Introduction to Rack Refrigeration Components (Grocery / Markets) w/ Advanced Refrigeration Podcast

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Brett Wetzel and Kevin Compass from the Advanced Refrigeration Podcast join us to give an Introduction to Rack Refrigeration Components (Grocery / Markets).

In supermarket racks, we typically have anywhere from 2-5 compressors on a single rack (with multiple evaporators, metering devices, and sometimes even condensers). These compressors may come in several varieties (including screw and scroll) and be digital or have VFDs. They also have common suction and discharge headers.

The compressors all share oil from a single system. Oil separators can come in three varieties: centrifugal, impingement, and coalescing (most efficient). The separator would feed into the reservoir, which stores oil.

Many rack systems use several different valves. Check valves to direct the refrigerant flow, especially on heat reclaim systems and split condensers. In some cases, there is a three-way valve or a solenoid valve that controls or stops the refrigerant flow. LDR (liquid differential regulating) valves maintain the required differentials during defrost. Ball valves can be found all over a rack (liquid line, suction line, discharge line, etc.) and can isolate a line. Standard and balanced-port TXVs or EEVs may also appear on racks. There is also an EPR, which controls evaporator temperature and pressure.

Grocery systems have a drop leg before the receiver, which stores liquid refrigerant. We want a full column of liquid leaving the receiver, which we can confirm with a sight glass rather than subcooling.

Brett, Kevin, and Bryan also discuss:

Reheat and excess heat
Split condensers
Drain leg/drop leg vs. liquid line
Mechanical subcooling and heat exchangers
Counterflow piping
Hot gas vs. Kool gas defrost
Standard vs. balanced-port TXVs
Evaporator fin spacing
Cleaning components

Read all the tech tips, take the quizzes, and find our handy calculators at

Learn more about the 2022 HVACR Training Symposium at


EverythingisFire says:

This is the crossover I've wanted 😀 The "Advanced Refrigeration" guys are great.

Andy Leslie says:

These guys have their PHD in HVAC!! Pretty complex systems there! Considering taking a job dealing with rack systems. I Will have to definitely learn more but I’m ready for the new adventure!


Do they any books specifically for rack system for supermarket refrigerant ion rack?.

Jayden s says:

I want to work on supermarkets 😩

nitrofish1974 says:

Awesome been in it since 68 and still kicking 💪 😅 no man should be allowed to do as much a
s I have spent the last 25 years on mega yachts in ft Lauderdale building chillers and installing them with panels, not easy but what in life is, miss the rack race.
This podcast is awesome 👌 I am subscribed 😀 👍 😊

Alfred Hines says:

Absolutely wonderful, thank you all. It was long but guess what I have learnt a lot. You gentle, men r so knowledge and experience. Continue to do what you all do best . God, bless you all.

Kyle Hellborn says:

Please post a link to the Sporlan piping diagram. Thanks.

Michael Fletcher says:

Right-on guys! This was an awesome presentation. Thank you for this amazing podcast. What a jewel to stumble on this morning. Both/the three of you have consolidated your combined experiences while walking your audience through each component explaining its purpose and function in a way that makes its, otherwise, complexities, easy to understand and follow. A magnificent system of form and function. "Poetry of Pressurization" (Can I coin that?) I'm going to be watching this many more times to be able to approach grasping the over-arching concept of the functionality of this "grocery" – "market" or commercial rack refrigeration system.

Forty years as an Industrial and Commercial electrician; The first 20 years focusing in areas of industrial motor control etc, and the last 20 years doing commercial electrical, mainly troubleshooting various electrical systems in grocery stores out here in So Cal. Both trades, electrical and refrigeration, are essentially bound at the hip when it comes to "trouble calls" with anything involving refrigeration or EMS. My being a 63-year old (young) human sponge any and all relevant information, this was right down my alley. Though I am currently retired, being around those systems so often and for so long and not understanding the working principles was something that never sat well with me, but These working principles were always inaccessible until this morning. Thanks guys!

mike stuart says:

Would love to work on power packs again.

Saif Alameri says:

Awesome explanation!
Where we can find the PDF file of the drowning schematic? Can you upload it to a link and share it under video details?
Best regards

Cap Cloud says:

I have been in the HVAC trade for 30 years was introduced refrigeration in 1993 .I picked up rack work via OJT and got in the early 2003 .So I have worked on more then a few racks since that time.I always tell my apprentices their are a million ways to skin a cat so this trade is never going to be boring . This is especially true with rack work things are changing at a rapid pace .I worked on several CO2 systems in 2015 before I got away from racks altogether .I have to admit though I prefer being stationed at a nice quiet IT facility turning a wrench on Liebert systems etc.. to doing rack work .The beauty of this trade is their are so many specialties to pick from .


This is great. Thanks

roadkillhahaXD says:

thanks algorithm

BadTxv TikTok says:

I credit these guys with 90% of what I UNDERSTAND now about Market Refrigeration, coming from an HVAC background

Nestor Martinez says:

Oil logging on the lowest temp cases like aways also oil seps have o ring that tend too pop and causes oil fail calls and flooded starts. Also need to turn each compressor one by one and the smallest one first. Also plugged TXVs are fun after power outages. Very nice information I love seeing this the older Ref techs showing the younger tech starting in this field. It’s a lot of work but worth it.

m says:

1:40 Typical compressor room. Consumers leaving crap everywhere

De Yonte' Noel says:

Very exciting stuff. Keep up the great work Bryan!

EverythingisFire says:

Only 20 minutes into this but Kevin's Internet seems to be working great on this one 😁

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