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  1. #1
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    Over sized liquid line filter?



    Hi. Please excuse my noob question.

    I'm reassembling a cooler and I'm having a hard time sourcing a liquid line filter that matches the tonnage of the unit and copper tubing size.

    What do people do in this case?

    1) Use a larger filter that is specified to be used in a larger tonnage unit.
    2) Use the right size filter that has smaller copper tubing size. (1/4" instead of 3/8")
    3) Mail order the right one and wait.

    If scenario 1 is used, how do you figure the extra refrigerant you need in a critical charge (capillary tube) system? Would the extra refrigerant affect system performance?

    If scenario 2 is used, would this restrict the flow of refrigerant and cause problems?

    Thank you!



  2. #2
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    Re: Over sized liquid line filter?

    Pick number 1. Never have known it to be trouble to use a larger filter drier.

  3. #3
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    Re: Over sized liquid line filter?

    .

    Don't get hung up on the size or tonnage of the dryer.

    You need to understand what they are!

    Filter dryers are installed to catch moisture we leave in the system after we repair
    or install them. The dryer normally would not be required if we could garentee the
    system was install or repaired correctly.

    The dryer also filters out any solids we leave inside, like copper filings or dust particals.

    The dryer needs to be of the correct pipe fittings but after that most will fit any aplication.

    Make sure it is rated for the refrigerant you use. You do not want a pressure drop over the thing
    so going larger would make more sense compared to going smaller. Do not drop the pipe in diamter.

    When you look at brand new factory built systems the dryer is tiny in comparason to the ones we
    use to replace them with and that is because new factory built systems are as pure as pure
    can be with no contaminates inside.

    We need to carry out the repairs to the same standards...

    All the best

    coolrunnings

    .

  4. #4
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    Re: Over sized liquid line filter?

    The Sporlan driers have a chart with their refrigerant volumes, you can use this to work out how much more the system might need.
    Mostly found in Oxfordshire, UK :)

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    Re: Over sized liquid line filter?

    Ok, I thought that might be what it meant. It's a 10oz r134a system, the filter says 6.9oz, that just seemed like a lot.

    When installing liquid line filters, does the orientation matter (i.e. horizontal or vertical, I know the flow only goes one way)? For example, should I install it with the outlet pointing down so that oil doesn't collect, etc? Would that just create another problem by making a p-trap out of copper piping that was horizontal before?

    Thanks everyone!

  6. #6
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    Re: Over sized liquid line filter?

    If its a small cap tube system i probably wouldn't go bigger than a 032 drier, but i can't see the system from here.
    If you have the time and can get one then the best thing would be to fit one like it had originally in the same orientation, that way the system should work as the designers intended.

    The outlet generally wants to be lowest as cap tube systems don't run with a full liquid line and it could make a trap otherwise.
    Mostly found in Oxfordshire, UK :)

  7. #7
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    Re: Over sized liquid line filter?

    Yeah, I'd need a 033 (3/8") one to not go smaller in tube size. I can't seem to find one local, but they have lots of 032 and 083. The system is 1/3 ton, and according to sporlan's charts I need a 053-s. The filter is horizontal currently, but the original filter is a spun copper and it's small. I thought manufacturers could go with small filters because they have better ability to ensure dryness, cleanliness, etc.

  8. #8
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    Re: Over sized liquid line filter?

    In your other post, you said you were pulling apart a dead cooler to see how it worked, so now you want to put it back together right? Do you know if the compressor is o.k? It's just that i can see problems developing as now there is a contaminated evaporator to clean out and discoloured oil to deal with. If you are licenced to handle and dispose refrigerants, then so be it as it is your money. A 10 onz system with 3/8 liquid line seems overkill to me, most capillary systems of that size here are 1/4 inch, so i'd go with o32 flare or solder AFTER cleaning out system. Refrigeration supplies in your area can help with flushing solution but precautions must be taken when using chemicals and ofn (dry nitrogen) under pressure.. Mike.
    To the optimist, the glass is half full. To the pessimist, the glass is half empty.

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    Re: Over sized liquid line filter?

    Yeah, seems that everything about this cooler is overkill. It has the thickest insulation I have ever seen in a worktop cooler. I imagine it was very pricey when new. To be honest, aside from some waxy slime substance that I mistook for POE oil on the end of the evaporator, the whole system looks almost new.

    I'm pretty sure the compressor is ok. It ran before I took apart the system.

    Yep, I'm licensed (US EPA and Texas). So far I'm into this 50$ for the cooler, ~12$ for a filter, 10$ for copper fittings, then flushing compound, new valve cores and refrigerant. And of course my time, which I'm having a mostly good time learning. I already have my recovery system, brazing kit, n2, recovery tanks, etc.

    Thanks for your help!

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    Re: Over sized liquid line filter?

    Copeland manuals suggest that larger filter driers on critical charge systems can cause compressor failures by accumulative flooded start wash and wear of the compressors lubricated moving parts. The implied extra charge, which then waits in the evaporator before every next on-cycle, floods back each on-cycle - or at least increases the volume of liquid flood back.
    Only the dogmatist says he will never change his mind. We all know that some of our opinions are wrong but none of us know which they are for if we did then they just wouldn't be our opinions. - JS Mill.

  11. #11
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    Re: Over sized liquid line filter?

    Would a suction line accumulator relieve this problem? Or does any liquid reaching the compressor cause problems?

    I finally found a place with the right size filter this morning, so I'm just curious at this point.

    Thanks!

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    Re: Over sized liquid line filter?

    Quote Originally Posted by DTLarca View Post
    Copeland manuals suggest that larger filter driers on critical charge systems can cause compressor failures by accumulative flooded start wash and wear of the compressors lubricated moving parts. The implied extra charge, which then waits in the evaporator before every next on-cycle, floods back each on-cycle - or at least increases the volume of liquid flood back.

    Live and learn! Makes sense on really small stuff.
    Mostly found in Oxfordshire, UK :)

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    Re: Over sized liquid line filter?

    Quote Originally Posted by clearchris View Post
    Would a suction line accumulator relieve this problem? Or does any liquid reaching the compressor cause problems?

    I finally found a place with the right size filter this morning, so I'm just curious at this point.

    Thanks!
    Well, I would have thought that as long as you still charge the system with the name plate weight, even with the new oversized drier, and that new drier was installed vertically with flow into the expansion device downward, then maybe feed to the capillary will resume as design intentions had it. The main concern of course is simply about the tendency to increase the refrigerant charge when oversizing the drier volume.
    Only the dogmatist says he will never change his mind. We all know that some of our opinions are wrong but none of us know which they are for if we did then they just wouldn't be our opinions. - JS Mill.

  14. #14
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    Re: Over sized liquid line filter?

    Quote Originally Posted by clearchris View Post
    Would a suction line accumulator relieve this problem? Or does any liquid reaching the compressor cause problems?

    I finally found a place with the right size filter this morning, so I'm just curious at this point.

    Thanks!
    The sound of fish and chips cooking inside the compressor is never a good sign, tells you liquid is knocking at the door. you can add accumulator but design should already have one at outlet of evap.
    To the optimist, the glass is half full. To the pessimist, the glass is half empty.

  15. #15
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    Re: Over sized liquid line filter?

    Mikeref: Yes, it already has an accumulator. I should have said a "full size accumulator", relative to the new (hypothetical) charge.

    Yikes, fish and chips from the compressor. That doesn't sound tasty at all.

    DTLarka: Yeah, that was my thought about eliminating any trap by installing it outlet down. But that idea only works if one assumes the filter fills with vapor and the liquid flows through and doesn't collect. I don't know enough to know if that's a good assumption or not.

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    Re: Over sized liquid line filter?

    Haven't had that happen in critical charge systems yet? If system is overcharged, then not long after compressor start, when cabinet is within temperature range, (zero to say, +4 C), liquid floods back and boils in the warm compressor oil which makes the sound of a frozen potato chip going into deep fryer, then you are seriously close to loosing your compressor. BTW, What area of refrigeration do you work in?..Mike.
    To the optimist, the glass is half full. To the pessimist, the glass is half empty.

  17. #17
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    Re: Over sized liquid line filter?

    Nope, not yet. I think I err on the side of undercharging systems, but I'm learning. If I should get some time, I'd like to build a charging computer. In my prior career I was a programmer, and lately have done some work with arduino boards.

    I mostly deal with small commercial appliances. I'm certified to work with all equipment though.

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