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  1. #1
    Join Date
    Jul 2009
    Location
    Independence
    Posts
    197

    Unhappy Reach-In Freezer Fan

    Say we have a small reach in freezer.
    ive evacuated it, vacuumed, and weighed in the charge.
    and cleaned the condenser thoroughly. so i know that much is done.
    yet i still seem to have problems getting the case temp much lower
    than 27* at best. One thing that seems strange is that the air from the
    E fan doesnt seem to be blowing very hard. This Hobart QF2 has only
    One E Fan and discharges through a column in the back center of the
    case. Is it likely the fan is not turning fast enough? Or i wonder if somebody in the past has replaced it with the wrong motor. Is there anyway to verify the fan speed short of an IR Tach gun?

    ??

  2. #2
    Join Date
    Mar 2006
    Posts
    1,042
    stick a zip tie in the fan and count very fast

    other then that i wouldn't know of another way.. maybe easier to just get the motor its supposed to have and go from there

  3. #3
    Join Date
    Jan 2008
    Location
    michigan
    Posts
    1,145
    Quote Originally Posted by marter View Post
    stick a zip tie in the fan and count very fast
    LMAO. Agree wtih the rest of your response as well. Just verify if motor is correct via manufacturer,

  4. #4
    Join Date
    Sep 2002
    Posts
    13,551

    Is the blade correct ?

    In the fan blade the correct rotation for the motor?

    Is this a little open-frame fan motor?

    PHM
    ---------



    -------pitched for theCould
    Quote Originally Posted by VAV616 View Post
    Say we have a small reach in freezer.
    ive evacuated it, vacuumed, and weighed in the charge.
    and cleaned the condenser thoroughly. so i know that much is done.
    yet i still seem to have problems getting the case temp much lower
    than 27* at best. One thing that seems strange is that the air from the
    E fan doesnt seem to be blowing very hard. This Hobart QF2 has only
    One E Fan and discharges through a column in the back center of the
    case. Is it likely the fan is not turning fast enough? Or i wonder if somebody in the past has replaced it with the wrong motor. Is there anyway to verify the fan speed short of an IR Tach gun?

    ??
    PHM
    --------
    The conventional view serves to protect us from the painful job of thinking.

  5. #5
    Join Date
    Jul 2009
    Location
    Independence
    Posts
    197

    Smile

    Quote Originally Posted by marter View Post
    stick a zip tie in the fan and count very fast
    HaHa,

    Now, i have weighed the charge in , filling my gauge hoses first , then zeroing the scale to be sure im not counting the 3 or 4 oz in the hoses. so im sure the charge should be about right. and i get
    20# AKA 404a @ -16*
    240#
    with the case temp at 40* im not surprised to see the SH at 60+*(cap tube)
    but what bothers me is with a return of 40* my supply is only 35* at best.
    shouldnt i see more like 10* across the coil? and the normal operating temp of the evap should be -15*, yet would it already be that low when the case is far from its proper temp? i thought i might expect to see it higher than that untill the case gets a bit colder.

    im pretty convinced now that ill just change the fan and see what difference it makes. But IDK how hard it will be to get the specs outa HOHOHObart

    TY

    VAV

  6. #6
    Join Date
    Jul 2009
    Location
    Independence
    Posts
    197
    i havent taken a good look at the fan yet, is there a tendency of
    open frame motors to slowly open up and slow down, or something?
    I am sure that it turns the right way though, as the return goes in the
    top of the case, and the supply comes out the center column down the
    back of the box. but i have no way to verify what the proper blade pitch should be.
    ty

    VAV

  7. #7
    Join Date
    Sep 2002
    Posts
    13,551

    I don't mean the pitch

    But rather the way the blade is suppose to turn. Is the blade turning so as to 'cup' or 'scoop' the air? If the blade or motor was replaced and do not match in rotation then the air flow will be much reduced.

    That was my point.

    PHM
    ---------


    Quote Originally Posted by VAV616 View Post
    i haven't taken a good look at the fan yet, is there a tendency of open frame motors to slowly open up and slow down, or something?
    I am sure that it turns the right way though, as the return goes in the
    top of the case, and the supply comes out the center column down the
    back of the box. but i have no way to verify what the proper blade pitch should be.
    ty

    VAV
    PHM
    --------
    The conventional view serves to protect us from the painful job of thinking.

  8. #8
    Join Date
    Dec 2007
    Location
    Lancaster, PA
    Posts
    16
    If the fan were spinning slower than it was designed to wouldn't that give you a greater air TD across the coil? If your evap fan is slow that would also give you a low heat load. With a low heat load your SH shouldn't be at 60* after running for a short while. Are you sure your evap is feeding properly? Is it a single capillary circuited evaporaor, or multiple? What does the frost formation look like on the coil? And how long did you let it run?

    I have bought a new laser tachometer off of ebay for about $20 delivered a couple years ago and it works fine. I think the brand was nekko or neico or somethin like that. I wonder if it was made in china????LOL

  9. #9
    Join Date
    Feb 2006
    Location
    Phoenix,AZ
    Posts
    2,895
    Whats your SC? Sounds like you maybe stacking refrigerant in the condensor and need to change the partialy restricted cap tube.

  10. #10
    Join Date
    Apr 2009
    Location
    Oxnard,CA
    Posts
    2
    we take care of one QF2 and two QF3's. They all have 9 watt motor, 1550rpm, 115v, cw.

  11. #11
    Join Date
    Jul 2009
    Location
    Independence
    Posts
    197

    Hmm

    Yes, it is a dual cap tube system. and i have not measured the SC.
    /baddog
    trying to solder captubes doesnot sound like fun.
    I do now realize that less airflow would indeed make a Greater delta T.
    So, i guess restriction makes more sense but, i thought with a cap tube restriction i might see an iceball forming at the point where the restriction is.

    The coil forms ice begining from the side where the cap tube enters, and the build up starts in the middle of the coil on that side. It does seem to freeze up too soon. i have the clock set to four times a day for about 20 min, and actually i think it doesnt take quite that long to defrost. but i havent been able to sit and watch the unit to see exaclty how it behaves.
    Ill go back today and measure the SC.

    ty

    VAV

  12. #12
    Join Date
    Jul 2009
    Location
    Independence
    Posts
    197

    TEV or Captube

    Ive heard some suggest replacing captubes with a TEV on this type of unit.
    What do you guys think of that?
    The average person has one testicle, and one ovary.

  13. #13
    Join Date
    Sep 2005
    Location
    florida
    Posts
    5,514
    Quote Originally Posted by VAV616 View Post
    Ive heard some suggest replacing captubes with a TEV on this type of unit.
    What do you guys think of that?
    You would need a reciver to do that.
    I love the smell of phosgene first thing in the morning:

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