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  1. #40
    Join Date
    Jul 2012
    Location
    Western KY
    Posts
    1,221
    You've got alot of good info on this thread now go kill it and drag it home.

  2. #41
    Join Date
    Aug 2012
    Posts
    18
    [QUOTE=Tommy knocker;13917851]You've got alot of good info on this thread now go kill it and drag it home.[/QUOTE


    I did just that! Sorry for the delay in an update but the last week has been busy. The 100 degree + Month of July sure weeded out the weak ones.

    My walk-in is up and running and has been for a week. I am notb entirely sure I have a complete full charge yet that will operate system @ -20 ambient. but it is working well in the 65-100 degree ambient we have been experiencing the last 10 days. I still do have a couple of questions though.

    On determining a full charge to (-20) ambient this is the way I figured it based on the the Sporlan bulletin 90-30-1.
    Condeser is 3/8" tubing, 28" long with a total of 42 tubes and 42 return bends.

    42x28=1176/12=98lf of tubing 42x.200=8.4lf for the return elbows Total tubing =107lf

    107x .050= 5.4 lbs additional refrigerant after inital fill to clear sight glass.

    My initial charge was 6lbs 4 oz to clear sight glass. I added and additional 4 lbs beyond that. In my mind 5.4 lbs additional seemed like alot for the small system that this is. That would put the total charge at aprox 12lbs. Right now it has 10.5 lbs. I understand the problem may come as Winter gets here and the ambient drops. Did I figure the additional charge properly?

    Is there a way to tell if a system is indeed charged for all ambient temps without dumping the charge and starting from scratch?

    Next, Sub cool as I measure it is somewhere between 6 and 9 degrees. From what I read suction temp and pressure should be measured at the TXV bulb. Temp is not a problem but this system has no service valve at the evaporator. Service valve on suction line is located on condenser which is just outside the cooler with about 8' of insulated line in between.How accurate is my subcool temp? Seems to me you might have a slight rise in suction temp/pressure between the evap and the service valve.

    Thanks again to all who have helped. I found out this week that I might just have a little more knowledge about this system than my boss who had this job before me. Great guy but when I began to explain the charging procedure to him I could see the lights go out and he just said "do whatever you think is right"!!!

  3. #42
    Join Date
    Oct 2011
    Location
    Chicagoland Area
    Posts
    4,627
    Quote Originally Posted by tomnkc View Post
    Is there a way to tell if a system is indeed charged for all ambient temps without dumping the charge and starting from scratch?
    No. Lineset probably being the biggest variable. With extended lineset runs adding a winter charge and subtracting a summer charge may be necessary unless you add an additional receiver. Refrigeration Research can give you an idea about how much refrigerant the receiver holds. Is -20 a probability in your neck of the woods?
    Officially, Down for the count

    YOU HAVE TO GET OFF YOUR ASS TO GET ON YOUR FEET

    I know enough to know, I don't know enough
    Liberalism-Ideas so good they mandate them

  4. #43
    Join Date
    Feb 2008
    Location
    California
    Posts
    2,066
    Quote Originally Posted by tomnkc View Post
    when I began to explain the charging procedure to him I could see the lights go out and he just said "do whatever you think is right"!!!
    that's good!

  5. #44
    Join Date
    Sep 2008
    Location
    Western PA
    Posts
    25,682
    You misseded a step.....

    Once you arrived at the 5.4# figure, you need to take that number to Table 2.

    So, assuming (bad idea, I know) a -25F evaporator and a -20F minimum ambient, you need 88% of that 5.4# figure or 4.752#.

    Since you've already put 4# in past a clear glass, add 12 ounces and call it DONE!

  6. #45
    Join Date
    Aug 2012
    Posts
    18
    Quote Originally Posted by 2sac View Post
    No. Lineset probably being the biggest variable. With extended lineset runs adding a winter charge and subtracting a summer charge may be necessary unless you add an additional receiver. Refrigeration Research can give you an idea about how much refrigerant the receiver holds. Is -20 a probability in your neck of the woods?
    -20 would be at the bottom of the of the scale for here in the KC area. But cosidering windchill it is a possibility. Also I misspoke/miswrote in my last post. Meant to say I have 6-9degrees of superheat not subcooling. Sorry about that. Still not sure if the temps are accurate based on what I posted before

  7. #46
    Join Date
    Sep 2008
    Location
    Western PA
    Posts
    25,682
    Quote Originally Posted by tomnkc View Post
    -20 would be at the bottom of the of the scale for here in the KC area. But cosidering windchill it is a possibility. Also I misspoke/miswrote in my last post. Meant to say I have 6-9degrees of superheat not subcooling. Sorry about that. Still not sure if the temps are accurate based on what I posted before
    Windchill doesn't affect refrigeration equipment.

  8. #47
    Join Date
    Feb 2009
    Location
    Wisconsin
    Posts
    311
    Good to see you got it and I would leave that charge right where it is for K,C.
    You have to fight through some bad days to earn the best days of your life.

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