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  1. #1
    Join Date
    Nov 2008
    Location
    Northern California, foothills.
    Posts
    212

    Use of suction line filter-driers?

    It is 2013. Sometimes you read about practices from the past and
    people mindlessly keep doing what they learned 20 years prior.
    I don't want to be such a victim.

    After a residential-sized compressor burnout, do people
    still ALWAYS install suction-line filter-driers?

    Do the acid neutralizer products and modern liquid line filter-drier-"Kleaners"
    somehow eliminate that need?

    In the past, our shop has been reluctant to install the suction line filters
    because of perceived customer objection to the additional cost of removing
    the thing a week later. I just want to get a feel for common SUCCESSFUL
    practice. Thank you.

    Edit: I'm admittedly posting this because I think that installing a suction
    line filter aimed at acid cleanup might have saved some repeated visits
    recently.
    Last edited by georgelass; 02-14-2013 at 11:41 PM.

  2. #2
    Join Date
    Oct 2012
    Location
    Sacramento,ca
    Posts
    196
    After a burn I nitro purge only, install new suction and liquid drier, change both after a few weeks, problem solved. More work, sure, but i think its worth it to not get a call back a year or two later for another bad compressor. I feel the people that are not doing this are setting themselves up to get a nasty call from a customer later

    Save yourself some headaches and include the future call to remove filters in your original quote so you are not billing them twice. That always upsets customers. I just explain this is the right way to do it, give them an all inclusive price and i have never had anyone fight me on it.

  3. #3
    Join Date
    Feb 2013
    Location
    north georiga
    Posts
    597
    i won't replace a compressor with out installing a suction dryer. i also try to get customer to let me spend the extra time to flush the coils, because of plugged cap tubes haunting me in the past. it's a pain but worth it

  4. #4
    Join Date
    Feb 2012
    Location
    Moscow
    Posts
    16
    I think the use of suction driers depends on numerous things. If there is a severe comp burn out, rather yes. If in the case of compressor mechanical problem rather no.

  5. #5
    Join Date
    Jun 2004
    Location
    Eugene, Oregon
    Posts
    1,018
    As a matter of best practices I would say that a suction drier should be installed and then removed after the system test clean. But I also think that if you do a acid test before the change out and the system test clean, you could probably get away with nitrogen purge, filter drier, new refrigerant, and a blessing from the dali lama.
    "The bitterness of poor quality remains long after the sweetness of low price is forgotten". --Benjamin Franklin
    "Don't argue with an idiot, they will drag you down to their level and beat you with experience". --Mark Twain
    http://www.campbellmechanical.com

  6. #6
    Join Date
    Apr 2012
    Location
    winnipeg
    Posts
    1,330
    Quote Originally Posted by air1 View Post
    As a matter of best practices I would say that a suction drier should be installed and then removed after the system test clean. But I also think that if you do a acid test before the change out and the system test clean, you could probably get away with nitrogen purge, filter drier, new refrigerant, and a blessing from the dali lama.
    i concure...
    it was working.... played with it.... now its broke.... whats the going hourly rate for HVAC repair

  7. #7
    Join Date
    Jun 2002
    Location
    Dacula, GA
    Posts
    12,612
    I wouldn't wait a week or more before checking out the pressure drop across the strainer. It may be plugged up by then.

    You should check the drop within a couple cays or so and the if it has a drop of 3 or 4 psi above the drop when clean replace it and install another one until you get 2 psi or less increase in your drop after a week or so and then you should remove it and your good to go.

    Waited to long to check one once and it had an excessive drop which cause compressor failure. Thank you very much
    "I could have ended the war in a month. I could have made North Vietnam look like a mud puddle."
    "I have little interest in streamlining government or in making it more efficient, for I mean to reduce its size. I do not undertake to promote welfare, for I propose to extend freedom. My aim is not to pass laws, but to repeal them. It is not to inaugurate new programs, but to cancel old ones that do violence to the Constitution."
    Barry Goldwater

  8. #8
    Join Date
    Feb 2012
    Location
    Moscow
    Posts
    16
    Sometimes you can't come back to the site in a pair of days. In this case I wouldn't install a strainer. One liquid strainer is enough.

  9. #9
    Join Date
    Apr 2010
    Posts
    93
    Ugh... haunting memories of installing and then removing suction driers in TRANE resi units. Especially the newer ~16 SEER R410a units. Who can do a handstand while brazing? Good times.

  10. #10
    Join Date
    Oct 2012
    Location
    Sacramento,ca
    Posts
    196
    Quote Originally Posted by ComfortablyNumb View Post
    Ugh... haunting memories of installing and then removing suction driers in TRANE resi units. Especially the newer ~16 SEER R410a units. Who can do a handstand while brazing? Good times.
    Ditto....this is the main reason i like Rheems rectangle units.

  11. #11
    Join Date
    Aug 2004
    Location
    North Richland Hills, Texas
    Posts
    14,914
    Quote Originally Posted by air1 View Post
    As a matter of best practices I would say that a suction drier should be installed and then removed after the system test clean. But I also think that if you do a acid test before the change out and the system test clean, you could probably get away with nitrogen purge, filter drier, new refrigerant, and a blessing from the dali lama.
    I agree, no point in installing it if the system doesn't need it.

    On a more controversial note, while it is best practice to remove the SL filter drier after it has had time to do its job, if there is not a significant pressure drop through it, it isn't hurting anything if it gets left in.
    If more government is the answer, then it's a really stupid question.

  12. #12
    Join Date
    Oct 2012
    Location
    Sacramento,ca
    Posts
    196
    Quote Originally Posted by mark beiser View Post
    I agree, no point in installing it if the system doesn't need it.

    On a more controversial note, while it is best practice to remove the SL filter drier after it has had time to do its job, if there is not a significant pressure drop through it, it isn't hurting anything if it gets left in.
    Now this may be wrong but i was always taught to measure temperature on each side of the drier to determine if there is a restriction that is not showing itself much on my gauges. How are you measuring the pressure drop? Maybe some piercing valves on the other side?

  13. #13
    Join Date
    Jul 2005
    Posts
    5,571
    Quote Originally Posted by Barrettservices View Post
    Now this may be wrong but i was always taught to measure temperature on each side of the drier to determine if there is a restriction that is not showing itself much on my gauges. How are you measuring the pressure drop? Maybe some piercing valves on the other side?
    The subject here is suction line filter driers. Suction line driers will typically have pressure taps on them. LL driers typically won't.

    As for your initial comment, there won't be a temperature drop across either a suction line drier or liquid line drier unless there is at least some liquid going into it, and a liquid/vapor mixture going out of it. If you have either gas-in-and-gas-out or liquid-in-and-liquid-out, then you get no temperature drop. In either of these two cases you'd typically need some means of measuring the pressure drop directly. Adding a pressure tap is the only practical way to do that in some cases, so don't hesitate to do that when you suspect a restriction and aren't seeing a temperature drop.

    You can have a significant restriction with no temperature drop across it so don't assume that there's no restriction just because there's no temperature drop. IOW, what you've always been told is wrong at face value. There's a lot more to be said, but you can search the forum for threads that cover this topic.

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