freezer giving me hard time.

[wannafreeze]

aja2419zxa compressor.
trenton tlk160 evap.
Two door freezer.Label says 134a.Two steel door upright freezer for donuts etc.
A couple of years ago I told the owner that the freezer looks like a mismatch. At that time I was able to make it work with the refrigerant I put in.(must had been 404a). They weren't interested in conversion.It worked fine for a long time until now.
Two weeks ago when I was out of town they had to call some other guys for this freezer, they came a few times. Brought a new 404a tank. The tank was maybe 10# and left at the store after they had a fight with the store manager. No cap tube was changed they probably didn't even realized it was a mismatch. When I got there the freezer wouldn't go low enough (16F) and with the typical 404a head pressure suction was high to pull it lower. I thought it was obvious. I replaced the refrigerant. With some lower head pressure I aimed a lower evporation temperature. Couldn't get it work right. Gave them my price for replacing the cap tube with my guarantee that if it won't work I don't charge anything. While I was doing it I changed my mind and decided to convert it to txv without changing my price which is not my main concern any more.
I left the c032 cap filter drier I originaly installed for the new cap tube in the liquid line hoping that it would be alright for the 1/4 ton zp txv, which I think is not the cause of the problem I am facing now. After that filter/drier I installed a nice size (not too big, not too small, a couple of LBS ) receiver tank, made a new 1/4 line for txv.
The suction size coming out of evap is a 3/8..
I put 3 cases of water bottles inside. Over night it only pulled down to +20F. Txv was starving the evap. With about 250/23 psi pressures. Suction line was too warm, didn't even need to measure. Nothing obviously wrong as far as heaters being on, fans turning in the wrong direction, coils being dirty etc. Adding a little 404a just ends up in being pumped down. There is no shortage of it. No sight glass. To get some lower superheat at the bulb spot opened the valve, ended up opening all the way. Came back a few hours later. Colder box (10 F), with about 15 * SH at the suction line a few feet out of the evap.( outside of box ).

Decided to replace the txv again. It seems like without adjusting the stem, it's behaving the same way. Starving the coil, temperature not moving like you would see normaly in a freezer. Freezer insulation, gaskets etc. very well. Everything seems functional.
Before I put a 1/2 ton zp in there I want to ask, do you have any idea why a 1/4 ton 404a zp would starve that coil? I blew throug the coil with nitro, nothing strange there. I am just so annoyed by getting nailed by a freezer like this, I can't except it. Like I said it's not about money anymore. The coild btuh rating should not have anything to do with the type of the refrigerant, would it? And that c032 cap f/d is before the receiver tank with no apperant restriction. The heavy frost starts at the txv anyway. It just acts like it's too small to flood the coil. But why would it feed it more when I opened it up all the way? It went from 20 psi to about 35 psi when I opened it. I don't think I am rushing in my adjustment time either. I give it enough time to do something.

O well, something had to break the monotony..

PS. Maybe it needs to be externally equilized? Did I just find the answer ?

[icemeister]

The compressor is rated for about 1710 Btuh at -20ºF on R404A and I assume the coil is rated at 1600 Btuh at a 10ºF TD so that looks OK to me.

The 1/4 ton TEV should be more than adequate for that capacity. You shouldn't need an externally equalized valve if you don't have a distributor, so I doubt that is in play here.

Did you clean the TEV inlet screen?

EDIT: Ooops, I see you replaced the valve and got the same results. Is the element an RZP or SZP for R404A?

[wannafreeze]

The compressor is rated for about 1710 Btuh at -20ºF on R404A and I assume the coil is rated at 1600 Btuh at a 10ºF TD so that looks OK to me.

The 1/4 ton TEV should be more than adequate for that capacity. You shouldn't need an externally equalized valveif you don't have a distributor, so I doubt that is in play here.

Did you clean the TEV inlet screen?

Yes both txv s are new and the screens are clean. I checked the one I installed yesterday to see if that's what happened. That coil has quite a few turns. I am going to put an ext. eq. txv..

I pumped down the system a few times. Compressor seems to be okey. There is no reason for the txv to starve, it got me..

Liquid reaches the txv..No head pressure issues..

[wannafreeze]

The compressor is rated for about 1710 Btuh at -20ºF on R404A and I assume the coil is rated at 1600 Btuh at a 10ºF TD so that looks OK to me.

The 1/4 ton TEV should be more than adequate for that capacity. You shouldn't need an externally equalized valve if you don't have a distributor, so I doubt that is in play here.

Did you clean the TEV inlet screen?

EDIT: Ooops, I see you replaced the valve and got the same results. Is the element an RZP or SZP for R404A?

I think the valve name starts with S. let me run out to my truck..

[wannafreeze]

FS-1/4-ZP

[icemeister]

FS-1/4-ZP

The S indicates it's an R404A valve alright. It should work.

At this point, I'd add a pressure tap or a SG ahead of the valve to confirm a solid column of liquid.

[wannafreeze]

The S indicates it's an R404A valve alright. It should work.

At this point, I'd add a pressure tap or a SG ahead of the valve to confirm a solid column of liquid.

Ice, receiver tank outlet is liquid with a lookwarm liquid line (filter is before the tank.) and a 250 psi head pressure. Adding a little more only pumps it down. The liquid is subcooled and line is new. But it's worth investigating that further..

[icemeister]

Re-reading all this, I don't understand the part about if you add more refrigerant the system pumps down. That isn't making any sense to me. Can you expand on that a bit?

[wannafreeze]

Re-reading all this, I don't understand the part about if you add more refrigerant the system pumps down. That isn't making any sense to me. Can you expand on that a bit?

I thought I wasn't clear with that. If I add a little 404a to make sure I am not short (because I don't have a moisture indicator) it condenses it back to around 250 from a little higher start pressure.

[wannafreeze]

Ice, I have to go.
But I am taking my computor with me. I will check the responses in an hour.
thanks for being there..
al.

[icemeister]

I'm still not sure exactly what you're saying there.

When you add refrigerant, does the suction pressure go up into the MOP range of 30-35 psig or does it go down for some reason? If it rises, it would appear you were just short on gas.

Add a SG and see where you're at.

[wannafreeze]

I'm still not sure exactly what you're saying there.

When you add refrigerant, does the suction pressure go up into the MOP range of 30-35 psig or does it go down for some reason? If it rises, it would appear you were just short on gas.

Add a SG and see where you're at.

No, I meant the head pressure is alright. It's not like it's short on gas or overcharged. Maybe it was redundant and confusing to mention. You know if I had a 220 psi head pressure and added more refrigerant and went up to 250 I could conclude that I was short. But that's not the case. That's what I tried to say with the opposite occurance.

[wannafreeze]

the reason I don't suspect any restricton or being short of gas is because when I opened the valve all the way it responded with a 15 psi increase, and less superheat.
Actually it may have increased the back pressure more, this is a zp valve..

[icemeister]

the reason I don't suspect any restricton or being short of gas is because when I opened the valve all the way it responded with a 15 psi increase, and less superheat.
Actually it may have increased the back pressure more, this is a zp valve..

That is telling us that while the coil was obviously starved for refrigerant the TEV was not fully open at the time.

You may want to check for a high pressure drop through the evaporator. There shouldn't be much as the Trenton TLK is designed for internally equalized TEVs. If there is, you may have some junk in there creating a restriction causing the valve to "think" the superheat is OK.

[wannafreeze]

That is telling us that while the coil was obviously starved for refrigerant the TEV was not fully open at the time.

You may want to check for a high pressure drop through the evaporator. There shouldn't be much as the Trenton TLK is designed for internally equalized TEVs. If there is, you may have some junk in there creating a restriction causing the valve to "think" the superheat is OK.

Why couldn't I say it like that? All the while I was trying to get there.
Before I installed the second fs-1/4-zp i put nitrogen from the suction service valve towards the txv outlet and loosened up the flare nut while trying to catch anything that may come out. All I got was nitrogen coming out with a good force.
I bought the ext eq. txv already. I have to run 3 calls today, if I get lucky and finish fast i may spend the night there again. If that doesn't work and I don't get another clue, I already cut my 29" supco #2 cap tube..
talk to you later.:)

[Joe Harper]

I left the c032 cap filter drier I originaly installed for the new cap tube in the liquid line hoping that it would be alright for the 1/4 ton zp txv, which I think is not the cause of the problem I am facing now.


Are you sure????

[crackertech]

Are you sure????


I with Joe ya might wanna check that drier out.

[wannafreeze]

I with Joe ya might wanna check that drier out.

At 250-270 psi head pressure (downstream of drier), I had full liquid to the txv. No sensible temperature change across it. Also that drier is at the outlet of the condensor coil, before the receiver tank. To bump the head pressure up from 250 to 270 ( reading from the receiver valve ) I had to add quite a bit 404. If the drier were restricting I know what kind of motions that compressor would go. The restriction is definetely starting from the txv. Something is causing it to clamp down. (I tried two internally eq. and one externally eq..)
Again that filter/drier is upstream of the tank and tank pressure is 270 psi. It would be like plugging the condensor tubing and trying to put a lot of refrigerant in it.

[wannafreeze]

I think Ice is right on that evap tubing being restricted. Something is wrong with it and with a high pressure nitrogen flow through it it can't be determined, but at the lower operating pressures the restriction might matter.

I went ahead and installed an externally equilized txv. Same thing. The coil is greatly starved. Something is wrong with the evap tubing, I won't even try to install the cap tube I was originaly going to install.

The head pressure tends to stay at like 250. I raised to to 270 at room temp. I confirmed liquid to the txv at 270 psi, liquid line also cool. Low side around 15 psi with a lot of evap superheat and heavy frost from the txv on, and few tubes, and the rest warm. The condensor is not blowing out warm air.

[wannafreeze]

one more question: the suction line is 3/8". the outlet of evap is not..

[VTP99]

Did you test the pump ?
Is there a 3/4 roto lock on compressor ?

[wannafreeze]

Did you test the pump ?
Is there a 3/4 roto lock on compressor ?

Pump pulls down to 10-15 vacuum and holds it there, I did it a few times..there is a roto lock. I have to check the pipe size again.

[nchvac]

Maybe I missed something. What is the superheat and subcooling temps with the current box temp?

[VTP99]

I hate freezers always problematic. Got to go now but will think about your thread and get back. Good luck and remember persistence always pays off.;)

[wannafreeze]

Maybe I missed something. What is the superheat and subcooling temps with the current box temp?

The evap superheat is high, I took a few measurements to remember any exact number. It could go over 50* evap SH, with an untempered valve. With the first internaly equilized valve , stem all the way out, the next day, with box at steady +20*, 15* SH at 3 feet from the evap. There is enough subcooling not to need to measure it. The problem is too obvious not to get fixed on these numbers. Many times a visual check told the coil is starved. And I confirmed a good subcooled full liquid refrigerant right to the txv inlet.

[wannafreeze]

I wonder where it was crimped at the outlet of the evaporator to braze the 3/8" suction line into the evaporator if the line size is even more reduced..

[icemeister]

Before replacing the evaporator I think you should verify the suspected restriction by adding a pressure tap immediately after the TEV. It shouldn't take to much to do that and then you'll know for sure whether the coil is the problem or not.

I'm wondering if there may be a restriction where you removed the cap tube and brazed in the TEV outlet. Excess solder maybe? I know it's grasping at straws, but it's possible.

I don't believe the suction line sizing is a significant problem here. First, since it's the same size it was before when the system performed OK and second, according to the limited line sizing info I have for such a small load the pressure drop should only be 1-2 psi with 3/8"OD tubing.

[cold spell]

Maybe try a bigger dryer with the outlet facing down. This will act as a reciever, and you will get less flash gas at the valve

[wannafreeze]

Before replacing the evaporator I think you should verify the suspected restriction by adding a pressure tap immediately after the TEV. It shouldn't take to much to do that and then you'll know for sure whether the coil is the problem or not.

I'm wondering if there may be a restriction where you removed the cap tube and brazed in the TEV outlet. Excess solder maybe? I know it's grasping at straws, but it's possible.

I don't believe the suction line sizing is a significant problem here. First, since it's the same size it was before when the system performed OK and second, according to the limited line sizing info I have for such a small load the pressure drop should only be 1-2 psi with 3/8"OD tubing.

That's why i can't even offer a new evaporator. Because I can't be sure at this point.
The old cap tube connection, I cut that out. There was a flare nut already on the tubing. Also I blew the coil out with nitrogen from the compressor side. No apperant problem there. Adding a pressure tap won't be that easy. Since this is not a WIB it would not be easy to see the operating pressures. But I could probably braze a 3/16 tube and run it outside the freezer to measure that pressure. At this point I was giving up on this and after taking my receiver tank and txv I was going to install the cap tube I already cut for this..
That suction line performed fine, but with a cap tube..
I might muster more energy by saturday and decide to experiment further.
I just hope it's not something stupid I missed and somebody else comes and takes care of it.

[icemeister]

One thing that still bothers me here is we're still not 100% certain you're getting a solid column of liquid to the TEV. You said you checked at the outlet of the filter-drier but you didn't say you checked at the inlet of the valve. Can you install a SG at the receiver outlet or maybe get a subcooling reading at that point?

Also, I'm puzzled as to why the valve is slamming closed when you add refrigerant. I checked it's capacity and with 100ºF liquid and 100 psi pressure drop it'll do .27 tons. If you factor in say 90ºF liquid temperature and 235 psi pressure drop (250#-15#) you're up to around .40 tons or 4800 Btuh. perhaps, being that oversized it can't throttle, so it's possibly either wide open (with insufficient liquid feed) or fully closed when the valve sees a big rise in pressure and the bulb senses the rapid drop in temperature. I dunno.

An FS-1/8-ZP would actually have been a better choice i think. Its capacity would be about 2300 Btuh or so.

[stonewall]

Try it with out the pressure limiting power head.

[powell]

aja2419zxa compressor.
trenton tlk160 evap.

Two door freezer.Label says 134a.Two steel door upright freezer for donuts etc.



If the freezer label reads that it is a R134a system then the original compressor would have been a AJA2419YXA not a AJA2419ZXA.

Either the compressor has been chaged, correctly or incorrectly, to a "ZXA" or you might have read the number wrong.

I'd check this out.

If it was changed to a "ZXA" then the original cap tube would have been incorrect, but you said it worked but you don't remember if you used R134a or R404A.

But, it should work now if it's a "ZXA" and the TEV is R404A and your using R404A.


Hmmmmm,

If all is matched properly then I suspect a bad pump.

[VTP99]

CALLING OUT TO ANDY,
Where are you brother ? We need a valve sizing here & to pick at that Sporlan brain. :ghug:

[crackertech]

CALLING OUT TO ANDY,
Where are you brother ? We need a valve sizing here & to pick at that Sporlon brain. :ghug:
Just in case you missed this thread I"ll bet Andy is a tad bizzz right now.

http://hvac-talk.com/vbb/showthread.php?t=508202

[wannafreeze]

If all is matched properly then I suspect a bad pump.

I told them (customer) today that even though I can't prove it, the pump loses efficiency at a cirtain point. I have a good feeling changing it will take care of it. But I won't experiment with my money. Basicaly if they give me the full amount in cash I will go buy and replace compressor.
In any case; cap tube or the three txv s I tried, the box gets down to 25-30 *F quiet fast. The problem starts from there on. It's gotta be the pump.

ps. the pump is 404. it also has a color coded sticker on it. ZXA

[VTP99]

Crackertech
I know Andy switched gears in post #7. I was thinking maybe he might pop in now and then with all that Sporlan knowledge .;)

[crackertech]

Crackertech
I know Andy switched gears in post #7. I was thinking maybe he might pop in now and then with all that Sporlon knowledge .;)
10-4 I"m sure he will as soon as he get's settled in.

[VTP99]

I'm with Ice in the thinking no full column at TXV or wrong TXV size.

[wannafreeze]

One thing that still bothers me here is we're still not 100% certain you're getting a solid column of liquid to the TEV. You said you checked at the outlet of the filter-drier but you didn't say you checked at the inlet of the valve. Can you install a SG at the receiver outlet or maybe get a subcooling reading at that point?



Ice, maybe you skipped it on some of my later responses I said it. I confirmed liquid to the inlet of txv at 270 psi and with no condensing problem. The refrigerant is definetaly not short. And it's at the flare inlet connection.( cracked the flare )

[nchvac]

I am trying to figure out the logic behind saying a compressor is bad when we are seeing up to 270 psi on the head, proper subcooling(which could be restricted subcooling) and a box that is droping in temp. You also confirmed the valves are holding. What is the amp draw? I say with proper amp draw, which has to be with a head that high, you are pumping.
If you are pulling down the box temp, then you are decreasing your head pressure. A decrease in head pressure will lower refrigerant flow across a restriction or partial restriction, which could look like a lose of efficency at that point. Pull the drier and fix the problem. Everything seems to point to the drier. We have liquid there, but do we have the pressure to push it after the restriction?

[Joe Harper]

Everything seems to point to the drier. We have liquid there, but do we have the pressure to push it after the restriction?

It cant be that. I already said that, and no one ever listens to me :)

[wannafreeze]

I am trying to figure out the logic behind saying a compressor is bad when we are seeing up to 270 psi on the head, proper subcooling(which could be restricted subcooling) and a box that is droping in temp. You also confirmed the valves are holding. What is the amp draw? I say with proper amp draw, which has to be with a head that high, you are pumping.
If you are pulling down the box temp, then you are decreasing your head pressure. A decrease in head pressure will lower refrigerant flow across a restriction or partial restriction, which could look like a lose of efficency at that point. Pull the drier and fix the problem. Everything seems to point to the drier. We have liquid there, but do we have the pressure to push it after the restriction?

Well, I already said that the drier is upstream of the receiver tank. 270 psi is taken from the receiver tank, thus downstream of the drier.

[nchvac]

I have to ask wanna something. I will say upfront that wanna is a fine person and has been very helpful to me, and I am hopefully not going to make him mad by asking this. Why would you change out 3 txvs with the knowledge that someone else worked on the unit and put refrigerant and probably moisture in the system, and not change the dryer? Isn't it good practice to change the dryer anytime we open a system? I absolutely will not leave in an old dryer. I learned this working on Trane units. The filter dryers will pull in moisture when the system is open and that moisture will cause trouble in the dryer.

Have we confirmed a suction pressure?

[wannafreeze]

An important clue might lie in the fact that the box cools down from room temperature to 25-30 *F with a good speed, than stops pulling down.

[nchvac]

But what is the head pressure when it stops pulling down? What I am thinking is that at the lower head pressure, you aren't pushing liquid through the tev when you should be. In other words it seems that the liquid is laying in the line instead of being pushed through the tev. This is why you have so much subcooling.
I bet that if you were to block the condensor and raise the head, you would pull the box down to further because you would be pushing the refrigerant through the tev.

[VTP99]

Ice, maybe you skipped it on some of my later responses I said it. I confirmed liquid to the inlet of txv at 270 psi and with no condensing problem. The refrigerant is definetaly not short. And it's at the flare inlet connection.( cracked the flare )

When you say (cracked the flare) was this your confirmed liquid test ?

[wannafreeze]

I have to ask wanna something. I will say upfront that wanna is a fine person and has been very helpful to me, and I am hopefully not going to make him mad by asking this. Why would you change out 3 txvs with the knowledge that someone else worked on the unit and put refrigerant and probably moisture in the system, and not change the dryer? Isn't it good practice to change the dryer anytime we open a system? I absolutely will not leave in an old dryer. I learned this working on Trane units. The filter dryers will pull in moisture when the system is open and that moisture will cause trouble in the dryer.

Have we confirmed a suction pressure?

nchvac, when the thread gets longer and longer some of us miss some points the op already made.
The filter drier was installed by me when I was going to install a 29" #2 supco cap tube. On a second thought I had a feeling that the other cap tube was not restricted and the freezer worked with it for 3 years that I know.I had a bad feeling about cap tube replacement.I made a U-turn a decided to install a txv and the receiver tank I already had in my truck. I also thought it would be a good training opportunity for my friend that was helping me that night.

[thefonz1]

is the txv bulb mounted vertical or horizontal?
and is it well insulated.

If the powerhead is colder than the bulb, charge migration will occur and you will lose control of the superheat. If the bulb is mounted vertical and the the charge can migrate to the powerhead, via gravity, the valve will not control properly. this is especially true of ZP charged bulbs. The pig tail should be facing up if it is mounted vertically.

if its horizontal, the pig tail should be up also, and on the top of the pipe.

Also the quarter ton valve will be rated at "nominal" capacity, i can't recall the specs the sporlan will rate for "nominal" but it may be too small for the application. It might be rated for a quarter ton for a 0f evap, or 20f evap. Might want to check you capacity on the valve on the sporlan site.

[nchvac]

With a 270 head and an unconfirmed suction, extra subcooling---are we overcharged?

[thefonz1]

another easy thing to check is moisture blocking the valve, heat the valve body with a heat gun. if it start flooding the evap, there is moisture freezing on the txv needle.

[wannafreeze]

But what is the head pressure when it stops pulling down? What I am thinking is that at the lower head pressure, you aren't pushing liquid through the tev when you should be. In other words it seems that the liquid is laying in the line instead of being pushed through the tev. This is why you have so much subcooling.
I bet that if you were to block the condensor and raise the head, you would pull the box down to further because you would be pushing the refrigerant through the tev.

You are following it correctly. The head pressure drops slightly, like from 260-270 to 250. ( I did this so many times, I don't have one number) And the liquid line (which I made it of 1/4" new line) gets cooler.
I didn't attemt to block the c.coil because I am in a room temperature environment, it should work at that head pressure anyway. Condensor doesn't blow warm air,because there is no heat removal from inside.

[Freezeking2000]

aja2419zxa compressor.
trenton tlk160 evap.
Two door freezer.Label says 134a.Two steel door upright freezer for donuts etc.
A couple of years ago I told the owner that the freezer looks like a mismatch. At that time I was able to make it work with the refrigerant I put in.(must had been 404a). They weren't interested in conversion.It worked fine for a long time until now.
Two weeks ago when I was out of town they had to call some other guys for this freezer, they came a few times. Brought a new 404a tank. The tank was maybe 10# and left at the store after they had a fight with the store manager. No cap tube was changed they probably didn't even realized it was a mismatch. When I got there the freezer wouldn't go low enough (16F) and with the typical 404a head pressure suction was high to pull it lower. I thought it was obvious. I replaced the refrigerant. With some lower head pressure I aimed a lower evporation temperature. Couldn't get it work right. Gave them my price for replacing the cap tube with my guarantee that if it won't work I don't charge anything. While I was doing it I changed my mind and decided to convert it to txv without changing my price which is not my main concern any more.
I left the c032 cap filter drier I originaly installed for the new cap tube in the liquid line hoping that it would be alright for the 1/4 ton zp txv, which I think is not the cause of the problem I am facing now. After that filter/drier I installed a nice size (not too big, not too small, a couple of LBS ) receiver tank, made a new 1/4 line for txv.
The suction size coming out of evap is a 3/8..
I put 3 cases of water bottles inside. Over night it only pulled down to +20F. Txv was starving the evap. With about 250/23 psi pressures. Suction line was too warm, didn't even need to measure. Nothing obviously wrong as far as heaters being on, fans turning in the wrong direction, coils being dirty etc. Adding a little 404a just ends up in being pumped down. There is no shortage of it. No sight glass. To get some lower superheat at the bulb spot opened the valve, ended up opening all the way. Came back a few hours later. Colder box (10 F), with about 15 * SH at the suction line a few feet out of the evap.( outside of box ).

Decided to replace the txv again. It seems like without adjusting the stem, it's behaving the same way. Starving the coil, temperature not moving like you would see normaly in a freezer. Freezer insulation, gaskets etc. very well. Everything seems functional.
Before I put a 1/2 ton zp in there I want to ask, do you have any idea why a 1/4 ton 404a zp would starve that coil? I blew throug the coil with nitro, nothing strange there. I am just so annoyed by getting nailed by a freezer like this, I can't except it. Like I said it's not about money anymore. The coild btuh rating should not have anything to do with the type of the refrigerant, would it? And that c032 cap f/d is before the receiver tank with no apperant restriction. The heavy frost starts at the txv anyway. It just acts like it's too small to flood the coil. But why would it feed it more when I opened it up all the way? It went from 20 psi to about 35 psi when I opened it. I don't think I am rushing in my adjustment time either. I give it enough time to do something.

O well, something had to break the monotony..

PS. Maybe it needs to be externally equilized? Did I just find the answer ?


I think the suction is to high? I would think you should see 20hg. I would have changed the compressor before adding a TXV. I have heard of this being done, but personalluy have never done it. Change compressor and cap tube back to OEM specs. I would go back to 134a if thats what it was day 1.

[wannafreeze]

is the txv bulb mounted vertical or horizontal?
and is it well insulated.

If the powerhead is colder than the bulb, charge migration will occur and you will lose control of the superheat. If the bulb is mounted vertical and the the charge can migrate to the powerhead, via gravity, the valve will not control properly. this is especially true of ZP charged bulbs. The pig tail should be facing up if it is mounted vertically.

if its horizontal, the pig tail should be up also, and on the top of the pipe.

Also the quarter ton valve will be rated at "nominal" capacity, i can't recall the specs the sporlan will rate for "nominal" but it may be too small for the application. It might be rated for a quarter ton for a 0f evap, or 20f evap. Might want to check you capacity on the valve on the sporlan site.

You made some very important points. The answer may lie in them.

The power head is almost leaning against the evap coil since that's the way it fit there. There should be about a 1/4" space from the coil though since I don't like it to corrode from the touching. Never thought of the effect of the cold coil on the txv ..Bulb is horizental. The pig tail may not be the issue. I don't remember all three valves' pig-tail positioning right now.

Now to remind, there also is fan delay which causes that coil to get very cold. And I think it acts a little late but it worked everytime. I wonder if there is some heavy migration issue with the power head that confuses the valve..

[wannafreeze]

for some of you who may think there might be moisture in system: i didn't focus on that because the first valve i installed responded to adjustment. With moisture or any other blocking agent the valve should not respond.eh?

[thefonz1]

o sorry, i just re read my post, on the horizontal, the pig tail should be down towards the pipe, then the liquid has a harder time migrating.

Insulating the valve seems like a good idea. It seems like you have checked almost everything else. I would try heating the valve too, as you said the problem happens right around the freezing point, might as well check for moisture before you insulate it.

Good luck!

[wannafreeze]

o sorry, i just re read my post, on the horizontal, the pig tail should be down towards the pipe, then the liquid has a harder time migrating.

Insulating the valve seems like a good idea. It seems like you have checked almost everything else. I would try heating the valve too, as you said the problem happens right around the freezing point, might as well check for moisture before you insulate it.

Good luck!

even though I said just before you posted this one, why I didn't suspect moisture, it really seems like just what moisture would do around freezing temperature. But the valve responds to adjustment. ?

[VTP99]

If box temp got to 10*with a 10*TD would put your coil temp @ 0*. If the power head is touching coil (BINGO) if any air gap your still looking. If ice in TXV use heat gun as stated. Bulb position 3-4 o'clock or 8-9 .

[stonewall]

All expansion valves with MOP have a very small
charge in the bulb.
This means that the valve or the element must be
located warmer than the bulb. If it is not, charge
can migrate from the bulb to the element and
prevent the expansion valve from functioning.


The valve opens slowly as bulb temperature rises
and closes quickly as bulb temperature fails.

try it with out the mop power head.:anyone:

[Joe Harper]

Are you using the same powerhead on all of these valves?
If you were to walk up on this system with no history on it what would your conclusion be?

[wannafreeze]

try it with out the mop power head.:anyone:


Than without the mop ph. would I need to install a cpr valve?

[wannafreeze]

Are you using the same powerhead on all of these valves?
If you were to walk up on this system with no history on it what would your conclusion be?

all three valves I tried were zp.
my conclusion in that case would be moisture or bad txv. and after eliminating the two I would probably lean towards a bad pump.
depending on what can develop with the customer I may take the txv somewhere else and replace the filter/drier again. I had fired this customer in 2009. With some people intervening I started carefully servicing them again. I already told them that, without a proof, I think replacing the compressor will solve the problem and I need the cash in my hand before doing it. They will answer me tomorrow. I don't know what the reaction is going to be like. I want to take care of this to have a closure.I can't let a freezer defeat me at this stage and live with that memory.

[VTP99]

What if you change the compressor and end up with same problem ? :eek:

[ETC1]

What is the manufacturers refrigerant listing on that model compressor. What is the box manufacturers actual refrigerant spec. Your on a computer don't reinvent the wheel ,locate phone number for tech service of company. Labels can be wrong.

[wannafreeze]

What if you change the compressor and end up with same problem ? :eek:

Before doing it I will take the txv on a warmer spot ( outside of evap), replace the drier, I will make sure there is no moisture and if it still won't work I will install a cap tube. I also didn't give them guarantee with the compressor issue. I told them I am not able to test it, and they will have to take the chance, I won't.(meaning I won't buy it from my pocket). It's not a customer that I respect a lot. I have been trying to fix this at my expense so far. They are not paying a dime until it's fixed. But I don't offer the same deal with compressor replacement.
I want to take the txv out of evap before I do anything else though.

Hopefuly nothing develops to stop me from keep trying. I don't mind spending a couple of hundred $ if it's going to make me a better, more seasoned refer man.

[wannafreeze]

What is the manufacturers refrigerant listing on that model compressor.
that's been obvious: aja2419zxa is a 404a compressor.

What is the box manufacturers actual refrigerant spec. Your on a computer don't reinvent the wheel ,locate phone number for tech service of company. Labels can be wrong.
can you find me 'leader's phone # ?

What the manufacturer did is not relevant to our discussion. You should be able to make it work with a matching C/U , evap coil , metering device and refrigerant.

[VTP99]

Oh ya I've been down that road where your stuck between a rock and a hard spot. Hard to charge for all your time and the problem is not fixed. Makes one want to change careers. But this profession is a sickness because we never walk because we can't live with defeat. Would rather lose money then give up. Trust me you will win the battle but at what cost ? You know and i know their is answer to your problem that only time will fix.

[VTP99]

Wanna phone # for Leader ?
(718) 399-2866

[icemeister]

is the txv bulb mounted vertical or horizontal?
and is it well insulated.

If the powerhead is colder than the bulb, charge migration will occur and you will lose control of the superheat. If the bulb is mounted vertical and the the charge can migrate to the powerhead, via gravity, the valve will not control properly. this is especially true of ZP charged bulbs. The pig tail should be facing up if it is mounted vertically.

if its horizontal, the pig tail should be up also, and on the top of the pipe.

Also the quarter ton valve will be rated at "nominal" capacity, i can't recall the specs the sporlan will rate for "nominal" but it may be too small for the application. It might be rated for a quarter ton for a 0f evap, or 20f evap. Might want to check you capacity on the valve on the sporlan site.

Charge migration...You may have identified the root of the problem. (Why didn't I think of that? :( )

The ZP pressure limiting element has a gas charge which is, as you say, susceptible to charge migration if the bulb temperature is warmer than the thermostatic element. The standard Z charge is a liquid cross charge which prevents migration.

Thinking back to the TEV retrofits I have done in the past, all were on systems with CPR valves already in place (like the True GDM-F series) and so I installed a Z charge TEV, never having a problem. The migration issue make a lot of sense now. The system pulls down well initially but after a while the element cools down enough to cause migration and it all goes to crap.

It quite likely all that is needed at this point is to change out the thermostatic element and add a CPR valve. Good work Fonz. :)

As for the valve sizing, the nominal capacity for a given valve, refrigerant and evaporator temperature is based on 100ºF liquid temperature and 100 psi pressure drop across the valve. To arrive at an actual capacity you have to apply correction factors which reflect expected conditions. In this case
the liquid temperature is probably OK at 100ºF but the pressure drop is about 235 psi (270-15). This would call for a correction factor of nearly 1.5.

The FS-1/4-ZP valve has a nominal capacity of .27 tons at -20ºF SST on R404A so the actual capacity is more like .40 tons. This why I stated earlier that a 1/8 ton valve would be a better choice.

[frozensolid]

I did not read the whole thread so if I am duplicating here sorry. But if you have no distributor I expect there is no orifice to see that the coil gets fed evenly (very important on low temps). Seeing that liquid flows down, is it possible that you are flooding the bottom half of the coil? Causing the valve to close as it senses a cold flooded suction line?

Is the bottom half of the coil frosting more than the top?

[VTP99]

Why would TXV be warmer then the bulb ? TXV in box amb. 10*. Bulb on Suction line @ coil temp. 0*:anyone:

[wannafreeze]

Is the bottom half of the coil frosting more than the top?

yes

[wannafreeze]

Charge migration...You may have identified the root of the problem. (Why didn't I think of that? :( )

The ZP pressure limiting element has a gas charge which is, as you say, susceptible to charge migration if the bulb temperature is warmer than the thermostatic element. The standard Z charge is a liquid cross charge which prevents migration.

Thinking back to the TEV retrofits I have done in the past, all were on systems with CPR valves already in place (like the True GDM-F series) and so I installed a Z charge TEV, never having a problem. The migration issue make a lot of sense now. The system pulls down well initially but after a while the element cools down enough to cause migration and it all goes to crap.

It quite likely all that is needed at this point is to change out the thermostatic element and add a CPR valve. Good work Fonz. :)

As for the valve sizing, the nominal capacity for a given valve, refrigerant and evaporator temperature is based on 100ºF liquid temperature and 100 psi pressure drop across the valve. To arrive at an actual capacity you have to apply correction factors which reflect expected conditions. In this case
the liquid temperature is probably OK at 100ºF but the pressure drop is about 235 psi (270-15). This would call for a correction factor of nearly 1.5.

The FS-1/4-ZP valve has a nominal capacity of .27 tons at -20ºF SST on R404A so the actual capacity is more like .40 tons. This why I stated earlier that a 1/8 ton valve would be a better choice.

the elemenmt sits close to the coil.if i pipe it outside the evap housing then it should be okey?

[frozensolid]

I am not sure I understand the question VT?

The TXV has warm liquid running through it, this should keep it warm and comfy. If its is icing it is restricting, only the outlet should ice in my experience.

[frozensolid]

yes


This is a problem, have you said this previously in the thread?

[wannafreeze]

I am not sure I understand the question VT?

The TXV has warm liquid running through it, this should keep it warm and comfy. If its is icing it is restricting, only the outlet should ice in my experience.

outlet is icing only, correct. more like from half the txv, just like a starving one.
the reason i want to agree wiht migration is because the dome is almost leaning against the coil. and fans kick on when suction is too cold like
-3*F, I made sure the sensor is nicely srewed on to the copper plate. but it still works a little late too.

[VTP99]

I am not sure I understand the question VT?

The TXV has warm liquid running through it, this should keep it warm and comfy. If its is icing it is restricting, only the outlet should ice in my experience.

Back up a few post. Their talking about moving the valve. I see no reason unless power head is up on the coil.

[lane]

Email pics of everything to a few of the guys helping you... just a suggestion.

Lane

[frozensolid]

It would seem to me if you starve the coil the entire coil should starve. You need to address why the top of coil is not feeding. Not having and orifice to disperse the refrigerant is one possible answer.

What ever is causing that condition must be addressed.

[icemeister]

I did not read the whole thread so if I am duplicating here sorry. But if you have no distributor I expect there is no orifice to see that the coil gets fed evenly (very important on low temps). Seeing that liquid flows down, is it possible that you are flooding the bottom half of the coil? Causing the valve to close as it senses a cold flooded suction line?

Is the bottom half of the coil frosting more than the top?

I don't think this an issue here because these little evaporator coils aren't multi-circuited. They're a single pass so no distributor is needed. The frost on the bottom rows is probably happening because they're the first rows to be fed. The upper rows are basically just starved, and so no frost.

[frozensolid]

That would make sense, if it feeds from the bottom.

[icemeister]

the elemenmt sits close to the coil.if i pipe it outside the evap housing then it should be okey?

I'm not sold that moving the valve would solve the problem. I'm thinking the valve isn't being cooled by the surrounds as much as it is by the super cold liquid leaving it. You probably have -20ºF liquid leaving and the bulb is likely close to the box temperature of +10ºF or so. All it would take is to have one small portion of the element to be below +10ºF for charge migration to occur.

It may be a bit of a stretch, but that's what I now believe is happening.

[VTP99]

Supposedly it worked with a cap tube. Never did get a model # of unit.
Last two door i work on was a Victory w/ two cap tubes feeding top.

[tipsrfine]

That's why i can't even offer a new evaporator. Because I can't be sure at this point.
The old cap tube connection, I cut that out. There was a flare nut already on the tubing. Also I blew the coil out with nitrogen from the compressor side. No apperant problem there. Adding a pressure tap won't be that easy. Since this is not a WIB it would not be easy to see the operating pressures. But I could probably braze a 3/16 tube and run it outside the freezer to measure that pressure. At this point I was giving up on this and after taking my receiver tank and txv I was going to install the cap tube I already cut for this..
That suction line performed fine, but with a cap tube..
I might muster more energy by saturday and decide to experiment further.
I just hope it's not something stupid I missed and somebody else comes and takes care of it.

The refrigerant is definetaly not short. And it's at the flare inlet connection.( cracked the flare )

Is it posible there may be a restriction immediately before the txv right at the flare connection (that was already there) that is in fact starving the txv? Enough of a restriction to starve it without actually creating noticable frost at the inlet of the txv due to it being so close? Maybe somebody shoved a little rolled up screen down it to protect the cap tube and now it's partially blocked. This thread is long enough now to consider the crazy ideas.

[VTP99]

The refrigerant is definetaly not short. And it's at the flare inlet connection.( cracked the flare )

Is it posible there may be a restriction immediately before the txv right at the flare connection (that was already there) that is in fact starving the txv? Enough of a restriction to starve it without actually creating noticable frost at the inlet of the txv due to it being so close? Maybe somebody shoved a little rolled up screen down it to protect the cap tube and now it's partially blocked. This thread is long enough now to consider the crazy ideas.

He removed that and put a new liquid line in up to his new TXV. But interesting idea. Wonder why there was a flare to begin with ? Cap tube should have gone right into evaporator. Also i don't think cracking the fitting con statues a full column of liquid.

[tipsrfine]

He removed that and put a new liquid line in up to his new TXV. But interesting idea. Wonder why there was a flare to begin with ? Cap tube should have gone right into evaporator. Also i don't think cracking the fitting con statues a full column of liquid.

I know he removed the the old cap tube, but I'm not seeing where he said he removed the flare nut. The way he mentioned it already being there impies to me he left it on.

[icemeister]

He removed that and put a new liquid line in up to his new TXV. But interesting idea. Wonder why there was a flare to begin with ? Cap tube should have gone right into evaporator...

The Trenton TLK-160 comes from the factory with a 1/2" flare inlet connection:
http://www.trentonrefrigeration.com/Products/Evaporators/tlk_sb.pdf

[wannafreeze]

I'll try to anwser some of your's questions.
Yes there was a flare not hanging on the evap outlet before I removed the original cap tube.
I called leader. I can't understand chinese but what I got out of it is, today they manufacture those fr54 freezers with 404a. She can't tell anything about how it was made 8 years ago. And the insulation is styrofoam.

Today I went there for the last time.

Box was at 20*F, pressures 250/17 psi. Coil was starved.

I decided to go back with a cap tube. 29" of supco #2. Removed the receiver tank. When I first charged the system I went up to 300 psi/30-35 psi pressures. When evorator superheat got down to 2* box stopped cooling any further, stayed around 20*F. I removed some refrigerant to drop evoporation temperature. Final pressures 240/20 psi, box 25*F, evap outlet 15*F. Discharge temp 158*F. Liquid line 95*.
So I had high superheat with good subcooling. But the low side pressure should start around 23psi, so as the box gets colder it should be able to run at a very low evoratoion temperature. So i wouldn't leave it overcharged just to get the coil cold real fast.
I do believe it has something to do with the wall insulation. It's acting just like when a cooler takes in warm air. The walls are very loose. I wonder that styrofoam they used crumbled down with the melt down. I convinced them to leave it running until sunday. Maybe inside the walls should freeze up. As far as the txv, I have no idea why it kept starving the coil. Unfortunately i took the whole freezer's amp draw from the timer, not realizing, so the total freezer amp draw is 7.8 amp. Which may still give an idea of the compressor amp draw. It's below the fla ..

[VTP99]

I know he removed the the old cap tube, but I'm not seeing where he said he removed the flare nut. The way he mentioned it already being there impies to me he left it on.

He said he left it on. But he would've had to cut out the old cap tube and install the new 1/4'' liquid line. He should have seen any restriction. Also a screen would not protect the cap tube at the end.

Icemeister,
Trenton's link gives me the impression this coil was design for a TXV. Also it shows 1/2'' outlet and he's using 3/8"" but probably no biggie there.

Wanna,
You meant evaporator inlet not outlet right ?

[icemeister]

Icemeister,
Trenton's link gives me the impression this coil was design for a TXV.


Yes they are designed for use with an expansion valve, but there's no reason you can't use a capillary tube. I done it a number of times when replacing an evap in a old beater. It works just fine.

I prefer them with a TEV though.

[VTP99]

Yes they are designed for use with an expansion valve, but there's no reason you can't use a capillary tube. I done it a number of times when replacing an evap in a old beater. It works just fine.

I prefer them with a TEV though.

I understand there should be no problem with a cap tube meter but i have to wonder why a manufacture would spec a coil built for a TXV/TEV and then use a cap tube.

[icemeister]

I understand there should be no problem with a cap tube meter but i have to wonder why a manufacture would spec a coil built for a TXV/TEV and then use a cap tube.

http://leaderrefrigerator.com/

This is a small, 18 year old manufacturer in Brooklyn, NY with 20 employees...not exactly in True's league where they can build their own coils and such. I'm sure it's just a matter of being able to buy ready-made components like evaps and condensing units at OEM prices allows them to build stuff without all that extra overhead.

I noticed looking at their webiste info that the FR-48 freezer has a 1/2 hp unit whereas their FR-54 box (the one in this thread) now has a 3/4 hp. Hmmm?

[wannafreeze]

UPDATE : On post #87 I updated the situation. I think you guys missed to see it..

[wannafreeze]

POST #87:

I'll try to anwser some of your's questions.
Yes there was a flare not hanging on the evap outlet(Correction: inlet) before I removed the original cap tube.
I called leader. I can't understand chinese but what I got out of it is, today they manufacture those fr54 freezers with 404a. She can't tell anything about how it was made 8 years ago. And the insulation is styrofoam.

Today I went there for the last time.

Box was at 20*F, pressures 250/17 psi. Coil was starved.

I decided to go back with a cap tube. 29" of supco #2. Removed the receiver tank. When I first charged the system I went up to 300 psi/30-35 psi pressures. When evorator superheat got down to 2* box stopped cooling any further, stayed around 20*F. I removed some refrigerant to drop evoporation temperature. Final pressures 240/20 psi, box 25*F, evap outlet 15*F. Discharge temp 158*F. Liquid line 95*.
So I had high superheat with good subcooling. But the low side pressure should start around 23psi, so as the box gets colder it should be able to run at a very low evoratoion temperature. So i wouldn't leave it overcharged just to get the coil cold real fast.
I do believe it has something to do with the wall insulation. It's acting just like when a cooler takes in warm air. The walls are very loose. I wonder that styrofoam they used crumbled down with the melt down. I convinced them to leave it running until sunday. Maybe inside the walls should freeze up. As far as the txv, I have no idea why it kept starving the coil. Unfortunately i took the whole freezer's amp draw from the timer, not realizing, so the total freezer amp draw is 7.8 amp. Which may still give an idea of the compressor amp draw. It's below the fla ..

[icemeister]

UPDATE : On post #87 I updated the situation. I think you guys missed to see it..

Yeah....I saw that. I'm just bummed out now because we'll never know what the problem was with the TEV. :)

[wannafreeze]

Yeah....I saw that. I'm just bummed out now because we'll never know what the problem was with the TEV. :)

Ice, the person that gave me some info at leader was not willing to talk about the old version of the fr54. She was like "I can't give you any information about the old ones." with a nervous voice.
My guess is the insulation gives up in time and that correctly sized compressor can't handle the new situation and they tried the 3/4 HP compressor and that's why they went up. I think there is no insulation left inside the walls.
How many times I poked the walls to feel what's inside and went inside the box with the doors closed to see why it's not pulling below 25*F...

And when I left I told them the walls inside need to freeze up, if they do the freezer will work. I can't do anything else..

I am still willing to speculate or listen to speculations about the txvs..

[VTP99]

http://leaderrefrigerator.com/

This is a small, 18 year old manufacturer in Brooklyn, NY with 20 employees...not exactly in True's league where they can build their own coils and such. I'm sure it's just a matter of being able to buy ready-made components like evaps and condensing units at OEM prices allows them to build stuff without all that extra overhead.

I noticed looking at their webiste info that the FR-48 freezer has a 1/2 hp unit whereas their FR-54 box (the one in this thread) now has a 3/4 hp. Hmmm?

Icemeister,
This is the site i got the phone # for post # 67 after he asked in post # 65. At that time i did not look at the site just acquired phone #. I see now after going back to leaders site the horsepower increases to 3/4 as noted but if you look at there NFR-54 the N.F.S. model it is still 1/2 hp. :eek2: Looks like the only difference between the two is all stainless & rounded corners at wall and base. Like N.F.S. sinks.
The jury is still out on what is wrong. What confuses me are the pressures. Started @ 300psi=115*30/35=0*average. Box temp @ 20*and 2*superheat. With a 20* box temp and a 10*TD coil would be about 10* but pressures are showing 0* and with a 2* superheat how could the coil be starved ? Today pressures were @ 250psi=105*17= -20* box temp @ 20* :eek2: