If it’s just a bad vacuum switch or clog in the hose then your stove will burn fine with the switch jumped but if it’s a bad gasket or clog in exhaust system then you’ll usually get a lot of black soot in your firebox area and it may take longer to light.
     
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  5. xcookpac

    xcookpac
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    Thanks for the replies so far. I looked up "magnahelic gauge" on Toptooltips. See http://toptooltips.com/magnehelic-gauges-review-definition-calibration-of-differential-pressure-gauges/ And, I got the following: description and pic:


    "In industries like HVAC where monitoring the air pressure difference between two locations is of vital importance, the need for a reliable and accurate means to measure differential pressure is needed. There are several ways you can measure pressure but the simplest, and probably the best, way to measure this value is through the use of a magnehelic gauge.

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    What is a Magnehelic Gauge?

    The simplest magnahelic gauge definition is that it’s an instrument used to measure pressure. It is mainly used in measuring positive or negative pressure (also known as vacuum); it also used to get the difference in pressures between two separate locations."
     
  6. xcookpac

    xcookpac
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    Apparently, based on the internet write-up at toptooltips (referenced above in my prior post), the magnehelic gauge measures the pressure differential at two different points.

    Q1. Please confirm that we are measuring the difference in pressure between the atmosphere (approx 30"hg) and the pressure (or vacuum) at the nipple (adjacent to the auger box).

    If that is correct, what is the specification for such differential?

    Q2. Does QF provide this specification for vacuum at the nipple?

    Q3. Is there a specification for what vacuum should cause the vacuum switch should to close?

    Once again, your assistance is greatly appreciated.

    PS I sucked on the vacuum hose for the vacuum switch (while it was disconnected and outside the pellet stove). I checked for continuity between leads upon application of vacuum and I got nil resistance, perfect continuity, once I applied the vacuum.

    PPS My vacuum switch is a shiny, steel, round vacuum switch.
     
  7. bob bare

    bob bare
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    Used on a pellet stove,one point is the stove(vacuum),the other point is atmospheric pressure,just open to the room.Most stoves draw only .8 inches of water or less.Which is way less than an automotive vacuum gauge.You can make a simple gauge with a section of clear tubing,can be found on net.
     
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  8. Overfireinthehole

    Overfireinthehole
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    That switch should be labeled but it should close at -.05”. Anything further to the left or more into the positive will prevent closure. This vacuum reading should be taken at the end of the hose where it connects to the switch. If your getting continuity through your vs then that’s not the problem ( unless the switch has a weak connection that fails after warming up), but you said it feeds when you jump the switch? I’d replace that old vs with one of the new plastic ones. When they get old they tend to get a lot of carbon buildup on the contacts inside the switch which can give you intermittent or less than optimal continuity.
    https://pellet-stove-parts-4less.com/ has your switch cheap.
     
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  9. Overfireinthehole

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    Q1, I’m not 100% sure but I believe your measuring the difference between atmospheric and inside the stove. Your getting in over my head about how The gauge actually works. I do know most manometers have a positive and negative port, so make sure your checking for negative pressure.
     
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  10. bob bare

    bob bare
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    Yes,good explanation.
     
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  11. corkman

    corkman
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    You tested for vac at the nipple and results were no vac. So clear that nipple with a paper clip or disconnect the tube from the vacuum switch and blow into the tube to clear it
     
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  12. bob bare

    bob bare
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    It appears he checked it with an automotive vac gauge,read the whole thread.
     
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  13. xcookpac

    xcookpac
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    Thanks for all your very helpful input and feedback. Next weekend, I will attempt to build a u-tube water filled manometer in order to measure:

    a.) the pressure differential between atmosphere and nipple adjacent to the auger box; and

    b.) amount of vacuum required to cause my existing switch to close (and thereby provide continuity between the terminals).

    I will check back in with all of you when I have built the u-tube manometer with my results.

    Thanks again.
     
  14. peirhead

    peirhead
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    I had a similar problem with my Castile, turned out to be pellet fines (very fine fines) getting back into the actual vac switch through the tube. I removed the switch and tapped it on a table until it stopped disgorging wood dust.. It took a while and I was amazed how much had accumulated in the switch. then I cleaned out the hose and reassembled...worked great ever since!!
     
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  15. xcookpac

    xcookpac
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    Decided to purchase a cheap manometer from Amazon (instead of building a water manometer). Manometer just arrived and I did the following:

    1. Plugged in stove without lighting it but with exhaust fan blowing;

    2. Manometer measured 0.11 to 0.12 H2O inches of vacuum differential between the nipple and the atmosphere.

    It seems to me that my vacuum reading is within range. And, now it is time to test the vacuum gauge (I will do that shortly and get back to all of you on that).

    Q1(a): Finally, should the manometer reading change once the fire is fully lit with pellets feeding?

    Q1(b): If so, how much should the reading change?

    Many thanks again for all of you helping me get to the bottom of these issues.
     
  16. xcookpac

    xcookpac
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    I am going to check the vacuum gauge for accumulation of fines as mentioned in peirhead's posting above.
     
  17. johneh

    johneh
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    The vac you are reading is well with in the specs for your stove
    So if you jump the vac switch and the stove runs normal
    REPLACE THE SWITCH . This is not rocket science
     
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  18. xcookpac

    xcookpac
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    I turned the vacuum switch over and rapped it gently on the kitchen island and about 1/ 4 teaspoon of fines came out. I then tested the vacuum switch and it closed at approximately 0.1"H2O vacuum. I then reinstalled the vacuum switch into the pellet stove and now the pellet stove is working nicely (although I have a new issue regarding flame height not staying at the same height - but that is a new issue apparently unrelated to my vacuum switch - no feed issue).

    New Issue: s it advisable to place a fuel filter (from a small engine) with a 1/4" inlet and outlet between the nipple and vacuum switch? It seems the fuel filter would allow vacuum to pass but prevent fines from being sucked into the vacuum switch. Has anyone tried this solution and are there any down sides?

    Thanks again everyone on this board for their assistance in getting these issues resolved.
     
  19. johneh

    johneh
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    May be I am ass backwards but is the vac not being pulled from the switch ?
    How did the fines get into the switch ?
    In 16 years I have never had fines in my switch
    What am I missing about your stove ?
    I would not put a filter in the line may cause to much resistance
    to get a proper vac reading Also just something else to go wrong
     
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  20. xcookpac

    xcookpac
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    My theory on the ash getting into the vacuum switch is that the vacuum in the vacuum line causes some ash particles to get sucked into the vacuum switch. However, I do not have a cause and effect proof of what causes this condition. Pierhead alerted me to this issue (of fines on the vacuum switch). And, lo and behold, I also had fines in the vacuum switch. Once, I cleared the fines, the vacuum switch worked fine.

     
  21. Overfireinthehole

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    I see it all the time. Doesn’t make much sense but it happens.
     
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  22. bob bare

    bob bare
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    I agree with Over,it does happen.Seems to happen more with people that run the stove dry(run it out of pellets).A inline filter is an excellent idea,if you own a stove that has done this.Also,in my experience,most stoves will go to .4 to .6 when starting/no flame,then drop back to .15 to .3 running.Depending on your altitude,.1 may be fine,I prefer to see it slightly higher.
     
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  23. xcookpac

    xcookpac
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    Thanks Bob, I tested my stove with the manometer when the stove was starting without flame. Which apparently means that my reading (namely, vacuum in the 0.11"H20 to 0.12"H20) is a little high. Is there something that should be adjusted (or do we wait until retest with normal burn)?

    I will retest with manometer this weekend with the stove fully running with pellets (I may have to manually disconnect the auger in order to avoid the overfill condition).

     
  24. hearthtools

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    The one I use I got from Amazon about $35 2594f8ee03692a805c861e35460b64f4.jpg

    Sent from my HTC6545LVW using Tapatalk
     
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