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  1. #53
    Join Date
    Jul 2003
    Location
    Fort Worth, TX
    Posts
    219
    Mfg could install a liquid receiver and help us out a lot in terms of pumping a system down and over charging possibility. TXVs are the best defense against a low skilled tech when charging.

  2. #54
    Join Date
    Feb 2006
    Location
    Float'N Vally, MS
    Posts
    1,874
    Quote Originally Posted by cuchulain View Post
    we sold a few of the condensers when thy came out. With our corrosive atmosphere they last about 2 yrs before leaks start showing up. Once we started having a run of these leaks we quit selling them. Every once in awhile we'll get a new customer who has one and the first place we go is to pull the leak detector out. If it's in warranty we'll replace the coil and be done with it, until it's out of warranty then we change the condenser.

    Charging is critical. Do it by weight. They give the chart for lineset length/size/rise and how much extra you should add.
    Just got a flyer from Nordyne. They now have "coated" MC coils for corrosive areas like ours. It seems to be like the black coating that Goodman used on their inside coils.....
    Life is too short, Behappy!
    TFMM

  3. #55
    Join Date
    Dec 2003
    Posts
    266
    This is from the new b6 series from nordyne. Its not a mc but what the call there ant eater coil. Has special coating to block the corrosive.



  4. #56
    Join Date
    Feb 2012
    Location
    Opelousas La.
    Posts
    90
    I just picked up a replacement coil for a b3bm-060k and it was a standard tube/fin design. This will be the second coil replacement in this unit since 96. Are their higher seer air handlers going to stick with tube/fin coils?

  5. #57
    Join Date
    Feb 2006
    Location
    Float'N Vally, MS
    Posts
    1,874
    Quote Originally Posted by La Air Man View Post
    I just picked up a replacement coil for a b3bm-060k and it was a standard tube/fin design. This will be the second coil replacement in this unit since 96. Are their higher seer air handlers going to stick with tube/fin coils?
    Tech Service told me last week no MC for 2 speeds. All AHU's A/C and H.P 13 seer have been MC lately. FWIW...
    Life is too short, Behappy!
    TFMM

  6. #58
    Join Date
    Dec 2003
    Posts
    266
    The picture I posted is a variable speed AH and rated for a 16 seer system and its a standard tube/fin design with their special coating. It might be different from supplier to supplier.

    MH

  7. #59
    Join Date
    Dec 2002
    Location
    in a house, Appomattox, Va.
    Posts
    3,431
    I had a 13 seer Gibson this week that I replaced the coil on. the new coil was one of the MC coils, so read the install instructions carefully. Then I called tech help about the piston size- it seems all the 13 seer units (B5BM---) need txv on the evap coil.

    I had to add one because whoever put the system in 5 yrs ago didn't (the copper coil required a txv also). Found the paperwork behind the unit- across tonnages were all txvs. txv is non-bleed, so you also need to add PTC or some other start assist, which doesn't come on a condensor that requires a txv on evap?

    Worked on another Fri, next neighborhood over, same model, no txv either. wonder what that says about all the homes in both these new 'hoods?

    Took care to double check for proper airflow and watch charge carefully. at least this was a r22 system

    I would have thought these coils would have a reverse return setup- headers tapped off opposite ends to get the same distance of travel for all the circuits. Or a tube internal to one header to get the same effect.

    Another concern- if one side of coil gets hotter/colder than the other due to all supplys starting on one side- wouldn't you have noticeably different temps off the right or left side ducts runs off plenum? I've seen offset electric heaters in a/hs do this.

    As far as pump down on MC condensors- if they had a tap on discharge like Trane, you could connect recovery tank there to store extra, and pull it back out by dumping into evacuated lineset after work is done. no recovery machine required at least.
    Col 3:23


    questions asked, answers received, ignorance abated

  8. #60
    Join Date
    Dec 2007
    Location
    houston, texas
    Posts
    3,787
    Quote Originally Posted by BaldLoonie View Post
    I see Dave is joining Carrier, Rheem & McQuay with MC in light commercial.

    http://www.lennoxcommercial.com/landing/environ.asp
    We just did a change out of a store in Austin last month, all Lennox. The 25ton package units had microchannel condenser coils. They looked to be about an inch and a half thick. The also moved the high pressure switches out of the compressor compartment and put them at the liq line drier in the condenser compartment.
    I'm not tolerating Political Correctness anymore, from now on it's tell it like it is.

    Veto Pro Pak - The best tool bag you'll ever own






  9. #61
    Join Date
    Jun 2003
    Location
    Chicago, IL
    Posts
    4,567
    Quote Originally Posted by billygoat22 View Post
    Found the paperwork behind the unit- across tonnages were all txvs. txv is non-bleed, so you also need to add PTC or some other start assist, which doesn't come on a condensor that requires a txv on evap?
    I believe these were all scroll compressors. No start assist required.

  10. #62
    Join Date
    Dec 2003
    Posts
    266
    Quote Originally Posted by billygoat22 View Post
    I had a 13 seer Gibson this week that I replaced the coil on. the new coil was one of the MC coils, so read the install instructions carefully. Then I called tech help about the piston size- it seems all the 13 seer units (B5BM---) need txv on the evap coil.

    I had to add one because whoever put the system in 5 yrs ago didn't (the copper coil required a txv also). Found the paperwork behind the unit- across tonnages were all txvs. txv is non-bleed, so you also need to add PTC or some other start assist, which doesn't come on a condensor that requires a txv on evap?

    Worked on another Fri, next neighborhood over, same model, no txv either. wonder what that says about all the homes in both these new 'hoods?

    Took care to double check for proper airflow and watch charge carefully. at least this was a r22 system

    I would have thought these coils would have a reverse return setup- headers tapped off opposite ends to get the same distance of travel for all the circuits. Or a tube internal to one header to get the same effect.

    Another concern- if one side of coil gets hotter/colder than the other due to all supplys starting on one side- wouldn't you have noticeably different temps off the right or left side ducts runs off plenum? I've seen offset electric heaters in a/hs do this.

    As far as pump down on MC condensors- if they had a tap on discharge like Trane, you could connect recovery tank there to store extra, and pull it back out by dumping into evacuated lineset after work is done. no recovery machine required at least.
    Thats weird. All my nordyne Ah has the txv already installed on the indoor coils. Even the old R-22 ones. THese are all Kelvinator units

    mh

  11. #63
    Join Date
    Feb 2006
    Location
    Float'N Vally, MS
    Posts
    1,874
    Quote Originally Posted by mh heating View Post
    Thats weird. All my nordyne Ah has the txv already installed on the indoor coils. Even the old R-22 ones. THese are all Kelvinator units

    mh
    The MC coils that we have been getting are piston and you have to add the Xvlv.
    Life is too short, Behappy!
    TFMM

  12. #64
    Join Date
    Aug 2004
    Location
    North Richland Hills, Texas
    Posts
    14,915
    Quote Originally Posted by ar View Post
    TXVs are the best defense against a low skilled tech when charging.
    Hey Andy!

    True, but they sure are nice to have for more skilled techs too.
    Also better for the system at our normal summer operating conditions since we spend a lot of time in the "--" range on superheat charging charts.
    If more government is the answer, then it's a really stupid question.

  13. #65
    Join Date
    Dec 2003
    Posts
    266
    Quote Originally Posted by behappy View Post
    The MC coils that we have been getting are piston and you have to add the Xvlv.
    Then it has to be with the suppliers we are using. Different models I guess. More than likely we'll be doing the mc coils soon enough

    mh

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