randell reach in driving me crazy

[swinginutters]

i'm currentley wroking on a randell 2 door reach in prep top swith a cold rail no model # its' "custom". it runs 404. i noticed the box would be 50 degrees sometimes , and sometimes run fine at 38 all day. figured out when the cold rail on top gets turned on at night when they load it, the box goes warm. 50-55 degrees. and the rail barley sweats, doesn't have that nice frost pattern. pressures are 55/275 with no rail and 85/260 with rail on. then with rail on, after about 10 minutes the compressor gets too hot, trips on overload, turn the rail off, cool down the compressor it's happy the box pulls back down below 40. My manager suggesting changing out the TXV on the rail, and the compressor due to it rattleing a bit. sounded good to me, they didn't give me a factory txv, they gave me something that "should work" got it all in. and it's pretty much doing the same thing box runs great by it's self 40 degrees, 60/285, turn the rail on box gets warm and the rail barley sweats. and my pressures are 100/265 which is obiously too high. and the box goes warm 55 degrees. comp amps are 0k but maxed out at 7. I can't adjust this txv back any it's internally equalized with no stem. I thought maybee a CPR but it diodnt have one originally. Or I've heard of some Txv's have a CPR built in? I wish they would have called randell and got ,me the same TXV. any thoughts would be appreciated

[beachtech]

the condenser coil is clean?

you cleaned it?

is it a combo reach in and cold rail. LL selenoid valve. changed one a few weeks ago for one of my accounts. maybe sticking open or closed....

TXV "should work" did you check to see if it is the right one? BTU's from compressor will help alot in txv selection.

[swinginutters]

condensor coil is clean, both LL siliniods open and close when called.

[beachtech]

the doors are staying closed, gasskets are in god condition?

something simple maybe?

although i am sure you checked all this, and it's hard to see if employees that are using the box are closing the doors everytime, when you not there to pull door guard duty :D

sounds like the txv that should work might be too big. why won't they get you OEM one? was it a sporlan txv. i would call randell and ask them what size txv should be on there, and compare to what you put in. there are two txv's for each section, right? i worked on one a few weeks back, the LL seleniod wouldn't close for the cold rail, and the cold rail turned into a big block of ice after a few months lol :)

[Bill Bednarick]

The oem R404 Randell TXV is an Emerson/Alco. I was told by the local supply house that is is an internally equalized 1/4 ton valve. We opted to order an OEM but have not put it in yet. We were seeing low suction and discharge pressures after weighing in the 16 oz. charge per the manufacturers tag. We were seeing about 20 on the low side and 175 on the high.

[beachtech]

The oem R404 Randell TXV is an Emerson/Alco. I was told by the local supply house that is is an internally equalized 1/4 ton valve. We opted to order an OEM but have not put it in yet. We were seeing low suction and discharge pressures after weighing in the 16 oz. charge per the manufacturers tag. We were seeing about 20 on the low side and 175 on the high.

are you the same guy :confused:

--------------------------------------------------------------------------------
swinginutters
i'm currentley wroking on a randell 2 door reach in prep top swith a cold rail no model # its' "custom". it runs 404. i noticed the box would be 50 degrees sometimes , and sometimes run fine at 38 all day. figured out when the cold rail on top gets turned on at night when they load it, the box goes warm. 50-55 degrees. and the rail barley sweats, doesn't have that nice frost pattern. pressures are 55/275 with no rail and 85/260 with rail on. then with rail on, after about 10 minutes the compressor gets too hot, trips on overload, turn the rail off, cool down the compressor it's happy the box pulls back down below 40. My manager suggesting changing out the TXV on the rail, and the compressor due to it rattleing a bit. sounded good to me, they didn't give me a factory txv, they gave me something that "should work" got it all in. and it's pretty much doing the same thing box runs great by it's self 40 degrees, 60/285, turn the rail on box gets warm and the rail barley sweats. and my pressures are 100/265 which is obiously too high. and the box goes warm 55 degrees. comp amps are 0k but maxed out at 7. I can't adjust this txv back any it's internally equalized with no stem. I thought maybee a CPR but it diodnt have one originally. Or I've heard of some Txv's have a CPR built in? I wish they would have called randell and got ,me the same TXV. any thoughts would be appreciated

[Bill Bednarick]

are you the same guy :confused:

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Nope just trying to help swinginutters with what I've seen on a similar piece of Randell equipment.

Sorry for any confusion.

[mud]

Did you try running just the rail? If so what were the results.

[ice-LI]

if i am correct dosent 404a require poe oil to operate? if so when you put in the new txv did you change the dryer. poe absorbes the slightest amount of moisture and can be stuck in the txv causing very high head pressures. might want to reclaim the refrigerant, change the dryer and weigh in the charge as per the mfgr. and having the oem txv couldent hurt.

[Bill Bednarick]

Swinginutters,

Any updates on this?
BTW You can get the oem Randell TXVs and other Randell parts from http://www.caseparts.com.

[nchvac]

Another point--weigh it in if possible.

[beachtech]

Another point--weigh it in if possible.

on these small appliances, weigh in all the time ;)

[leakcheck]

you did get the Txv bulb strapped down tight to the correct line ? A warmer line will of course open that Txv right up. And do you have the model of TXV you put in ? We could then tell you all the specifics of it.

[rselby]

Overcharged possibly? I'd weigh in 1/2 the charge fire it off and watch the pressures as I slowly added gas from that point.
Has this compressor been changed out before?
You've received some good information so far, Randall Preps can be a real B----.

Good luck!

[coolingitrite]

i ran into this before one time the reps told me the spec plate charge info was wrong the second one i found that the compressor was changed out but the wrong compressor was intalled. i think it was an r22 compressor. i ould also check to make sure that txv bulb has good contact.

never had much luck with their reps either.

[swinginutters]

yes, i changed the dryer used new 404, the TXV my boss gave me wasn't OEM (I wasn't a fan of that and I wouldn't even be writing this if I would have gotten the right one)., when i put it in it was over feeding getting high suction around 100, bulb was tight the adjustment was internal so high had to pull it apart few more times till i got the suction down to 50. It's running good now, and the lesson is don't just use a txv that "should work". get the right one. what was supposed to be a half a day job turned into about 14 hours.

[nchvac]

yes, i changed the dryer used new 404, the TXV my boss gave me wasn't OEM (I wasn't a fan of that and I wouldn't even be writing this if I would have gotten the right one)., when i put it in it was over feeding getting high suction around 100, bulb was tight the adjustment was internal so high had to pull it apart few more times till i got the suction down to 50. It's running good now, and the lesson is don't just use a txv that "should work". get the right one. what was supposed to be a half a day job turned into about 14 hours.

What do you mean by saying that you "had to pull it apart a few more times" to get it down to 50?

[icehouse]

Contractor
Service Tips


Tip Card21
Quick Facts - Internal or External
Equalized TXV

Q:
What is the difference between an ‘internally’
equalized and ‘externally’ equalized TXV?
An internally equalized TXV uses evaporator inlet pressure
to create the ‘closing’ force on the valve. An externally
equalized valve uses the evaporator outlet pressure’
thereby compensating for any pressure drop through the
evaporator.

If an internally equalized valve is used in a system with a
large pressure drop through the evaporator, the pressure
below the diaphragm will be higher, causing the valve to go
in a more ‘closed’ position and resulting in a superheat
higher than desired (starving).

Q:
When should I use an externally equalized TXV?
1. On any large system, generally over 1 ton capacity
2. On any system utilizing a distributor
Note: For field replacement you can always replace an
internally equalized valve with an externally equalized type;
however, you should never replace an externally equalized
valve with an internal type.

Q:
If I need to replace an internally equalized valve
and all that is available is an externally
equalized type, can I simply ‘cap’ the equalizer
fitting?

No, the equalizer must be connected to the suction line
near the thermal bulb. Capping the equalizer line will
prevent the valve from operating properly.

Q:
Will an externally equalized TXV allow system
pressures to ‘equalize’ during off cycles?
No, an externally equalized valve will NOT allow system
high and low sides to ‘equalize’ during the off cycle. The
only way this can be accomplished is through the use of
a ‘bleed’ type TXV.

Q:
Where should the external equalizer be
installed?
The external equalizer line should be installed on top of
the suction line before any traps and located within 6
inches of the sensing bulb position. If this is not possible,
and a different location is required, it must first be
confirmed that the pressure at the desired location is
identical to the pressure at the bulb.

Q:
What happens if the equalizer tube becomes
‘kinked?’
If the equalizer line becomes ‘kinked’ the pressure
sensed at the underside of the diaphragm will no longer
correspond to the evaporator outlet pressure and the
valve will not be able to operate as intended.

Q:
I have seen some equalizer tubes ‘frosted.’ Is
that normal?
Frost on the equalizer line is an indication that the
packing seal has failed, allowing higher pressure
refrigerant to leak past and expand into the equalizer
line. Depending on the valve type, either the cage
assembly or the entire valve should be replaced.

Form No. 2005FC-257 Issued 1/06
Emerson Climate Technologies logo is a trademark of Emerson Electric Co.
© 2006 Emerson Climate Technologies. Printed in the USA.




[rselby]

This is great back to the basics information, FUBAR= Frequently Unused But Always Reliable. Thank you for putting that up icehouse.;)

[icehouse]

It is why I became a member of the "Educational Committee". I am a firm believer of the more you know the easier your job is to complete. This results in three very happy people.
1.The customer 2. Your employer 3.Yourself, as there is personal satisfaction to a job well done. :)

[QTEMP]

You have a bad TXV on the rail system......buy a Danfoss TXV with the correct orfice in it. 85 is way too high......should fix the problem and watch your charge with these things.....I have found name plates can be wrong....

[icehouse]

I would stick with Sporlan. Danfoss has way to many problems.

[QTEMP]

I would stick with Sporlan. Danfoss has way to many problems.

Not from what I've seen...I used to be hooked on Sporlan until their power heads rusted prematurely....I think we have had one or two bad Danfoss TXV's a year and we have changed quite a few....to each his own..

[icehouse]

Not from what I've seen...I used to be hooked on Sporlan until their power heads rusted prematurely....I think we have had one or two bad Danfoss TXV's a year and we have changed quite a few....to each his own..
Do a forum search and you will see that I am not alone on this.

[QTEMP]

Do a forum search and you will see that I am not alone on this.

I will do that...thank you

[nchvac]

It is why I became a member of the "Educational Committee". I am a firm believer of the more you know the easier your job is to complete. This results in three very happy people.
1.The customer 2. Your employer 3.Yourself, as there is personal satisfaction to a job well done. :)

Can you elaborate a little on what the education committee does and what areas it posts under?

[nebtechmaster]

You never mentioned anything about superheat. Did you check this? Try running the rail with out the box and check the superheat. This is the only proper way to test and set a txv. Also check condenser coil all the way through sometimes they look clean on the surface but are really dirty inside (especially in a restaurant) Adding the load of a warm rail could be a problem. Another thought is the refrigerant. An under charge on a txv system will cause high back pressure and slightly low head pressure. Until the system has enough refrigerant the txv can't meter down.

GOOD LUCK!

[icehouse]

Can you elaborate a little on what the education committee does and what areas it posts under?Educational Forums
comittee members are dedicated to helping all to become the best they can be. This is done by constant research and communication with industry greats.
Headed by our own "Super Tech" Icemeister.

[Bill Bednarick]

You never mentioned anything about superheat. Did you check this? Try running the rail with out the box and check the superheat. This is the only proper way to test and set a txv. Also check condenser coil all the way through sometimes they look clean on the surface but are really dirty inside (especially in a restaurant) Adding the load of a warm rail could be a problem. Another thought is the refrigerant. An under charge on a txv system will cause high back pressure and slightly low head pressure. Until the system has enough refrigerant the txv can't meter down.

GOOD LUCK!

This is a good point but my question is would it be better to use a medium temp basic rule of thumb for super heat or use a factory recommended range?
You would think that 20 degrees at the compressor would be OK right? Based on the Copeland recommended info. The Randell units I have seen are Tecumseh compressors but it shouldn't make the Copeland info null and void. Or would you go 10 to 15 coming out of the rail like it was a medium temp evaporator?

[icehouse]

Superheat at the evaporator for "Medium Temperature" is 8*-10* FWhy not an EPR valve for the rail ?

[Bill Bednarick]

Superheat at the evaporator for "Medium Temperature" is 8*-10* FWhy not an EPR valve for the rail ?

Dunno on the epr, they don't come from Randell with one and as designed evidently don't need one. That being said the last one I replaced the txv on (for the rail the reach in uses a cap tube) was 21 degrees of superheat at the compressor and the pressures were about 55 on the low and 275 on the high with the unit not yet down to temp.

I guess I thought the evaporator superheat rule on medium temp was 10 to 15. But after looking again at the rule of thumb stuff I have I see it's 5 to 8 for low 8 to 10 on medium and 10 to 15 on high temp stuff.

I personally have really considered going to Randell's in house school as it's not far from me and I've seen several this year that needed service and I'd rather know than guess.

[icehouse]

Well if it needs one to maintain a constant temperarure, why not and avoid problems in the future.

[Bill Bednarick]

Well if it needs one to maintain a constant temperarure, why not and avoid problems in the future.

As I am not the original poster so I cannot comment on his unit.
I've worked on a couple this year and they both worked as the customer required (things in the rail and the reach in part temped at under 40) after the repairs but I am always looking for more info on everything I work on.

Mostly I'm trying to get my post count up with relevant posts so I can get into the educational areas. And until then read as much as I can and learn as much as I can in the forums that are open to me.:D

[icehouse]

Obviously the original poster has issues with the rail maintaining temperature.He also is a little confused about expansion valves, but by posting he is looking for help.I do not know everything and I learn everyday by coming here as well as reading manufacturers material and the vast textbooks available.We have some of the best in the industry here, and I take very much pride in being associated with them as they are a wealth of knowledge.