Page 2 of 3 FirstFirst 123 LastLast
Results 14 to 26 of 37
  1. #14
    Join Date
    Jun 2006
    Location
    Palm Harbor,FL. (moved from PA.)
    Posts
    144
    a little help on determining the flood charge that should be added after a full sight glass on systems with a headmaster control would be greatly appreciated.Also wouldn't adding more charge change my sub-cooling? Is 15-20 F about normal sub-cool for a txv?

  2. #15
    Join Date
    Jun 2006
    Posts
    98
    http://www.sporlan.com/90-30-1.pdf

    Or just charge it on the coldest day of the year.

    [Edited by stat on 06-23-2006 at 12:06 AM]

  3. #16
    Join Date
    Apr 2002
    Location
    Dallas, TX
    Posts
    2,987
    Originally posted by stat
    http://www.sporlan.com/90-30-1.pdf

    Or just charge it on the coldest day of the year.

    I've often thought about adding the above statement to 90-30-1.

  4. #17
    Join Date
    Jul 2000
    Location
    Guayaquil EC
    Posts
    10,314
    Originally posted by Andy Schoen
    Originally posted by stat
    http://www.sporlan.com/90-30-1.pdf

    Or just charge it on the coldest day of the year.

    I've often thought about adding the above statement to 90-30-1.
    That's not a bad idea, Andy. It just might help get the concept across to those who don't quite get it.

    .......but then they're likely the ones that aren't reading 90-30-1 anyways.

  5. #18
    Join Date
    Jan 2004
    Location
    Earth
    Posts
    4,879
    In any case, if they don't gas it to specs, they are sure to be there on the coldest day of the year.
    A Diamond is just a piece of coal, that made good under pressure!

  6. #19
    They only refrigerant you can clear a sight glass on are R22, r12, 502.
    12, 502 are out dated and very seldom you find r22 in a walkin, you do see them but not often

    All blends should never have a clear sight glass, you charge 80 to 85 % of your existing charge when converting to a blend.

  7. #20
    Originally posted by t&mechanical
    They only refrigerant you can clear a sight glass on are R22, r12, 502.
    12, 502 are out dated and very seldom you find r22 in a walkin, you do see them but not often

    All blends should never have a clear sight glass, you charge 80 to 85 % of your existing charge when converting to a blend.
    FALSE!!!!! If you have a receiver, full column of juice.
    On critically charged units with s/g's you will see bubbles.

  8. #21
    Join Date
    Jan 2004
    Location
    Earth
    Posts
    4,879
    Originally posted by t&mechanical

    All blends should never have a clear sight glass, you charge 80 to 85 % of your existing charge when converting to a blend.
    Not true, weight is not the issue. Think volume and density.
    A Diamond is just a piece of coal, that made good under pressure!

  9. #22
    Join Date
    Feb 2003
    Location
    NH & Cebu
    Posts
    1,611
    Originally posted by t&mechanical
    They only refrigerant you can clear a sight glass on are R22, r12, 502.
    12, 502 are out dated and very seldom you find r22 in a walkin, you do see them but not often

    All blends should never have a clear sight glass, you charge 80 to 85 % of your existing charge when converting to a blend.
    Nope, how would you know what the charge was to begin with. 80-85% of what?

  10. #23
    Join Date
    Jun 2001
    Location
    Michigan
    Posts
    12,077
    that percentage bs is bs. A TXV operates on three specific pressures. Most important being a solid column of liquid pressure. If I flash prior to the outlet of that needle I am aboslutely killing my own effort to get it to flash properly and mix through the orfice of that valve or distributor.

    It's common sense. Most people forget, as that liquid goes through that drop of pressure across that needle, were specifically flashing our refrigerant at specific points so as to get the proper liquid vapor mixture so the coil and the air passing over it can properly and efficiantly remove the heat it was designed to do. If you flash prior to that, "flashing or flash gas" being present in your liquid prior to hitting that valve, you just took away some of the valves responsibility to properly regulate the superheat in that coil.

    Second is Bulb pressues, third, outlet. I have never ever ever ever ever had an issue with over charging a unit with all this new crap by assuring a subcooling value giving me a full column of liquid. A receiver allows me this flexibility. The receiver level changes up and down as the expansion valves feeds, allowing me to feed full column of liquid through out all loads conditions on that coil. End of story.

    And beyond that. Critically charged systems employing cap tube and fixed orfice, well think about it. It may end up being 85% OF THE ORIGINAL OZONE DEPLETING GAS, but, superheat is superheat and there is no weight scale accurate enouph to peg the bullzeye like you are able to when doing your superheat measurment to insure ample charge and that coil is operating at it's optimum ability to absorb heat.

  11. #24
    Join Date
    Jun 2001
    Location
    Michigan
    Posts
    12,077
    inadequate charge by method of 85% is also going to play on issues of defrost, coil efficiencies ect. It's theory through and through.

    I will tell you what. If Andy tells me I am wrong. I will buy you all a case of beer.

    So Andy?

  12. #25
    Join Date
    Jun 2001
    Location
    Michigan
    Posts
    12,077
    and as far as air conditioning goes. Most common in design is nothing more than a simple refrigeration man's thinking. Our optimum dishcharge air temp is 55 degrees. Almost all normal AC coils are set up for a plus 40 saturated suction temp with a 15 degree td giving you the 55 DA temp. 15 degrees will do great things dropping sensible temp and deal with latent load.

    This is benchmark engineering used for many years. An air conditioning system is a refrigeration systems. Period.

  13. #26
    Join Date
    Jun 2001
    Location
    Michigan
    Posts
    12,077
    Originally posted by stat
    Do not charge by sub-cooling. Add refrigerant until you can see it flowing through the sight glass. Keep adding refrigerant until the sight glass clears. Let the system run for a few minutes to make sure the sight glass stays clear. Add more if necessary. At this point add flooding charge if you have a flooding control valve.

    Many of you guys think this headmaster is confusing. It's not.

    The TX valve wants to see whatecver it's set up for. Most TXVS are rated at a certain capacity of tons depending on temp of full column of liquid and delta P. Block the condenser to clear the glass to give you 95 degree liquid with a 10 degree subcooling. Your done and you will have zero issues with being low on charge in lower ambients. You will not over charge. You won't overcome the TXV's ability to be a constant superheat mechanism by giving 10 degrees of sub.

    Racks are a bit different but not by much.

Page 2 of 3 FirstFirst 123 LastLast

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
Comfortech Show Promo Image

Related Forums

Plumbing Talks | Contractor Magazine
Forums | Electrical Construction & Maintenance (EC&M) Magazine
Comfortech365 Virtual Event