Walkin cooler question

[redwhitekat]

hey everyone i have a walkin cooler giving me problems, its got a ref plus evap coil with a ton and half tx valve its a brand new coil another company installed in march, anyways i cant get it down below 50 *f, i tried setting up my superheat but temp on coil never changed as i was adjusting tx, it was at 54*f, comp was runing at 15 psi suction 150 head, so high superheat, so i changed out the valve, this time i opened tx all the way, waited about 30 min and evap coil temp dropped to 47 *f, still runing 15 psi suction, now i'm questioning the size of the coil and tx, but more the tx, looking at ref plus web site, the lsa 1601 coils can go up to 2 ton at 15*ftd, anyone know what ftd means? anyways my next action was to increase the tx to 2 ton, its 134 system got a clear sight glass, etc comp pumps down pretty good,
any suggestions ?my box temp while doing all this was around 52 *f. and my coil discharge was at 47 48 *f.

[crymtide]

With the txv opened all the way you gan expect a high temp suction line. Shut the unit down and close txv. Then open two turns and start checking temps and superheat. open valve slowly. maybe once every ten minutes. AT THE START YOU MAY HAVE BUBBLES SINCE YOU'LL BE STARVING SYSTEM, but as you go along it will straighten out. take your time, refrigeration done properly takes time. Also anytime someone else does install I suspect the install. Model and serial numbers from the compressor and the evaporator and a visit to a reputable refrigeration supply will provide the answer on the txv being the right one for the system. I went to a wedding chapel one time that had a new cooler installed taht wouldn't cool. The owner had his A/C guy install it. It looked fine to start with but was flooding back to the compressor on the suction side. A close search revealed that he tied the suction line in without a txv. First time i had seen it, but now one of the things I look for.

[jpsmith1cm]

Has the unit EVER worked properly?

Let us start with that question.

If yes, then stop trying to re-engineer the GD thing and work to repair it.

Let's work in that direction.

You have a 15# suction line on R-134a. That sounds good to me. Not going to question the compressor too much.

What about the drier? Plugged?

TXV power element? Inlet screen?

[ColdairGuy]

Yep First Question....Did it ever work satisfactory?

Second, a TXV should be adjusted in increments.

FTD= Farenheit Temp. Difference

[bunny]

When in doubt, call the equipment manufacturer and see which TEV they recommend for the application.

Deciding to upsize the TEV without any information is not the best route...much like you'e like your doctor to run a few tests before "deciding" that you need a heart transplant.

[james122964]

hey everyone i have a walkin cooler giving me problems, its got a ref plus evap coil with a ton and half tx valve its a brand new coil another company installed in march, anyways i cant get it down below 50 *f, i tried setting up my superheat but temp on coil never changed as i was adjusting tx, it was at 54*f, comp was runing at 15 psi suction 150 head, so high superheat, so i changed out the valve, this time i opened tx all the way, waited about 30 min and evap coil temp dropped to 47 *f, still runing 15 psi suction, now i'm questioning the size of the coil and tx, but more the tx, looking at ref plus web site, the lsa 1601 coils can go up to 2 ton at 15*ftd, anyone know what ftd means? anyways my next action was to increase the tx to 2 ton, its 134 system got a clear sight glass, etc comp pumps down pretty good,
any suggestions ?my box temp while doing all this was around 52 *f. and my coil discharge was at 47 48 *f.

I bet the compressor is bad, high side valve leaking, been there done that.

Jim

[redwhitekat]

thanks guys for all the responses, im not sure if it ever worked properly, because i cant get a straight answer from these guys, its in a big supermarket chain, inlet screen clean, i put in new bulb and tx valve, druers were changed when they did the coil, and i checked, i havent been back since i posted the question, but i will go there tomorrow and see how its doing, if its still at 50*f, then im gonna have to find a way to get more refrigerant into that coil, to get my 10 degree or so superheat, also compressor old and new coil, so i can go up to 2 ton, if its a 15 ftd, if can figure out what it actually means in my application.

[james122964]

thanks guys for all the responses, im not sure if it ever worked properly, because i cant get a straight answer from these guys, its in a big supermarket chain, inlet screen clean, i put in new bulb and tx valve, druers were changed when they did the coil, and i checked, i havent been back since i posted the question, but i will go there tomorrow and see how its doing, if its still at 50*f, then im gonna have to find a way to get more refrigerant into that coil, to get my 10 degree or so superheat, also compressor old and new coil, so i can go up to 2 ton, if its a 15 ftd, if can figure out what it actually means in my application.

Pump the compressor down and see if it holds at the service valve on the suction. Does the compressor seem hotter than normal? is the amp draw low?

Is the liquid filter after the site glass? if not, I got 20.00 on a bad compressor, if it a semi you may be able to get a new valve plate for it.

Jim

[redwhitekat]

comp does pumpdown, but it bleeds back a bit from the discharge, not runing hot, but also not cool on the belly i guess because of the high superheat, sunction line warm coming back. has a brandnew filter after sightglass, comp would be my next mode of action.

[ColdairGuy]

If your leaking back through the discharge your going to want to replace that valve plate or compressor anyway.

Is this a rack or single system?

[redwhitekat]

this is just a single system.

[james122964]

comp does pumpdown, but it bleeds back a bit from the discharge, not runing hot, but also not cool on the belly i guess because of the high superheat, sunction line warm coming back. has a brandnew filter after sightglass, comp would be my next mode of action.

it should pump down and not bleed back, the valves are leaking.

Jim

[jpsmith1cm]

Filter AFTER sightglass.

Better check it again, friend. Pressure difference is the best way




Discharge valves? Maybe, but it doesn't sound that bad.

[RayD8630]

Filter AFTER sightglass.

Better check it again, friend. Pressure difference is the best way




Discharge valves? Maybe, but it doesn't sound that bad.

JP? Could you take a temp reading across the two sides of the filter dryer and shouldn't that reading not be over 1 degree Delta T?

[jpsmith1cm]

JP? Could you take a temp reading across the two sides of the filter dryer and shouldn't that reading not be over 1 degree Delta T?

http://hvac-talk.com/vbb/showthread.php?t=299592&highlight=Pressure+drop

Read here.

Rather than me trying to explain it again and not doing it correctly.

Marc is a very intelligent guy if you can follow him.