A little guidiance please?

Harvey Ramer

Today I was doing PM on a fairly large cooler box. It has 3 condensers and 5 evaporators. 2 of the condensers and 2 of the evaporators are 1for1. The 3rd condenser has 3 evaporators piped in parallel. Each of these 3 evaps have their own txv.



The unit in question is the one with the single condenser and 3 evap coils. Simply stated, the evap temp is to high and when you pull the box down to the low 30's, it becomes ineffective. So I boldly set forth to readjust the txv's and lower the evap temp. I quickly realized I would have to come up with a unique solution to adjust them proportionately. What I ended up doing is measuring the temp of the line on the outlet of the TXV. I used this as a guide for the adjustments. I got the temp lowered about 7° and decided to let it ride for right now. Super heat on each evap coil right around 10-12°.



Before I venture to much deeper into this, I'd like to know what I'm doing right or wrong. What is the best approach to this situation?



Harvey 

Techman

Just a little

What product ? What %RH? What temp?What ambient around WIR?What controls all three stages of cooling?What application?What was evap temp/press?What was ambient @cond unit?What was cond temp?SuperHeat is SH!10* -8*- 12*!!!.What was lo/hi side pressurers.? The 1 cond x 3evap should be 1st stage of cooling ,I think.What Freon?What fun!What usage?What a PITA!

Harvey Ramer

What.....?

Ha ha :-)

Good evening Terry.



A little history first. The whole thing is a hodge podge. The box came from Ebay. It's probably about a 30 x 40 by 14' tall box. The compressors and evaporators were gathered up here and there. Nothing is designed. They started with one unit and when that didn't do it they just added more. They also have a second box that is slightly smaller. They have gone through compressors like there's no tomorrow. As soon as I get my Checkmate kit, I will be checking all of the compressors' oil. I have just recently inherited the task of maintaining this depressing array.



The box I'm on now, with the 3 compressors is primarily used for apples and peaches. That is a little bit of a quandary because they want to keep the apples around 33° and the peaches closer to 50°. All three compressors are controlled with one thermostat, via liquid line solenoids. There are no different stages.



The 1-3 unit I was playing with had a 35° evap temp (404A). I brought it down to 27°. The other 2 evaps are floating around in the 15° - 20° range (R22). I want to bring these up to a couple clicks above 20°. The compressors on these 2 units are designed for a 20° to 50° temp. High side pressures were floating around 105 to 110. Outdoor ambient around 75. Forgive my vagueness, I am just going by memory. Subcooling measured between the condenser and the receiver was about 6-8°. Then it got dark.



Am I completely missing the buss by trying to adjust the TXVs?



Harvey

icesailor

Guessing:

Let me guess.



The owner is a Yankee Farmer. Everything on the property is recycled or used when first installed.

You get to fis used and obsolete equipment installed by the owner who has just enough knowledge to solder. Or a friend who is slightly smarter.

Techman

Just a little

WOW!! What a nice job! They have two distinct products,two distinct RH% requirements and two distinct temp requirements.Can they hodge podge a divider wall inbetween what we in the "R" trade  call a "wet box" and a "dry box". What other produce do they have or plan to have?  How long are the products to be kept for? Weeks?. What is actual box temp? Are you sure you want to learn REFRIGERATION? LOL my friend! What are the compressor make& MN#, in which mn# cond unit;What Freon? What evap mfrg, MN#, how many fins per inch? I love picturers.How dirty are the evap/cond coils?Need EACH unit running P/T's w/ ambients.What is evap return air temp? On the 1-3system w/ the high EvapTemp that would be closer to normal for just the peaches. But if you are looking for a lower box temp ONLY, try disconnecting the middle evap LiquidLine Solenoid Valve. The lower the box temp the lower the box RH%. KindaSorta, they bring in 1000lbs of peaches and a week later they have 925lbs of peaches left due to the refrig system removing too much moisture. Leave the SuperHeat alone if the SH is 8-10* . The TXV or "SuperHeat maintaining device" will try to keep that 8-10* of SH even if the WIR( Walk-in-refrig) box temp  is 50* or 35* or in a 25*WIF(freezer). I'm assuming the TXV's are "externally equalized" The SH is measured by comparing the Suction Press/Temp vs the actual SL temp at the TXV thermal bulb, not TXV outlet to thermal bulb temp. This is due to the pressure drop thru the evap coil , which means, the press drop causes a temp drop, so, that "false" temp drop offsets the TXV SH. That's why the TXV is of the "external equalized type" .  What is the SH at the Suction Line going into the compressor? What is the Discharge Line temp 6"away from the comp? Heaven forbid , are there SightGlass/MoistureIndicators and if yes, what color are they.What size LL does each system have? What size LLFD is in them now? I would be thinking about a "Shell and Core" Suction line FD if there is ANY acid detected. Both SLFD and LLFD should be of the "HH" type,thats for neutralizing Hydrochloric and Hydofluric acids and possibly Oleyic acid. Got all that? I'll be contacting you in a hour or so, to find out. LOL!

Gee Harvey, you piqued my interest! Good old R.S.E.S. has some nice SAM ( ServiceApplicationManuals) on produce, makes for a nice read on a stormy nite!

icesailor

Knowing:

WOW Techman, You and Harvey probably have forgotten more than the old Yankee farmer or his soldering friend will ever know about refrigeration. They know just enough to make it cold. These farmers are the worst kind of DIY'ers. They know what they want, what they need, but don't know how to do it. They call you when all else has failed and their bottom line is boing down. Its a great training ground. No one lese would try to do what they do. So you get to try to correct things that are really uncorrectable. But you try. And learn how to really "McGyver" things.



There's no such thing as a good deal in used farm equipment. Its already worn out well beyond it's life expectancy.

Harvey Ramer

Ice

Techman is the Pro here. I'm just trying to tag along ;-)



Harvey

Harvey Ramer

I got work to do.

Next time I'm out there, I'll profile the whole system. Lock stock and barrel.



I talked with the manager today and he said it may be acceptable to set up the one cooler for peaches and the other for apples.



Do I need to check which cartridge is in the Sporlan TXVs?



The fruit will be coming in hot off the trees and stored for a couple weeks. I will find out more details.



I just joined RSES.  SAM is mine!



Harvey

Eugene_Silberstein

Run Harvey Run!

RUN FAST!



Sounds like you need a Presto Magic Kit to go along with your refrigeration tools.



The function of the TXV is to maintain constant evaporator superheat so, adjusting the TXV will change the superheat but will not have a significant effect on the evaporator saturation temperature.



It seems like they should be incorporating Evaporator Pressure Regulators to maintain the evaporator pressures at the desired levels.



Hotch Potch can be good, but in the world of refrigeration, it usually does not end well.



Keep us posted and let us know what you find as you continue on your journey into the wonderful world of HP (hotch potch)



Eugene

Techman

Just a Little

Oh dam it , I forget to mention you need the info off of each and every TXV ,then we can determine if there is a changeable "cage" . I was KindaSorta giggling over you getting run over by the TXV buss, my ego still has a few bruises from that very same buss, beep, beep! As The Professor said , the wonderful world of "R" HP. Before they/you  build "The Great Wall" lets let The Professor see if there is some kind of compatable cond/evap/ RH% thing, thump, thump, beep,beep, Hi Professor!LOL! Another "Trimming the Charge" system, hey Chris!!!!!

Harvey Ramer

Ego bruises.

As long as they don't cost anybody hard earned money or hurt someone, I just brush them aside and keep on motoring. I think if I want to get anywhere in life, they are a necessary part of the equation.



They do rankle for a little while though ;-)



Harvey

Techman

Just a Little.

Welcome brother! I'm envious of you, having this "problem" Harvey! You get to use lots of info to arrive at the balance of "whats handed you" , need an apprentist?

Harvey Ramer

Ha Ha

Now that would be a serious ego bruise, having an apprentice that is smarter than me LOL!!!



I like this kind of stuff though. The harder it is to figure out, the better I like it. This refrigeration business is like learning Applied Hydronics all over again. Only it is very unforgiving, where Hydronics are quite flexible.



Harvey

Techman

Just a Little

B.S. goes a long way there Harvey! More knowledgeable in something is one thing , being "smarter" is a whole different ballgame. Are you the same Harvey Ramer that I sat next to in The Professors "Psychrometrics W/O Tears" class? The same Harvey Ramer that I had to say to "say again" so I could think about what you had said?. LOLALOT.

Why did you measure the SH before the Reciever Tank instead of on the "liquid line " after the Reciever?

icesailor

Pro's:

I know that. You ALL are pro's.

My comments were directed to flaky farmers who are the true and original McGyver's of the world. If it wasn't for all those McGyver farm boys during WW ll, we would have lost the war.

icesailor

Puzzles:

Wvwe try to put a jig saw puzzle together with someone else? You can both be equally intelligent, and both can do the puzzle in time. But together, with two brains and two sets of eyes, it goes together quicker.



Asking a question of someone is like doing that puzzle. If I ask a question, or someone askes me a question, one of us needs to solve the puzzle. We both have answers that neither one of us knows we have. Until it is talked out. Hearing the discussion is like a search of a computer hard drive.

There's no such thing as a stupid question. Only the stupid questions, not asked.

RJ_4

cooler

You may need a evaporator pressure regulating valve (EPR ) on your evap coils, they will maintain a set evap pressure   I would contact the local Sporlan or Alco rep for some application help

Harvey Ramer

EPR

Correct me if wrong, they work by injecting minute amounts of liquid into the vapor line at the exit of the evap in an effort to maintain a set evap pressure. Is this a patch for an (undersized/to long) vapor line? The units with to low evap temps also have very high superheat at the condenser. To the tune of 41°. No doubt contributing to excessively hot discharge temps and possible oil decomposition.



I really need to map the system in it's entirety so we have concrete data to work with.



Terry

I measured the subcool at the exit of the condenser (before the receiver) because I wanted to know exactly what was happening in the coil. I did not want the temp reading to be affected by any pressure drops through the piping bends, receiver, sg/fd. Also pipe clamp gauges are a little hard to insulate and I did not want the condenser fans blowing on them affecting the reading.

As far as the superheat measurements I took at the evaporator, they were done correctly. The reason I was reading the temp on the exit of the txv is, temp drop=pressure drop. Pressure drop=refrigerant flow. On a system with parallel restrictions, equal temp drops should indicate equal refrigerant flow.

But then again, I've been known to try an adjust evap temps by adjusting the txv #BUSTED ;-)



Harvey 

Techman

Just a Little

patience there young "Grasshopper".

Techman

Just a Little

That injector thing your referring to is an injector thing. But this EPR thing ,just hold's back the press (P)  in the evap coil ,keeping the evap temp (T) from going below a certain point . Now, the press in between the outlet of the EPR and the comp drops. Now ,can the comp handle that slight/major change in  operating suction  press?Now, this is where that  comp operating chart/curve/"EvapTemp Operating Range" comes into play. 20*-50*F on your comp, was it? Now ,Harvey, you cannot change the given operating evap temp of a system once the system is in. That system runs , and shows you what its own ET and p/t's are, good or bad , as a result  of that piping,fittings,evap coil,TXV , then along comes Harvey. Normally, within reason, there is NO SUCH THING as a too long suction line, undersized yeah!

Techman

Just a Little

More reading info for you Harvey! 41* of SuperHeat going in to a comp is a little high. Two SH's go into the comp, five come out. they all converge in the discharge line. That total heat temp is 225-250*F app. 6" away from the comp. As Per Copeland! Tecumseh, Bristol also! Copeland has these A.E.B.'s , they are ApplicationEngineeringBulletins, one of them deals with "Overheating of Compressors" ,overheating a comp kills a comp and that is a very expensive path to take.Those AEB's are good reading for those interested parties!

Techman

Just a Little

Multiple evaps,multiple TXV's,multiple SH readings. Close ? Sure! This is not a 6-pak carburetor on a car.I seriously doubt that the "air flow" around and thru out the entire WIR is evenly distributed, so,the BTU's are not evenly spaced to give "identical " results from the 3 TXV's. Measure the WIR air temps at 8 evenly space spots around the WI , pay attention to "air flow" also.Feel the "breeze" on your face ,Harv.

Harvey Ramer

;-)

LOL