Comprehensive Guide to Parallel Rack Systems and CO2 Refrigeration

okay good morning guys today we're gonna go over parallel rack systems we're gonna cover kind of the basic rack

system functions and some condensing strategies as well as some co2 subcritical applications so we're gonna

cover quite a bit today if you guys have any questions I'll stop a couple of times so we can discuss throughout the

PowerPoint so so parallel rack systems there multiple temperatures the way that they run multiple temperatures is two

ways they run separate suction groups across that back of that rack on those what's called a header or suction header

so you can have what's called a split header so sometimes you'll have a dedicated rack that runs just once

suction group pressure and then it'll use what you see here if you guys can you guys see my cursor on the screen

yeah yeah okay so what you're looking at right here on the back of the rack these are EPR s they're mechanical valves

there's electronic keep ers as well but in this application you're looking at a these are Parker sport valves that we're

looking at right here with a suction stop that's where you see that solenoid on top

the suction stops you Spurs for the defrost but this is where we're actually managing the pressure of the evaporators

we're regulating that pressure and how much it's allowed to flow through that valve at one time and that's what

actually dictates the temperature of that circuit so if you have multiple systems running on that circuit the

other way that you can get a little bit of variation in your temperature is for your expansion valve superheat so those

are going to be the two adjustments that you make on a supermarket system to make your temp adjustments you're going to

use but you're gonna have your you're monitoring your EMS system and they're telling you what the temperature is but

your actual adjustments will come from you know overall calibration will come from the CPR and then your finite

calibration will come from your TX Pease you've got multiple compressors on a parallel rack system these are used for

staging so you may have other stages involved this like this this may be stage one compressor right here but you

may have a nun loader or it may be a varus speed compressor so these are Bitzer octagon compressors I do like

bits of compressors for one reason they use a bigger piston and a shorter strokes or they're a little bit more

robust for taking some liquid and some of the other brands Copeland discus is also very robust when it's taking a

little bit of a drink of liquid when it comes to these rack systems it uses a common refrigerant oil so and that's

usually you'll see that through this oil separator that's that blue cylinder there on the end this one does not have

a separate and reservoir it's all in one so usually you'll see a big canister separator with a float and then a

reservoir or if you're dealing with like a turbojet or a high-pressure separator it'll all be in one the discharge lines

will come into one separator and then it'll have what looks like an expansion valve on the back but it's

just a oil regulating about to step down that pressure as it enters the oil enters the compressor crankcase here's

the three different brands that we most most are almost all the time see on parallel racks so what you've got here

is you've got your electrical cabinet up here you're gonna see that you know that that picture before if you're talking to

us on the phone we're gonna be talking to you on the phone we're gonna get to ask you to look

at the back side of the rack that's where most of controls and valves and whatnot are as far as your mechanical

controls like I said right there with the EP RS on the front of the rack you're gonna have your your oil floats

your oil pumps for the compressors you're gonna have your visibility to discharge valve king valve which is

right here or right here on the compressor and then you're gonna have your safety controls right here your

your head pressure and low pressure and possibly your oil control so or your demand cooling control which is a D

superheating control and then this you know you'll see you this is a horizontal receiver with a digital float that's

sending a signal up to this controller right here telling you what percentage of liquid is in that receiver so over

here you have your oil separator so unlike I said you sometimes you'll have the oil separator and reservoir all and

one if your separator has the discharge line going directly into it and then it's got sight glasses on the separator

then it's acting as both components so if you're dealing with a low-pressure float oil system you'll have a separator

that goes up to a flow reservoir a separate reservoir it usually sits a little bit higher on the rack and then

that reservoir will go down and feed your floats along here which is right here this is an oil float so I will tell

you one thing about adjusting oil floats is usually they come pretty pre adjusted and you can make small adjustments to it

but if you're having to get on that oil float pretty heavily to get it adjusted nine times out of 10 just change the

flow because you're going to come back because it's and so that would be my suggestion with

floats I've seen a lot of guys try to adjust these and almost every time they're going back on the callback

because they're readjusting and readjusting they can be adjusted if you're making just like a quarter turn

one way or the other or even up to a half turn but if you're getting on a you know a couple full turns something's

happened so just be mindful oils oil guys on rack systems is probably your biggest nemesis other than like a wire

rub or something a short in the rack that takes a little bit of time as well but oil seems to give us the most

problems it seems to stump the most seasoned technicians so if you guys are dealing with oil issues by all means get

a hold of your senior technician or one of us and and we can we can help you through that that process we have a

couple classes that just cover all because it is such a such a big part of the rack systems any questions on this

guys it's a pretty basic rack I know you see in some of the other bigger markets we do we can see up to 13 press or 13

compressors and three different suction groups on the back side of the rack so they can get pretty pretty lofty and

large here's your basic diagram this is your piping diagram of the rack system you've got your refrigerants come your

refrigerant coming in through those EP ARS in the case you're gonna run that suction header at least you know 2 to 4

psi lower then what you're your lowest setting on your EP ARS if you guys are running your suction headed header

pressure too close to your EPR pressure within a pound or so you'll have a tendency with some valves to lock that

valve up so you want to make sure you're running your header about two pounds lower I would say to be safe almost four

pounds lower then your lowest suction group so you know we can talk about flow strategies on another day but you know

you can get pretty pretty dynamic and how you stage and energy efficiency on how you float the rack and stage the

rack so with these compressors so as you can see all the compressors are tied to the

same suction header so depending on how much heat load is coming in through these lines

and and raising that suction pressure there's transducers on the suction header that tell it hey bring on stage

one and if stage one doesn't bring bring that a suction pressure down to a satisfactory point within a certain

amount of time it's gonna say ramp Stage two and then bring on stage three or it might say shut off shut off too and kick

on one and three so usually what you'll see on your horsepower management on this rack is you'll have like a seven

and a half a 10 a 15 and a seven and a half a 10 a 12 and a half and a 15 so and usually when you get to the end of

the rack you're you usually doing with like a W body or and not all in lines so when you see that they're the reason for

that is because they're going to they're trying to manage you know when systems are coming out of defrost or if you're

in the middle of July or if they have a lot of doors open or if it's a busy shopping day for that location of the

year they want to maximize the efficiency of the rack and use it when they can so one thing that we do see we

don't see anymore because they size the rack pretty tight but some of your older racks they're grossly oversized and so

you'll when you we're dealing with grossly oversized racks a lot of times you know this stage 4 or whatever the

bigger compressor is won't run it a lot and it sometimes causes you problems so make sure when you guys are dealing with

rack staging you're really looking at that strategy and then how often look at your cycle times you don't want stage 1

cycle and you know does anybody remember how many times we want to see a compressor cycle in an hour

buy per manufacturer Copeland ambit's or have the same number they want to see that that compressor cycling between 6

and 8 times an hour so it doesn't seem like a lot so they want to get some good run time the

reason for that being is like when these compressors short cycle it doesn't fling the oil around and keep the oil warm

inside of that crankcase and so they want to get some good run time so when they bring that first stage on they want

that compressor to run they want it to get nice and warm they want to get that oil slinging around in that compressor

or pumping around in that compressor so they get good lubrication while they're running that's the reason for that short

cycling is really hard on the electrical as well as the compressor itself so you don't want to so a good good thing when

you're trying to balance a rack to make sure that look at your cycle times look at your PID on your control

strategies you want to see good even staging you want to see it staging through two compressors you want to see

you know not a big huge variation but most the time and when you get towards the end of the cook the rack or your

where you have larger compressors a lot of times because they've been so oversized especially this time of year

where we don't need the load you'll see that last compressor that large compressor not cycle very often that's

okay just keep just keep an eye on if it causes you problems I know some of our

satellites and some of our larger markets we actually valve off for the winter which is totally fine if you guys

have done your load calculations so as you share such a common header you're gonna obviously share a discharge header

you're gonna discharge all that heat out the same header it's gonna hit your separator

right there that's where it's it's a separator because it's exactly what it's doing the oil is separating from the

discharge gas and then it is feeding the oil through right here on this smaller line that you guys see here they step

that pressure down and then want to get that pressure only about 20 to 30 psi higher than the than the compressor

crankcase pressure so this is why you'll see our intercept on your oil reservoirs you'll see that little 3/8 line with

that with that check valve this stamp for you know thirty thirty pounds that goes over to your suction header so it's

relieving the pressure in your oil reservoir 30 pounds 230 pounds higher than your suction pressure and that

ensures that you're getting a good solid flow but you're not blowing the oil into the crankcase so that's the reason for

that line so if you overfill that reservoir and you and you put a push through that valve that check valve and

you don't allow it to shut and it's going to equalize you're gonna have a hard time getting oil to your

compressors yeah so goes up to the condenser comes

through goes through the condenser condenses back into a liquid comes down and shares a common receiver most stores

like to see these receivers anywhere from twenty to thirty percent full any given time of the year and we'll

talk about how we maintain that in the wintertime and then they're gonna send that it's gonna go through your liquid

line and then there should be a sight glass here after the dryer and then through the sight glass out to your

cases through the liquid header now this may not be a header they may use a common liquid line a lot of our Costco's

use a common liquid line header that actually feeds one line out to the stores and then brings it back on

separate suction groups separate suction lines so if you only see one line going out on some of your older stores that's

the reason why you're not seeing liquid lines coming down right next to the suction line like you would see like

maybe on a husband super plus Rach multiple compressor lubrication so we kind of talked about this a little bit

but when you're dealing with multiple compressor lubrication that's where you're going to need a couple component

you're going to need that separator you're going to need that oil reservoir you're going to need those step-down

valves to be able to drop the pressure from discharge pressure down to thirty thirty pounds above suction pressure so

that it feeds nicely into those compressors so and then it requires oil level controls and it requires that

float they're the at the compressor so if you're not using a float you're probably using like a track soil module

or alcohol or whatever I have a hard time keeping up with all the different brand changes but you guys know what I'm

talking about it has that electronic module in there that actually has a sensor inside there in the float and it

feels as the float drops the oil level drops in the compressor the thus Illinois valve opens up and allows oil

to feed into the compressor until the float comes up then it says ok and satisfies if it doesn't feel out fill up

within a certain amount of time it'll arms out locks the compressor out so we'll separate

RAK again you got your discharge that comes in you got to go through the the separator

and then it goes up to the condenser so oil separators the location is on the discharge line it's close to the

compressors in a warm location guys couple years ago gosh more than a couple years ago we had a store in Cedar City

there was had a really cold machine room and had a exposed oil separator and liquid kept migrating into that oil

separator so it's really important that your machine room stays warm this time of year so if you get into a machine

room and it's got an air vent and it's open to the outside you need to figure out how to get that room warmer

especially if you have a an oil separator in there so your your refrigerant will migrate into the oil if

you do if it's too cold in that machine room so well you need to kind of be aware of that also we need to I lost my

train of thought anyway just make sure that it's warm and make sure that you know you guys how do you know if the if

you're feeding oil or you're feeding liquid into your compressors what's the quickest way you can check that because

sometimes oil and liquid look the same there's two price bills go ahead by sale you touching the compressor the head on

the compressor yeah I just actually just tap the the oil pump oil pump if you guys put your hand on the front of that

oil pump if it's warm you're good to go look at the oil so if you're pulling foam off the top of the oil you're

probably coming in a little rich so the oil shouldn't be pulling foam off the top if it's pulling foam off the top of

the oil it's because there's liquid in there and it's oiling off the top of that oil so that's that's the that's the

visible look the the feel look is just ya touch the front of that compressor if you're touching the head and it's cool

then you got a lot of liquid in there so if you touch the pump and it's starting to get cool then you're mixing oil and

liquid so you need to make sure you know yeah if you're if you guys are doing that make sure you get you know stop the

rack get those get the liquid out or hurry and get it pumped out shut down some of your valves are flooding back

find out where the liquids coming from isolate that Val keep the rack run and get the liquid pumped out of the oil so

as soon as you can because mixing that if you're taking in that this time of year that's usually what we see we get a

lot of slugging and flooding issues in the compressors because the cold temperatures and because the cold

machine rooms so we've got to be very mindful of you know that that the first thing you guys should do when you walk

up to a machine room and start touching some heads start touching some some oil pumps you know put your hand on the side

of the oil separator so if your pump if you start to fill your pumps and your pumps are cold the next thing you're

gonna go is go to your oil your oil reservoir wherever the oil is being held and fill that see if like what's coming

in from there so because it's gonna be coming in from two ways into that crankcase it's either gonna be coming

through your suction line to rich off of a case or it's gonna be coming right through the oil separator so that's the

way you hurry and eliminate those two those two places the purpose of the separator is obviously to separate the

oil from the discharge so returns to the compressor carrying case use on large systems with long piping runs so you

know depending on the rack you're working on and stuff you'll still see crankcase heaters on those compressors

those crankcase heaters should be energizing in the off cycle and what that does is it helps keep the oil nice

and warm inside there and the off cycle and it helps boil off any liquid refrigerant that may migrate to the

compressor okay and that's for small systems - you want your crankcase energized when the compressors not

running not when it is running oil separator oil control so you got your oil level control this is a this is a

mechanical float that knot right here at the very top is where you would take off and you would make your adjustment so

and it usually has a sticker on the side that tells you exactly how to adjust that properly we like to see about 1/2

of glass a sight glass of oil with Copeland's and most of these guys you can get down to about a third and no

more than a 3/4 you know you start pushing past that you're either you're filling you're pumping oil or you're

starving it so you know not less than a third no more than 3/4 so but what you really ideally want to see is right

there down the middle on that side glass so when you guys are checking your oil you need to be not only looking at level

but also look at the color you know it should be a nice light brown and if it's a if it's a synthetic like a p OE or

some of the new oils it should almost be clear and that's why we're having a hard time telling the difference between

liquid and oil is it runs really really light and so sometimes it can be mistaken for liquid and so all you're

gonna do is this is where the oil feeds in just put your hand on the front of that bail and if refrigerants boil and

off that bail is gonna be cold I'm not sorry that fur not compressed with the bells on the backside so um but just

make sure because right here it should be warm so these are this is your valve plate and this line right here I don't I

don't really recommend grabbing it because during times of the year you can burn your hand pretty fast so I think

all of us have experienced a discharge burn but that if that line is anywhere cool it's because this is it you're

getting liquid into the system so PR you got a turd pressure regulators for these this is where we make the case

temp adjustment so a couple things about this style of valve as you know if you guys have your gauges hooked up

just remember this the way you turn the stem is the way the needle on your gauge is gonna go so if you're wanting to drop

your pressure you're gonna turn that stem counterclockwise if you want to raise your pressure you're gonna turn

that stem clockwise so and just remember when you're warming up a case it's gonna you're gonna turn it and it's gonna take

a while for that pret and that temperature to rise in the case and so it's gonna take a minute or two for your

pressure to rise so when you guys are making adjustments to e PRS you want to make an adjustment turn it a quarter

turn up and then wait now when you're going colder it goes with me almost immediately because you're dropping

pressure so just to understand that when you're going warmer you have to warm up the coil your pressures gonna take some

time to come up to where you just made your adjustment so I see a lot of guys getting on EPR as fast and then they

tighten the nut and about I don't know 30 seconds and call it a day and then what do you know we're back out there

because the case is too warmer so you want to make sure when you guys are Justin I usually go pretty warm and then

I drop it so I'll turn it I'll turn it up maybe 1/2 or 3/4 of a turn and then when I if I need to warm it up and then

I'll come back to where I want to be and then I'll watch it for about I don't know 10 minutes just to make sure that

nothing no unforeseen circumstances at the TXV s or you know the case are on the lows is causing the pressures to

rise or drop so you know hanging out whenever you guys are dealing with rack refrigeration just expect to be there

for a minute or two it's not like a single system it's not like a remote so one epr valve per section line so

doesn't mean that it's one epr per case you could have six or eight cases tied to this suction line so on the line up

downstairs but that is going to adjust the whole line up and then like I said you might have cases running to warmer

or colder within that lineup that's gonna be an expansion valve adjustment once you know you set this to the

correct pressure because refrigerant is temperature pressure related this is where you're gonna make your first to

judge adjustment then you're going to go over to your controller and see what the cases are

run that or you're gonna go downstairs to get a visible visual on it and then you're gonna start attacking the warmer

cases in the light up once you know that this is set properly and this is a picture of a an alkyl EPR so we use we

see a lot more spoiling out there so but same same concept it's gonna look at a thermistor it's gonna actually look at

the case through the controller and then it's gonna have a board to drive that valve to be more but this is a much more

finite some of these these these valves have thousands of steps thousands that's how finite they can run this this seeped

in and out to maintain the temperature that they want so a rack system controllers electronic controls increase

efficiency it's just because I think they can run more finite inputs and so they can and they can run it like a

mathematical pide algorithms to actually predict the load shifts on this rack so that it can stage you know more quickly

and more efficiently and more effectively for the load ships that happen down at the cases are down in the

stores so it gets input from pressure trim temperature sensors so you're gonna have transducers for the pressure you're

gonna have their mistress for the tip temperatures you can have outputs the cycle the compressors the valves and fan

motors and this is where you're gonna have actual boards that drive those electronic keep ers on the back of the

rack so obviously high efficiency reduces operating costs where they're getting their efficiencies guys as

they're running tighter compression ratios so they're getting more they're getting more vapor per stroke because

they're tux hiding they're running better a lot of time they'll use floating strategies which is again

tightens up that compression ratio so what floating strategies do is it really gives us a good draw of vapor per

stroke on those compressors which which really gets efficient in the runtime on those compressors which saves in energy

costs I don't know why this says commercialize but we're just gonna go with it

electronic sensors on a parallel rack so you see all these transducers and temperature sensors throughout the rack

that are sending the sending this information back to the controller so that the rack runs more effectively and

efficiently talk about head pressure control it's a good time here to be talking about that on small systems

you're gonna you're gonna run a non adjustable head pressure regulating valve or a head master is what we call

them in the field large systems and adjustable head pressure regulating valve plus a differential pressure valve

does the same thing it's just because of the the amount of load shift and the amount of BTUs that you have in that

rack system so you're gonna see these on the Headmaster's on a lot of the remote systems and some some smaller systems we

used to see head masters on racks but I haven't seen one in a while Albertsons ran a lot of Headmaster's on their racks

for years but we've we've got away from that we go to the the two valve system so here's one with a head master on the

top so what this headmaster does is as that as this liquids running from this

condenser as the Prem / ature drops there's a charge right here in this head okay and it push always it's the same

charge no matter what time of year it is it's it's an inert gas like nitrogen so it's always put the opposing this this

pressure so as long as this pressure right here overcomes this this diaphragm right here it just keeps feeding through

as soon as the pressure drops through the condenser and so the pressure drops here it's gonna push back on this line

and it's going to start filling this condenser with liquid as it does that it's going to reduce the condensing

space within the condenser which is going to raise the pressure so you may have a let's just hypothetically say

this is a one-ton condenser so as this temp pressure drops here this diaphragm is gonna push back on the seat and

slowly close and mix this valve as it mixes this valve it's going to turn this it's going to condense and stack the

liquid in this condenser so that's why we see a lot of charging issues in the winter is because we you know we're

stacking in the condenser I'm sure all of you guys have heard us say that we're stacking that refrigerant in the

condenser and so we're having a hard time getting it back down to the case but as we do that the pressure raises

because we need that pressure differential at the TX be down at the case in order to push through the TX V

so that's the reason why we have to maintain this head pressure is to get that liquid back down to the case and

enough pressure behind that liquid to push it through the expansion valve so as it does that it causes it to bypass

through this valve as this C pushes back here it opens up this right here it's gonna blend or fully shut and feed

direct discharge gas into the receiver what happens is in the receiver as it continues to condense into it liquid

because of the cold receiver outside and then again this is an outdoor unit because it's a smaller unit and then it

sends liquid down to the the case it's super important that we maintain that head pressure so that we can push

through that valve any questions on this seems to stump guys the most like during the intermediate times of the

years with ice machines and other types of equipment that you use headmasters you know we'll go back we'll go out in

the morning or in the middle of the day the things locked out on alarm will reset the ice machine or will bring on

the system and everything runs fine so we walk we do a bunch of checks we walk away it does it again a couple days

later what happened is it's getting cold outside and it's stacking this and it's not feeding enough refrigerant down to

the machine and therefore it is starving it out and then it goes into an extended freeze or whatever the alarm is but that

is the reason for it is because it's undercharged for winter time so when this starts to stack in the condenser to

maintain that pressure there's not enough refrigerant in the system and then it starves it on headmasters there

is a way to get it running in the summer you can only do this in the summer when it's never gonna when it's never gonna

bypass here if it's having a hard time or a sticking sometimes you can clip this pigtail right here at the end the

headmaster and get it to run this is a temporary fix so no matter what if you clip that pigtail you need to still come

back and change that headmaster because without fail you'll click that pigtail and then you'd be like okay it's running

and I got 80 other calls to do and then you'll forget about it in winter and then somebody will get stuck out there

in the freezing cold trying to get the headmaster changed out so lets you can clip that to get you by but it's just

it's just to get by so this is what we see on the rack systems you have that adjustable head pressure regulating

valve so and then you got that pressure differential valve if you guys notice it's doing the exact same thing we're

just making the adjustment for the resistance here instead of putting a charge in this head the adjustments

right here we can raise that pressure and we can stack that gas more or less depending on the adjustment that we make

to that valve any questions so supermarket head pressure control so is the same we see that last system that

I was showing you we see on supermarkets smaller racks this is for our larger rack systems where you'll have an

adjustable head pressure control and you'll have a differential valve both are adjustable okay

so we'll see both again if you guys look at that same concept it's all doing the same

thing you just need to understand what it's trying to do we're trying to stack liquid in the the condenser to eliminate

the surface of condensing so that we can keep that head pressure at a certain level so that as it pushes down through

this liquid line we get enough differential across the valve to feed to could get a good nice feeding pattern in

that in that refer to in that evaporator through the enemy Turing device split condensers so on your big market systems

we see a lot of condenser strategies between either the fan control or the split so to section the condensers one

section for winter both sessions for summer the advantage mullet much less refrigerant needed only the winter

condenser is flooded the other condenser is empty in the winter so what you guys will see here is you see the valve right

here that opens and shut this valve will you see no coil on this side of the valve because this one is always going

to feed the nice thing about it is if this one fails you can force it open and switch the coil over so you can still

get it happen and change up your strategies that's why that is pipe that way but this is your discharge line

coming in goes through your valve so this valve will shut forcing all the refrigerant through here and forcing all

the refrigerant to bleed out of here and so now you're running at 50% capacity so which again maintains that head pressure

so instead of stacking a ton of refrigerant in this coil to eliminate the condensing we just shut off the flow

to the condenser and send it through half the condenser to achieve the same outcome

so this is always used winter or summer this side is always feeding and then that's just gonna be it says summer but

you know whenever it gets above a certain threshold in the control strategy it's going to shut that valve

so here's just a little piping diagram again you've got your liquid going out going through your metering device going

through your power back to your compressor and then it goes from your discharge through your three-way valve

to either one of your condense one side of your condenser where it always feeds through your head pressure regulating

valve through and then you've got your differential valve there again to where it bypasses direct discharge pressure

into the valve if we need to still maintain this pressure right here this valve is ensuring that we have good back

pressure to feed through that valve right there because remember we need over a hundred pounds of pressure

differential between the outlet and the inlet to make sure that this valve gets nice liquid gets a nice push through

that TXV so and then again it's just this is what's wouldn't this valve the three-way valve shifts depending on if

it's the temperatures warm enough and it needs that added condensing to maintain that that head pressure or not so it'll

open up and it'll feed both of it both of the sides of the condenser when this valve shifts it also tells the logic in

the in the controller to run that that side of that Bank of fans for the condenser system this looks like a

nightmare so but anyway this is you get the kit you get the point you guys see you know you can get on racks this is

about a 10 compressor rack system you got you know multiple racks in this in this machine room and then you've got

all your refrigerant lines going up hitting your home runs and out to the to the cases so you see Iraq

controllers on the front there so you see right here is a thermistor so it's kind of heat reclaimed hot water

recovery tank so it's another way that we can you know maximize our heat gain so as we pick heat up from the cases

we're gonna send it through this tank we're gonna transfer that that heat to the hot to the water from the heat that

we pick out from the cases out on the floor and then we're gonna transfer that heat into the water then we're gonna

send this back out to the condenser and condense the rest of it and then send it back down to the receiver

um refrigerant leaks so electronically leak detectors pinpoint location okay guys I want to talk about this I'm still

seeing a bunch of the iceice of variation of leak detectors I'm a big fan of the H 10 cordless it it's never

failed me in 22 years so I would prefer that you guys are carrying that one I know that we have a lot of tips and a

lot of D Tech's not real happy with them so I go behind them quite often and find the leak that nobody can find so I

prefer the H 10 if we we can have those or a couple in every branch I'm not real happy with the others I know that they

just came out with a and if icon like digital that's like $1,100 is what I'm seeing that's a little much for a leak

detector we were seeing we can get an H 10 for you know around 500 bucks so on that's company provided tools so if you

guys need one or a couple for your branch please give me a call but that is the that's the core recommended leak

detector by choice so that's coming for me I mean I've just we've tried others just not satisfied with the outcome

so alarm circuit notifies a store manager when you guys are dealing with local leak detection in Iraq snout are

required to have local leak detection when you guys are going out and doing your jobs or when you're a few guys are

ever in the controller just make sure the leak detection is working it's super this is a super critical kind of pain

point for the customers if they get a big leak and they the first thing they ask is why didn't the leak detection

tell me if they find out their leak detection is not working they're not very happy about it so they're required

by the EPA to have electronically action over a certain threshold of pounds held in the system so we want to

make sure that electronic leak detection is working so the alarm circuit notifies a store manager and then hopefully the

refrigerant loss is kept to a minimum obviously if you crack a discharge line it's gonna fog up the store pretty fast

so but you know these are meant to pick up the small leaks we needed we need to check them on our PM's and we also need

to make sure anytime that we're in the controller that we're getting some kind of value reading on those leak detection

systems the average annual leak rate of a supermarkets is about 10% which is quite a bit guys I mean you think about

the amount of refrigerant at supermarkets out there your average supermarket it holds anywhere from 600

to 1100 pounds a rack so it's not a it's not a small amount that we're losing cross country this is infrared leak

detection system so in IR LD s so there's a lot of other systems out here this is just one of them so you got your

air pump it kind of pumps the air through to take the sample you get your microprocessor that takes the air sample

and sees if there's any parts for millions of refrigerant in the sample these again we're talking this is what

we're talking about on this specific condenser we actually have the receiver on the roof with the condenser you might

see that from time to time as well and like we said you know 1,500 pound of capacity that's a big boy so any

questions I'm gonna cover co2 systems real quick because we got about 20 minutes so

refrigerants refrigerant systems chiller compressors use primary refrigerant conventional HFC refrigerants so

hydrofluoric or clora refrigerants so that's like 404 now we used to use HCFCs and CFCs those have all been xed in 2020

guys they cannot sell r22 so we are done with our 22 I know there's been a big transition hopefully we're not seeing a

lot out there but they are they absolutely can't sell it anymore in about I don't know two weeks

I'm circulate a secondary refrigerant chill glycol pipe to the cases in plastic tubing so if you guys are

dealing with a glycol skin if you guys have ever had a chance to work at a supermarket that has a glycol skid we

have a few out there that we work on they're gonna use the glycol in the medium Tenth Circuit's they're still

gonna use the HFC for the low temp circuits so it's more cost-effective and more environmentally friendly it's kind

of a pain in the butt to find leaks it's from time to time just make sure that if you're dealing with the glycol skid

don't try to use your age tend to leak check the store you're probably not gonna find a leak in the in the medium

10 cases so I say that because I heard a company that was trying to do that so it was kind of funny um you're second

nature diagram so you have your 404 direct expansion system that's what the X stands for so you'll hear that term a

lot DX that's where they're using direct expansion at the at the point of evaporation

so and then you've got your your SEC your chiller system where you're gonna have a compressor

you're still gonna use refrigerant you're gonna send it through a braise plate heat exchanger or shell and tube

heat exchanger and then you're gonna run you're only gonna have a pump by the difference between a compressor to pump

pumps pump liquid compressors compressed vapor to a higher pressure vapor so no liquid liquid so this is always a liquid

glycol you know most of our customers will not allow us to put dye and glycol any more so because it makes a mess so

you just got a you kind of cut them look for that Sheen coming out of your drain lines when you have a leak in your

glycol this is a glycol skid you see your multiple pumps usually they stage there and they're usually variable speed

so then they're gonna use flow valves and circuit setters so I don't here's the chiller compressor rack so that's

that pump pumps all that glycol through a big braves plate heat exchanger on the backside of that rack and those rat that

rack circuit is just local right there typical glycol temper medium tan yes and no so what we're gonna we're gonna see a

little bit warmer temperatures of that in ours but you can get it down to as low as 18 you'll be okay so you start

cranking down into the 14 13 you're gonna start having problems with glycol as well you can't run it that cold so

let's talk about circuit centers guys cuz all these guys I've been I even was taught that these were kultur and things

these are called circuit setters so some guys call them step bow sometimes guys call them flow valves that is called a

circuit setter if you call up manufacturer and you say flow valve they'll keep asking you questions if you

call up RSD and you say I need a inch in one circuit setter they're gonna be able to help you right away so let's make

sure you guys don't know what that valve is called it's a circuit setter so write that down if you calling it something

different so it calls it something different like even on the slide I think circuitry similar to DX coils so you've

got flow adjustment valve see there you go no that's a surrogate setter valve so

there's your ball valve to shut offs for service and then your pressure trap taps so anytime you guys are adding

glycol you've got to burp the system so you just can't like make your repairs and then have a bunch of air in your

system you got to go to the highest point you gotta burp broke the system it means you got to bleed out the air out

of the circuit that you've isolated so it's usually pretty close by to that circuit you can't just like you know

make your fix and then leave that in there it's just like refrigerant you got to you got to evacuate the system air in

the system is not good yeah a couple of you have worked on these cases this is a glycol case where they're sending

through you know the pan plates the chiller pans so we've seen these at Whole Foods

mostly Barker makes them so which is he'll Phoenix now so let's talk about a co2 system so I think we're gonna cover

mostly subcritical and we'll go over what that means so co2 is a secondary refrigerant you're gonna again I've

liquid co2 you're gonna treat it more like a refrigerant again eval but like a

refrigerant it's gonna run a little bit higher pressures but you you know we're gonna we're gonna use compressors in a

co2 system this one is because it's subcritical and Hort yes or cascade is another name they call

it it's it's gonna just use a pump so you can have that liquid co2 pump go through the coil and then come back to

the system you're gonna use a hf seed refrigerant through a bridge play heat exchangers to cool that so that's what

that dagger I'm showing you the braze plate heat exchanger is right here so as that vapor comes up it's gonna hit the

heat exchanger and then it's gonna come back as a liquid and that's why you're pulling from the bottom so that you

always get liquid to feed through your evaporators so the reason why this is called

critical guys is it never reaches supercritical State so co2 goes supercritical at 88 degrees Fahrenheit a

lot of guys say 87 point 2 or 80 simply or we're just gonna say a degrees Fahrenheit obviously a lot of times it

gets warmer than 88 degrees in our region's so co2 hasn't made a big push out in our area but in they're coming up

with ways to keep that you know maintained and to keep that be able to run it efficiently in a supercritical

state so and reject that he's so the more they come up with strategies like that the more that we're going to see

co2 application because it has a global warming potential of less than 1 so it's a very good long-term refrigerant option

so co2 as a primary refrigerant upper cascade system is going to use so this is gonna be the top they're gonna call

this the top side of the circuit so it's going to use that medium temp compressors with a 404 hf c or or some

other refrigerant it cools the condenser of the lower Cascades so the condenser is that brakes plate heat exchanger that

I talked about and then the lower cascade system that low temp compressor was co2 cools the low temp evaporators

so if you if you the upper cascade system or you're gonna the top side is going to be pretty pretty textbook but

this is going to be where your evaporation happens at these Braves play heat exchangers because it's going to be

picking up the heat of the co2 and co2 is extremely efficient and it's he pick up so you can run it in a lot smaller

copper lines to to get the same amount of enthalpy as you do with a lot larger lines with the HFC it's extremely

efficient refrigerant we started up a rack in Orem Utah with a customer and we had the whole store pulled down within

13 minutes that's how efficient co2 is it was insane so all of us were standing there

like just scratching our heads how that was even possible but it was possible we watched we brought every system on we

said by the time we finished opening all the valves the first three systems were already attempt and satisfied so the

lower the low side or bottom side of the loop is it's air-cooled condenser so you got your receiver you see your upper top

side but now you're gonna see your bottom side of that loop with your receiver you're gonna have low temp

compress low temp co2 compressors so again we're using compression instead of a pump in this one so and then we're

going to send it through your metering devices so anytime you guys are used in co2 they're gonna use electronic

expansion and electronic evaporator pressure regulators an electronic head pressure control it's gonna be all

electronic because it's such a fun it has to be maintained and monitored and metered so finite that it has to be it

has to go through a heavy controller usually you're gonna have case controls in every single case you're gonna have

electronic valves or pulse valves in every single case and you're gonna have electronic head pressure control so it's

going to be you're going to have very high remote visibility to a co2 system so

and then here we have it with a low temp co2 and a medium temple I call so this would be a very expensive setup just

because of how many moving parts you have here but as you can see you can run all that through through the Braves play

heat exchangers with the suction group and a lower co2 suction group but the biggest thing when you guys get on co2

is you'll notice with co2 compressors they're much much smaller than your standard HFC compressor so and you'd be

shocked about how much these little guys can can do with that co2 any questions so I will answer one thing when you guys

get into just back here where you're not using a two-stage where you're going compression and directly into a

adiabatic gas cooler that's trans critical and the reason why that's called trans critical is because you go

from subcritical to supercritical within the same cycle so that's why it's called trans critical so when you're talking to

a co2 guy make sure that you use those terms subcritical or trans critical and don't call it a condenser call it a gas

cooler because that's all you're doing you're going from a hot gas a high-pressure gas to a lower pressure

gas the actual condensing happens in the flash tank so in from a gas to a liquid that's the difference between a co2

system and a regular HFC system that were used to is that co2 is the terminology is different if you start

calling the condenser right away that co2 techs gonna know that you're not a co2 tech so a little little word to the

wise there questions those a lot guys so hopefully hopefully that made sense you know I

would review this there's a lot of goodness here I know a lot of you guys have a desire to be a parallel RAC

technician you know I'll help out wherever I can on that so where the managers we're always looking for good

guys that want to come up and do more market work it's a lot of fun it is a lot more complex and then there's it

does require a lot more time to make your repairs so just want to be aware of what you're signing up for but it is

very satisfying to be you know a master of your craft in this area so I appreciate you guys it's time let me

know where I can help have a good day thanks Jim you guys yep thanks thank you