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  1. #1
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    Newbie question on gas recovery



    Hi everyone

    First post, and newbie refrigeration engineer here. I qualified just before Christmas so I am just finding my feet hence why this is probably a very simple question.

    I have been tasked with decommissioning an old Denco R22 water chiller but am struggling to work out how to connect my gauges, and therefore my recovery machine, to it. It doesn't seem to have any service valves anywhere, just these schrader-type connections on the high and low pressure sides of the compressors. I seem to remember from my course that we used one of these for the vacuum gauge when pumping down the system.

    So my question: can I use these valves for refrigerant recovery?

    If I can, do I need some kind of adapter to push down the valve or will my standard hoses work? I've got a Javac gauge set and the standard hoses that came with it if that makes any difference.

    If not, what should I be looking for instead to connect to?

    I've attached a photo. Note that it has been sat outside for a while hence the rust!

    Would appreciate any pointers.

    Thanks, Chris
    Attached Images Attached Images



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    Re: Newbie question on gas recovery

    Hi Bigcv and welcome to the forum.

    The standard hoses for your manifold will have shrader depressors in one of the ends. Technically you can use these to connect to the system BUT this takes a lot of practice before you can do it safely without risking burning yourself on liquid refrigerant and loosing gas.
    The safer option is to use Quick Couplers on the end of your hoses and if you are looking at recovering a lot of refrigerant then the fastest would be to connect your hoses to the system using core removal tools.


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    Re: Newbie question on gas recovery

    Hello bigcw.
    Yours is what used to be a common dilemma, where old R22 systems were built with little or no access points.
    Because back in the dark ages 22 was just blown off. (Released to atmosphere.
    Since then system designs have evolved to comply with the new legislations!

    Looking at the state of the system I wonder if any refrigerant is still in the system?

    Quick couplers are indeed the way to go.
    Given your lack of suitable valve locations you could use a line tap attachment,
    Just google "Refrigeration Line Tap" and you will see what I mean.
    A 1/4" tap on the Liquid line (Say by the filter drier- Condenser side would be good)
    They are listed as around 5.00 and are reusable. So they are a useful addition to the toolbox.
    Grizzly
    Despite the High Cost of Living it still remains Popular!

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    Re: Newbie question on gas recovery

    .

    Schrader type connectors are extremely slow for refrigerant
    recovery due to the restriction of the valve. The kwick couplers
    are good for measuring pressures and such but again slow the
    refrigerant transfer down.
    There are schrader valve removal tools available and they allow
    you to pull the valve out of the scrader fitting and then you can
    move refrigerant as quick as possible.

    The hoses you have will have schrader depressors on the 45 degree
    angle end and they will work.

    Rob

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    .. ... -. .----. - / -- --- .-. ... . / -.-. --- -.. . / --. --- --- -..

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    Re: Newbie question on gas recovery

    Hello bigcw

    What did you qualify as before Christmas?
    I'm back on the Pale

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    Re: Newbie question on gas recovery

    Thanks for the advice everyone.

    Those line tap things look like a good way to go. I assume they have a valve on them so the gas doesn't escape in the time between putting them on the line and fitting the hose?

    Intrigued by this tool that can remove the schrader valves. Surely this can only be done once the system is empty as the gas would pour out if the valve was removed?

    frank: by 'qualified' I mean passed the f-gas course (class 1 C&G if that makes any difference). I'm only working on my own equipment at the moment; I own a business in the telecoms sector that uses a lot of air conditioning equipment.

    Cheers, Chris

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    Re: Newbie question on gas recovery

    Mutters quietly, "Boy he's got a lot to learn", and sits back in the corner again.
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    Re: Newbie question on gas recovery

    Quote Originally Posted by Brian_UK View Post
    Mutters quietly, "Boy he's got a lot to learn", and sits back in the corner again.
    Don't I know it!

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    Re: Newbie question on gas recovery

    Quote Originally Posted by bigcw View Post
    Thanks for the advice everyone.



    Intrigued by this tool that can remove the schrader valves. Surely this can only be done once the system is empty as the gas would pour out if the valve was removed?



    Cheers, Chris
    No it is a valve arrangement that allows the valve core to
    be removed while the system is still pressurised with
    refrigerant.

    By attaching and opening the valve in a select way the core
    can be removed while refrigerant is present.

    Rob

    .
    .. ... -. .----. - / -- --- .-. ... . / -.-. --- -.. . / --. --- --- -..

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    Re: Newbie question on gas recovery

    Thanks for explaining, Rob.

    Sorry to sound dumb (as above, I'm a complete newbie!) but is this the right thing?

    https://www.airconspares.com/product...over-Installer

    *Admin note: I have no affiliation to that company, it just came up when I searched

    Are they all the same? As in there are no 'different' valves that this won't get out?

    Do I need to get one for each side? When we did recovery on the course we pulled from both the high side (with the valve just cracked open slightly to only get gas out) and the low side? Presumably I can just pull from one side and just suffer the extra time it will take?

    By the way, thanks again for the advice everyone.

    Chris
    Last edited by bigcw; 27-02-2017 at 11:53 AM.

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    Re: Newbie question on gas recovery

    Yes thats the beastie, make sure that the one you get has both adapter sizes, R410a and regular. Having more than one is always good.
    Brian - Newton Abbot, Devon, UK
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    Re: Newbie question on gas recovery

    Thanks Brian. Have ordered one, hopefully it will be ok just pulling gas from one side. If it takes a while I don't actually mind too much as I'll be on site doing other jobs anyway so can just leave it running.

    Don't have any R410a stuff yet but keeping an eye on eBay for a decent set of gauges at a good price. All I have done so far is R407 or R134a (the latter to gas down a car system before I took it to bits)

    Chris

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    Re: Newbie question on gas recovery

    You could close service valve, remove the shrader core if you must, attach line without quick coupler and then open the valve again. Apply voltage to expansion valve or use magnet to open it so that you can recover both sides of the system through your service valve. Quick couplers are a gimmick, use the valve
    Last edited by Contactor; 03-03-2017 at 11:12 PM. Reason: Valve

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    Re: Newbie question on gas recovery

    That thing is a service valve, remove plastic valve seal cap to gain access to valve stem. You often find service valves stuck on the side of compressors, you might get some oil but you can recover from anywhere. If its a chiller you might find another shrader by the expansion device, often used to check depth of vacuum, but you could recover from there as well
    Last edited by Contactor; 03-03-2017 at 11:17 PM. Reason: Vulva

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    Re: Newbie question on gas recovery

    Thanks for all the advice. Did the job on Saturday. The schrader tool worked a treat and I recovered about 7kg of R22 out of it.

    Interesting point: the data plate on the unit said 1 circuit with 1.4kg of R22 but it was not the case. The system very clearly had two large hermetically sealed compressors, two separate circuits, and I got about 3.5kg out of each one. Is it common for data plates to be 'wrong'?

    One idea I had: could it be that the unit was retrofitted with a different gas at some time in it's life? Do keep in mind though that the building has been mothballed since 1990. I've no idea if R22 was still current back then and/or whether that is before people knew/cared about how bad it was for the environment?

    Chris

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