alright guys so we're here today to discuss the
TXV and doing a teardown on it I did a live on this a couple of months back on Instagram and
I wasn't able to actually save it the way I was hoping to and so what I'm going to do today
is just a basic teardown and it's just a little small spoiling valve it's actually eight it's got
carriers name on it it's actually a spoiler design carrier just put their logo on it anyway I want
to show you the ins and outs of the actual valve assembly how to disassemble it how to rebuild
it and try to answer any questions I know that I frequently get on so just from looking at it
here this is going to be your liquid line coming into the valve that's going to be a discharge line
coming out on the bottom here not all valves have these but a lot of especially supporting it
so I'm a big fan of spawn as their valves are usually extremely easy to repair and most of
them are adjustable and so on the very bottom here you take this little cap off sometimes these
caps will be an actual hex this one's actually a smooth round cap so you can do finger tight now
you'll see a little adjustment head here this particular one takes an Allen to adjust it and
so what this is for is say you've got a system that's running a super heat that's too high or
too low you can take and adjust this valve to increase or decrease that superheat and so if you
want to decrease superheat you're going to rotate counterclockwise and back that back that down like
the nut out and it's going to look set it's going to decrease your superheat if you want to increase
superheat your just a clockwise and turn it in as you do that's going to restrict the flow down
internally in the valve and it's going to give you more superheat going through your system okay a
big critical thing that's very important when you do that a lot of guys get tripped up on is you've
got to be extremely patient when you're adjusting TX fees especially if you've got a system if you
work some heavy commercial where you may have to TX fees or more in the same circuit that share
the same liquid line it's extremely critical to be very very patient you know you do not want to
rush these adjustments because little happen to use if you do you'll be constantly trying to
adjust it to turn it in and you'll never get it right and then you say you say you do think
you have it right you'll leave and then you'll give a call back later on saying you've got
a compressor down and you get there and sure enough the compressors fried because you flooded
it back or you overheated it because you weren't sending in enough refrigerant through either war
another trick I wanna throw out there early on is if you are having a valve you having to make
a lot of adjustments to and you're seeing that your pressures and superheat and subcooling is
constantly erratic goes up and down up and I'm not really stable at stabilizing very well what
I would suggest to you at that point is go ahead just stop shut that circuit down give it 10 15
20 minutes to fully equalize let it settle out and then try starting it back up because what
can happen is every time you make an adjustment on this valve that whole system has to rebalance
in its refrigerant flow because like I said every time other adjustment is made you're increasing
and decreasing flow through this valve and so as that happens you know those those flow changes
take a minute to circulate through the system and become normalized that's why you see some of
the fluctuation that you do so if you become too fast to react at times what you end up doing to
yourself is the system has so many changes going through it from from the adjustments that it could
literally take a couple of hours for that thing to balance itself back out so if you don't have that
much time to spend to sit there and look at it if you shut it down let it equalize and then bring
it back online it'll kind of give it a restart and you won't have to you can speed up the process and
really see where that valve is that to make sure you're not too high or too low and you're super
heat at that point me personally well I shoot for on super heat is ten to fifteen on just most
applications there are some applications that I work on to where I need a eight to twelve degrees
of superheat and there's others that you know I may want to adjust it to say a fifteen to twenty
personally I do not use a super heat above twenty degrees I hear a lot of guys talk to that think
you know twenty thirty degrees of superheat is is still okay I'm not saying that there's not
applications where that's not used out there but what I am saying is you're gonna put a lot of
stress on your compressor that compressor is going to run a lot hotter your discharge superheat on
the compressor and that's any compressor that's you know scroll reset you name it it's going to
run a lot hotter and so you're just you're gonna create a lot of extra stress on that compressor by
running it that high and so then again the the if you run too low that's kind of an obvious answer
is you're gonna flood your compressor back so that's what I do that's what I personally believe
in I also want to make sure you understand that these things do require a full liquid of column
to come to them with some sub cooling to ensure that they can actually function properly and so
if you're say you've got a restriction somewhere say you're just under charge to begin with and
you're flashing before you actually hit the TXV you're never gonna get a proper run all right
let's get down to the breakdown so this is your lower assembly here this is actual valve body and
so you just take what I like to use I'll take two big crescents click on there I've already broke
this loose these tend to be pretty snug on there just so you know so don't be afraid if you got
little force on it there just a standard thread so we'll just roll this out you want to be very
very careful when you go to pull this apart if you're gonna need to reuse any parts that you
don't lose what's in there so the first thing that's gonna come out this is your whole lower
assembly right here it sits in there just like so okay this is the the rod cap that sits on the
bottom or sits up against the push rod that's in there so a little cylinder rod in the middle so
that push rod is what's actually controlling the flow of refrigerant physically passing through so
that rod sits down inside of here and this is a little foot made to sit inside the spring okay
this Springs pretty dark in my opinion I think that this system probably has some heat issues
there's a lot of things you can determine just by looking at the internal components there's
been numerous TXV I was having trouble with couldn't get it to to properly control superheat
whatsoever I got to open it up and sure enough everything inside is completely black and you get
to looking at it and you realize what somebody overheated the valve so it'll it'll cause a lot
of damage so take the spring out it's also got another bottom adjustment plate if you look down
the side there see it's got a kind of a cone shape that is the actual adjustment screw that's on the
bottle night that's exposed here inside here is a rubber grommet some valves you can actually remove
that grommet and pull this whole stem out this one I was going to have to kind of break it up to
try to do that so I just didn't didn't bother but anyway which so you're adjusting that actual
needle they're coming up which is pushing up against this base here this indented cone shape
sits on top of that and then your spring sits in a seat right here and so if you ever happen to
put one of these together that's how it's an easy way to always know which way it's supposed to go
if you lose track the screen goes on top of that and in this top see it's just like so and I see
your rods gonna go in there so what you're doing when you were just this bottom part is you're
actually adjusting that spring tension and so when you turn it in clockwise to increase
superheat what you're physically doing is you are actually turning up the pressure this
spring is applying to the piston all right to the rod the push rod and so as you apply that
pressure it forces it to close down and reduce flow by reducing flow you're increasing superheat
well the vice versa works the other way around so that whenever you turn it counterclockwise and
you back it out you're decreasing pressure and so by decreasing pressure you're allowing the
the push rod to open up more and allow more flow through decreasing superheat so forth so
that's your basic lower assembly then we will take and take the power head off a lot of times
these power heads themselves you can buy separate at the supply house and so this is what actually
has your thermal control portion so this top head the power head is as we refer to it as charged
with a similar gas – whatever refrigerant it is controlling it is important that you make sure
that this head matches your refrigerant so if you get r22 you need to have an r22 compatible power
head and so as the suction pipe coming out of the evaporator heats or cools it heats and cools
the refrigerant inside of this bulb which then in turn affects the pressure of the bulb and so
as the bulb increases or decreases pressure it's increasing and decreasing pressure on this plate
here and that plate is pushing down on the top of your rod there so that push rod goes all the way
through the body of the valve that's the top side right there and so that's how it's applying its
downward pressure so as temperature increases on the bulb meaning the pipe you superheat is going
up what it does is it pushes harder down on that on that diaphragm in there and it forces the push
rod further down which again that increases flow decreasing superheat and so as this bulb starts
getting cold the refrigerant in there restricts reduces pressure reduces pressure on the diaphragm
the spring pushes the rod closed because the back pressure against the the rod and the diaphragm
and it allows it to choke back on the refrigerant increasing the superheat that's really all it
is there's no more complicated than that if you ever pull a power head off it should be firm it
shouldn't be mushy to where you can kind of feel it playing around in there if you ever do pull
one off and you feel that that's how you know that power head has lost its charge something has
happened that charge you know even when you take it apart should never release and this is all this
both of these use just a like to like metal seal right so this is all brass most of your valves
like this are gonna be a brass tile so there's no special sills or anything but what you have
to be very careful of as all this brass has to be very clean when you go to put it together
because that's how it's actually making its seal is is a like metal to like metal seal so and
you have your push rod which we can actually just push right out the bottom there and that's what
it's doing so this pushrod he sits in there just like so you can see all the way through that
valve and so if you don't you can kind of see it in there you can see where the liquid line is
coming in up inside there yeah there it is let's get shot that's where the liquid line comes in
and pressure hits so what it does is as it needs to reduce flow the diaphragm relieves pressure
the spring pushes up and it pushes this bottom section up against the bottom plate there of the
body and that's helping choke off the refrigerant and in this skinnier section here in the middle as
it needs to increase flow that's along the liquid refrigerant to go by it and so the diaphragm
pushes down against the spring opens up the rod and it allows refrigerant to start flowing
past the pass the push rod increasing the flow no more complicated than that be very very careful
these rods though they're extremely easy to lose they this particular one only goes one way some
of the larger valve designs you'll see there'll be two little rods in there one on each side of
the head be extremely careful not to lose these guys especially if you need to reuse them I know
a very common question I get all the time is okay well if I need to if I want to rebuild a valve you
know where can I do that most of the time what I found is they do technically sell rebuild kits for
TX fees but those kits come and they're usually like a two to three piece set that you have to buy
individually there's not just one master kit that I have seen that the manufacturers produce so what
I found is on jeepers but much easier is I get an exact replacement to the valve that I have and
it's very critical it has to be an exact and I just use all the components out of that new valve
and put it into my my old valve body that's saying the old valve body doesn't have anything wrong
with it which in my experience 98 percent of the time is the case rarely does the body actually
fail or get an issue it's almost always the components of the body and so that's what I end
up end up changing out if I have to replace the TXV what I end up doing most of the time is I pull
the power head the lower simple I pull everything out of it so we're all it is it's strictly the
body and then I'll put the body in place sweat it in and that way I don't have to worry about
any any overheating or anything else happening to that valve giving me trouble down the road another
thing that's really handy is put a little oil or nylon me personally I like to use my log on the
push rods and you reassemble and that helps get some smooth action as it moves up and down help
it give it a little bit longer life okay sometimes these push rods can't actually stick inside that
bore and then you know that's when you'll start seeing some issues with it controlling a lot of
guys I'd like to do the ice bath test on the bulb nothing wrong with that which are really really
when I was first taught that test I was told you know you just watch your pressure to see what your
pressure does you know see your suction pressure fluctuate slightly the issue I ran into that is
it became very unreliable what I've seen is the best test is yes you can do the ice bath but if
you do don't want your pressure watch your actual superheat because you're gonna see your superheat
dramatically swing as soon as you go to do the ice bath because it's gonna think that it's flooding
back and it's gonna try to open up that valve and you're gonna see that the superheat spike up
dramatically so just a little extra piece in there so a lot of guys get confused on how the TXV is
actually what I'll act what all pressures are acting on it so again you got your liquid
line your discharge you've got three main pressure or I guess you can make a case for four
pressures acting on this TXV okay so you've got your diaphragm pressure on the powerhead
pushing down on the push rod alright you've also got your spring pressure pushing up back
against the push rod so you've got your spring and diaphragm pressures you've also got your
equalizing pressure right so the equalizing line goes back to the suction line you want
it sometimes somewhere after the bulb so you want your bulb prior to up you want it upstream
from the equalizing line just in case any liquid does get back through this equalizing line which
can sometimes happen it doesn't affect your your you're sensing bulb temperature reading anyway so
this is applying pressure right here through the port which is helping give pressure back against
the diaphragm okay and then the so recap we got an afferent pressure spring pressure equalizing
pressure which is also up here on the diaphragm and then finally the the last one you can make a
case for is you have the liquid line pressure that is forcing itself down against the bottom of the
actual push rod and then technically you have the suction pressure also pushing or pulling against
the push rod as well from the from the discharge side of it which is right there that really
large opening so you those are kind of just extra pressures but those aren't the official
pressures that we really consider when we start talking about TX fees so yeah that's your basic
breakdown it doesn't really matter what size of t –xv you have some of these if they don't have
the edge Cement stem on them like this one does then a lot of times you know those are gonna be
a fixed t –xv and you're not going to be able to adjust them now it's not that you can't rebuild
them but I would suggest against it those are set by the factory and they they'll they'll still
have an adjustment in there if you ever take one apart it just has a cap on the bottom it doesn't
actually have an adjustment assembly you'll still see that you can still make adjustments it'll have
the same exact dissemble you see here it'll have a spring and the rods and everything but what
it will be doing is the bottom plate that's in there will be set to a certain point on these
inner threads and so that's that you you'd have to count exactly how many threads it took to come
out with it and then whenever you want to put it back together count exactly how many turns to
go back in so it would be a very very precise thing I do suggest if you are doing one of those
just go ahead and replace the whole valve don't worry about taking it apart if you want to take
the power head off and that's it if you can't dam Foss is one that they almost always have the
power heads molded into the valve or sweated into them tore they're not actually removable and so
that's just something unique to Danfoss not that the other manufacturers don't do it at all but
they don't do it near as frequently another big critical thing that I see a lot and I have to
fix a lot behind people is you're sensing bulb here always needs to be on a horizontal if you
ever read the manufacturer's literature on how to do sensing bulbs properly they will tell you
that they want that bulb on a horizontal and they want it in a 10 o'clock or 2 o'clock position
on the pipe so just imagine if you had a pipe there and you imagine a clock on that pipe or the
bottom of the pipe of six the top of the pipe is 12 well you want 10 o'clock or 2 o'clock on that
pipe and that's really what the what they that's the most preferred mining location on a TXV bulb
and I do I do know that then I'll acknowledge that when you start to work with some very large
pipe like say two inches and above you may have to move that bulb down a little bit lower
on that pipe at ten ten or two maybe still a little high because it's such a large pipe but I
personally have never mounted below I say three o'clock or nine o'clock so I know that there are
some some theories out there you can research if you like they kind of read up more about those
now in the event that mining it horizontal is not possible and you have to do a vertical mount
on a TXV bulb you always want to make sure that you mount it with the equal over the would
the pressure tube the pitot tube coming up you never want to mount it with that tube facing
down that the there is this refrigerant that's in there can condense into a liquid and if it does
and it gets and it gets in this tube but in the actual diaphragm it can either cause a failure
or it can it can cause some some weird readings where it's not controlling right down the road
so it is important that you just mount that bulb in a upward position to protect the the diaphragm
in the powerhead okay it's like so that's a very common thing it's also very important that these
get insulated and they're very very tight to that pipe if that bulb is not tight on there or if it's
not insulated it's going to throw off your reading I personally I do not like using zip ties I will
use either a actual bulb mounting kit or if I don't have one I'll get some pipe clamps and even
a bulb this size I'll put a pot clamp on either side of it not one just right in the middle you
can see where this one had one just right in the middle like I said it may be a little overkill
but I don't have issues and my TX fees either the another critical thing is if you've got an
old piece of pipe you want that pipe to be nice clean brass and you want your bulb doing a nice
and clean metal so if you get any corrosion or buildup on either the bulb or the pipe what it can
end up doing is it can act as a barrier between you and the or between the pipe and the bulb and
you're not actually reading the pipe properly at that point another critical thing is you cannot
mount this on any joints you want this to be even if you say you say you have some soft copper and
you've got a little bit of waviness in it you want this to be a straight of piece of pipe as possible
no joints no nothing in the way to cause it to not sit perfectly on top of that pipe okay I've
seen that several times you take and peel back the insulation on TXV and sure enough is sitting
right on top of a joint and it's no wonder your super heat is acting crazy and so because then at
that point it's having a sense through two layers of of coppers that are just one it does make a
dramatic impact on your sensing ability I know that I get into a debate a lot a lot of guys think
that wolf the sensing bulb was in the Airstream he doesn't need to be insulated personally I
say that is false I'd completely disagree with that line of thinking because what the Airstream
is and what this what the the line temp coming off of that evaporator is may be considerably
different at times and so and that becomes the case any difference at that air around it has to
the pipe it's going to impact the the ability for the valve to sense what that pipe is actually
doing so you really really want this bulb to be able to sense as close as possible to whatever
that pipe temperature is so I suggest to everybody matter what the application I know manufacturers
are terrible about sending these pre-mounted with no installation on them at all I highly suggest
you go ahead and insulate that bulb at all times anyway guys that's your basics on doing a TXV
tear down and rebuild and the basic operation of how they actually function like I said I've
I've been using these practices for a number of years they've always done extremely well by me I
have extremely few issues with my TX fees and when I do you know understanding that's the big thing
I try to get guys to understand is understanding how these valves truly work and their in-depth
processes of what they do makes all the world of difference and being easier to diagnose when
you have to and when you need to and so I highly suggest that if you're not that familiar with
TX fees pay attention to this video and then do some reading they do have some very good material
out there oh I will also mention that most of the TXV that work on they have a 4-point adjustment on
the on the adjustment assembly they don't use an allen wrench like say this one does have an Allen
the vast majority you'll run into you will need your service ranch or you can put your service
wrench on it and I do usually what I like to do full rotations is how I count mine so say I'm
running a 30 degree superheat 50-ton system okay if I'm running 30 degrees I'll probably go 3 to
4 full revolutions counterclockwise to decrease that superheat I want to get it down to about 15
right and so I'll do that and I'll give it some time and I'll let it sit and see what it does if
that's enough then I will I'll leave it alone but if I say after making those four revolutions I
go from thirty to twenty all right then I may go another two probably two revolutions maybe three
you know depending on how the system responded and then seeing where I land there if I land at the
fifteen where I want to be and then I'm perfect if not again I'll just make some more adjustments
if I overshoot then no big deal then I'll just go clockwise in one turn or half a turn you know but
I do it in revolutions when you start reading the literature that's how they describe it as well a
lot of guys are get kind of spooked on how much to adjust it and they'll just barely make all these
little tiny turns they don't really do a whole lot of actual adjusting to the pressures in there
anyway guys that's my two cents it's how I do it's how I suggest it I'm always here for questions
if you have any spend time with your family guys
