What's That Gas?
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  1. #1
    Join Date
    Feb 2012
    Location
    NY
    Posts
    128

    What's That Gas?

    Hello - I'm new here. I'm an HVAC cross-over. Long awaited, now I think I'm ready and the opportunities exist. I'm decent with HVAC, I don't like to be hurried, I like to be careful and certain before throwing that switch. I like controls and logic problems. I like dirty hands.

    I've been reading many posts here. Needless to say the naming of so many different refrigerants is daunting and leads me to wonder:

    When you walk up to a reach in refrigerator at a restaurant for the first time and find that it's old, it's grimy, it smells bad, and it's warm - how do you now the gas is really the name plate stated R12? I mean surely some one has worked on this thing. Do you pull out the mystery gas and start anew?

    That lead me to the follow-up: so how many recovery tanks are on your truck??? One for each refrigerant? Really?

  2. #2
    Join Date
    Jun 2013
    Location
    Kansas city
    Posts
    31
    you can hook up gages and check against a press temp chart or get the fancy digitals and they will tell you. Time for new toys mabey.

  3. #3
    Join Date
    Feb 2009
    Location
    Tallahassee, FL
    Posts
    5,974
    Digital guages don't really tell you what it is. They do have all the pt charts in them so its a little easier.

    Also National refrigerants has "one shot " recovery tanks for about $40 if you need to recover a unpopular blend.

  4. #4
    Join Date
    Jul 2012
    Location
    Western KY
    Posts
    1,221
    The before mentioned methods will tell you what it is, most of the time. So once you know be a dear and grab a paint marker. :-)

  5. #5
    Join Date
    Feb 2012
    Location
    NY
    Posts
    128
    Thanks all. I'm familiar with TP charts but in AC it would be hard to miss the difference between R22 and R410a. But this world seems to have many refrigerants and refrigerant blends which depending on the operating temp have crossover values that I imagine would make it difficult. So I guess you're all saying that if it's way off the R12 TP chart then someone has either mixed or replaced and not left a tag.

    Also appreciate the mention from "SBKold" about the recovery tanks. I have a reusable one for both R22 and R410a but they were both really expensive.

  6. #6
    Join Date
    Aug 2013
    Location
    Pennsylvania
    Posts
    50
    one thing to be wary of when you are looking at units to determine the refrigerant: make sure it has the proper charge weight in it. otherwise it will throw off your reading.

  7. #7
    Join Date
    Sep 2008
    Location
    Western PA
    Posts
    25,335
    Quote Originally Posted by demidos89 View Post
    one thing to be wary of when you are looking at units to determine the refrigerant: make sure it has the proper charge weight in it. otherwise it will throw off your reading.

    Not really.

    As long as there is a quantity of liquid in the unit, the saturation temperature will be correct.

  8. #8
    Join Date
    Aug 2013
    Location
    Pennsylvania
    Posts
    50
    i mean when its nearly out of gas. but at that point i guess it would be best to pull the charge and update if possible.

  9. #9
    Join Date
    Oct 2008
    Location
    mid-Tennessee
    Posts
    681
    Quote Originally Posted by Tinbrook View Post
    When you walk up to a reach in refrigerator at a restaurant for the first time and find that it's old, it's grimy, it smells bad, and it's warm - how do you now the gas is really the name plate stated R12? I mean surely some one has worked on this thing. Do you pull out the mystery gas and start anew?
    After you know what the plate says, verify...verify. Check the condenser sticker for oil type. If a TXV, check it's marking for what it's set up for. Look for any markings (with a "sharpie" or any added stickers) on or around the condensing unit that might cue you in on whether/what refrigerant someone used in it. Lastly...system pressures. Do they match what you'd expect for that nameplate refrigerant? Of course, if it's low due to a leak, this pressure verification won't really do any good. Doing a "static" pressure reading of system is most accurate, there's gotta still be some liquefied stuff still in the sytem for that to work.

    Quote Originally Posted by Tinbrook View Post
    That lead me to the follow-up: so how many recovery tanks are on your truck??? One for each refrigerant? Really?
    The most common three refrigerants I saw were R134A, R22 & R404A - so tank for each of those. Then I kept an empty, undedicated (yet) tank on the truck for "whatever" I might run in to.

    So....4.

  10. #10
    Join Date
    Dec 2010
    Location
    Howell, MI
    Posts
    5
    If the label remains R-12, odds are it is a 12 drop in. 401 (MP-39) or 409.

  11. #11
    Join Date
    Sep 2008
    Location
    Western PA
    Posts
    25,335
    Quote Originally Posted by demidos89 View Post
    i mean when its nearly out of gas. but at that point i guess it would be best to pull the charge and update if possible.
    Oh yeah. For sure.

  12. #12
    Join Date
    Aug 2013
    Location
    Pennsylvania
    Posts
    50
    also some people replace it with R 414b however it probably wont last long due to the fact it contains R22

  13. #13
    Join Date
    May 2013
    Posts
    47
    Why wont it last long? (414b)

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