@@sparkytech8787 yeah I can try to make some longer-form videos as time goes on I keep them short because I make them during my lunches. And I try to respect my employer's time. But like the 35-minute rack video I made at my house I woke up early in the morning so I can do like more videos like that as time goes on. :)
I'm just getting into rack systems now and I have a question if it's cool to ask because I want to learn how to set EPR valves up properly and you seem pretty flow. At around 00:53 you identified the line that is holding back the pressure. The pressure we're holding back is the actual evaporator pressure, correct? You identified the line on the other side of the control as the line going back to the case. Did you mean line going back to the rack? Since we're working with and EPR valve you're not looking for a specific superheat to determine performance right? You're concerned about superheat more in terms of insuring we're not flooding back to the rack, right? I apologize if it's clear I misunderstand the operation and which side is which. What you described seems off to me for some reason and I want to wrap my head around this properly. edit: What type of control were you overriding in the motor room?
Big nuance at min 2:00 Need some homework to get that straight. Basic question: why does the system-wide suction pressure have to be at a minimum to properly set the EPR valve?
So first let's define what an epr does. It holds back a higher pressure at the evaporator coil. 1) if you don't have your system at a lower pressure than what you're setting the epr to you can't set it because its function is to hold back pressure. Let's say if the pressure at your case is supposed to be 40. And your system has a pressure of 50. EPR can only holds back pressure so if your system had a PSI of 50 your case would also have a pressure of 50. But if your system was let's say 10 psi you can now set that epr because the epr will hold back the pressure needed. 2) the valve itself will create a natural hold back. So let's say if we put in a valve and left it completely open. Just because the valve might have less volume than the pipe it might naturally hold back pressure. So let's say your system is at 10 psi with an epr installed and left as open as it can go your case might be at 15 just because of the shape of the valve. That's why it's recommended you bring your system down 5 to 10 psi below what you want to set it to. In order to set it properly. I hope that makes sense.
@@gendronhvac-r1269 It most certainly does - thanks. ... Now my brain has go back and work on ... work on what it was you did next to make that happen. Whatever it was ( all on? all off?) it's scary to newbies to be doing that to a big supermarket system, but a few more plays of your video and it should come together. Great work, thanks.
Good suggestion this is been addressed with the manager and they do have a tendency to over stock the product. But we think the main issue was the case was never meant to get that cold and it was never meant to refrigerate that kind of product. Good comment thank you for sharing :)
Not sure the case was eventually replaced. Typically I try to stay within the case specifications. If many cases have a produce and a meat mode. So typically there is a range in which they can operate the suction pressure
So my issue is this: I am currently trying to get a LT walk-in freezer down to temp. The walk in is served by two circuits on the same rack. Each circuit has two 4 ton evaporators on it. The two circuits go through defrost at different times. The evap coil ratings and specs on the rack schedule sheet state that these cases need a SST of -22° this rack is 422D so that’s roughly 8.1 psi. HOWEVER the rack has 6 compressors but one compressor is down due to failure and the store has not approved quote to fix it yet. The cut in for rack suction pressure for the compressors is 11# and the cut out is 3#. However even if 5 out of 6 compressors are running full bore the rack suction never gets below 9 or 10. If my case specs are asking for 8.1 and I can’t get below 9 am I just running in circles here? Isn’t this a perfect example to the customer for me to show them why we need to get that 6th compressor operational again? I’m not going to act like I am a refer wizard AT ALL I have been in HVAC and self contained refrigeration stuff for over 10 years and I am barely just getting my feet wet in market refrigeration now but it seems like a classic case of equipment being asked to operate outside of design specs. If I’m wrong feel free to roast me.
So at 9 psi the case should still satisfy. It's certainly not optimal but it will. But yes if you have all five compressors running all the time Full bore and it's hardly meeting suction You should get that last compressor Replaced. But in reality most grocery stores go as long as they can until it becomes a problem. I've had technicians have to shut down. Half of a store before they would replace anything. They had to do this because the system couldn't handle the load. Anyway the short answer is yes they should replace the compressor I hope that helps
@@gendronhvac-r1269 oh it definitely meets set point but it just runs very inefficiently. This groups of stores is super concerned with this and has health scores based on Time in Temperature. These two circuits are the poorest performing and as a result they keep calling us out there to “fix the issue” or “tune the system” so these circuits take less time to satisfy off and pump down. …
It's a danfoss AK-SM 880 EMS controller There a German company I like them a lot better than the Emerson E2 controller. They're much more user-friendly but I do feel like the Emerson controllers can do more. I have a playlist on that kind of Supermarket controller if you ever come across it.
@@gendronhvac-r1269 Very good. Also, if you do, could you add "units" to the numbers you mention? For the beginners in the audience, we're not always sure whether "50" is degrees or psig.
Your to quick and calm and confidant, learning a lot thanks, keep the vids coming, can you make the longer
Make the longer ?
@@gendronhvac-r1269 sorry make videos longer
@@sparkytech8787 yeah I can try to make some longer-form videos as time goes on I keep them short because I make them during my lunches. And I try to respect my employer's time. But like the 35-minute rack video I made at my house I woke up early in the morning so I can do like more videos like that as time goes on. :)
@@gendronhvac-r1269 Thanks for all your efforts regardless I appreciate all your vids
@@gendronhvac-r1269 ur quick to adjust the valve when that wasnt the problem. Step yo game up bitc* like ur mom
I'm just getting into rack systems now and I have a question if it's cool to ask because I want to learn how to set EPR valves up properly and you seem pretty flow. At around 00:53 you identified the line that is holding back the pressure. The pressure we're holding back is the actual evaporator pressure, correct? You identified the line on the other side of the control as the line going back to the case. Did you mean line going back to the rack? Since we're working with and EPR valve you're not looking for a specific superheat to determine performance right? You're concerned about superheat more in terms of insuring we're not flooding back to the rack, right? I apologize if it's clear I misunderstand the operation and which side is which. What you described seems off to me for some reason and I want to wrap my head around this properly. edit: What type of control were you overriding in the motor room?
th-cam.com/video/kMwcJxnKoMo/w-d-xo.htmlsi=APtVBKF3D-UmX4vr
I think this video will help your question God bless I hope you find my videos helpful
@@gendronhvac-r1269 I think you're a remarkable resource. We all appreciate you. Thanks and have a great weekend!
@@gendronhvac-r1269 And I appreciate the blessing. You as well...
Big nuance at min 2:00
Need some homework to get that straight.
Basic question: why does the system-wide suction pressure have to be at a minimum to properly set the EPR valve?
So first let's define what an epr does. It holds back a higher pressure at the evaporator coil.
1) if you don't have your system at a lower pressure than what you're setting the epr to you can't set it because its function is to hold back pressure.
Let's say if the pressure at your case is supposed to be 40. And your system has a pressure of 50. EPR can only holds back pressure so if your system had a PSI of 50 your case would also have a pressure of 50.
But if your system was let's say 10 psi you can now set that epr because the epr will hold back the pressure needed.
2) the valve itself will create a natural hold back. So let's say if we put in a valve and left it completely open. Just because the valve might have less volume than the pipe it might naturally hold back pressure. So let's say your system is at 10 psi with an epr installed and left as open as it can go your case might be at 15 just because of the shape of the valve. That's why it's recommended you bring your system down 5 to 10 psi below what you want to set it to. In order to set it properly.
I hope that makes sense.
@@gendronhvac-r1269
It most certainly does - thanks.
... Now my brain has go back and work on ... work on what it was you did next to make that happen. Whatever it was ( all on? all off?) it's scary to newbies to be doing that to a big supermarket system, but a few more plays of your video and it should come together.
Great work, thanks.
Could it be how they load the case and what they put in the case like packaging? Or a supply from a rtu blowing into case ?
Good suggestion this is been addressed with the manager and they do have a tendency to over stock the product. But we think the main issue was the case was never meant to get that cold and it was never meant to refrigerate that kind of product.
Good comment thank you for sharing :)
Any issues with coils icing up running at that low SST?
Not sure the case was eventually replaced.
Typically I try to stay within the case specifications.
If many cases have a produce and a meat mode.
So typically there is a range in which they can operate the suction pressure
I hate HMR cases. Great video though. Thanks for sharing.
So my issue is this: I am currently trying to get a LT walk-in freezer down to temp. The walk in is served by two circuits on the same rack. Each circuit has two 4 ton evaporators on it. The two circuits go through defrost at different times. The evap coil ratings and specs on the rack schedule sheet state that these cases need a SST of -22° this rack is 422D so that’s roughly 8.1 psi. HOWEVER the rack has 6 compressors but one compressor is down due to failure and the store has not approved quote to fix it yet. The cut in for rack suction pressure for the compressors is 11# and the cut out is 3#. However even if 5 out of 6 compressors are running full bore the rack suction never gets below 9 or 10. If my case specs are asking for 8.1 and I can’t get below 9 am I just running in circles here? Isn’t this a perfect example to the customer for me to show them why we need to get that 6th compressor operational again? I’m not going to act like I am a refer wizard AT ALL I have been in HVAC and self contained refrigeration stuff for over 10 years and I am barely just getting my feet wet in market refrigeration now but it seems like a classic case of equipment being asked to operate outside of design specs. If I’m wrong feel free to roast me.
So at 9 psi the case should still satisfy. It's certainly not optimal but it will.
But yes if you have all five compressors running all the time Full bore and it's hardly meeting suction You should get that last compressor Replaced.
But in reality most grocery stores go as long as they can until it becomes a problem. I've had technicians have to shut down. Half of a store before they would replace anything. They had to do this because the system couldn't handle the load.
Anyway the short answer is yes they should replace the compressor I hope that helps
@@gendronhvac-r1269 oh it definitely meets set point but it just runs very inefficiently. This groups of stores is super concerned with this and has health scores based on Time in Temperature. These two circuits are the poorest performing and as a result they keep calling us out there to “fix the issue” or “tune the system” so these circuits take less time to satisfy off and pump down. …
What kind of controller is that? Never seen that before
It's a danfoss AK-SM 880 EMS controller
There a German company I like them a lot better than the Emerson E2 controller. They're much more user-friendly but I do feel like the Emerson controllers can do more.
I have a playlist on that kind of Supermarket controller if you ever come across it.
"This is why I have a separate playlist for EPRs."
Can you do a video on liquid receiver low alarm but condenser is in split mode.
When I come across it i will try to post
I’ve caught myself trying to reach a suction pressure that the rack wasn’t designed for lol
Yeah sometimes it happens no worries :)
Wow! You know your $hit! Can I ask what area you work and what company
Thanks :) . I appreciate the compliment
And I would prefer not to say.
My manager has asked that I keep my company out of it.
Hard to hear; could use a voiceover in places.
Maybe I might have to in the future
@@gendronhvac-r1269
Very good.
Also, if you do, could you add "units" to the numbers you mention? For the beginners in the audience, we're not always sure whether "50" is degrees or psig.