Rack Systems in Low Ambient Conditions

[air1]

This tread is outside of my area of expertise so please excuse my ignorance but I would like to learn more about commercial refrigeration.
Could one of you please provide a simple explanation of what your talking about. I get that you're discussing head pressure control during low ambiant but I'm not familiar with the valves being discussed (A8,A9,ORD,OPR). I'm assuming it's a valving system similar to a headmaster condensor pressure control that effectively reduces the size of the condensor therefor increasing head pressure.
Also, the term pumps has been mentioned several times in the same context of refrigerant. Are you referring to the compressor or some other pump? And what's a drop-leg and how does it relate to the head pressure control? And what's SCT? Is it sub-cooling temperature?
Again, forgive my ignorance, but I would really like to understand this better.

[Dowadudda]

SCT = Saturated Condensing Temperature.

Yes, the Valves A8/A9 refer to head pressure control very similair to a head master.

Pump is slang for compressor.

drop leg is liquid line leaving condenser.

[air1]

SCT = Saturated Condensing Temperature.

Yes, the Valves A8/A9 refer to head pressure control very similair to a head master.

Pump is slang for compressor.

drop leg is liquid line leaving condenser.

Thanks!

[Phase Loss]

but

pumps move liquid

and

compressors move vapor

when you compress liquid, you break compressors

when you pump vapor, you cavitate pumps

[markettech]

but

pumps move liquid

and

compressors move vapor

when you compress liquid, you break compressors

when you pump vapor, you cavitate pumps

Bored today, Mathew?

[Fridge Repairer]

Flippantly dismissing the idea of taking time to set the A8 valve during the summer because "the A8 valve is not a factor anyway. A8 does nothing." does strike me as a bit on the lazy side.

Because your a moderator, I take great offense to your statement calling me out as LAZY for not checking an A8 valve in a high ambient condition. When was the last time you tried to set a low ambient valve in a high ambient condition?

To theorize about how to set a low ambient valve in a high ambient condition is one thing this discussion was never about.

Your suggesting to the less-experienced on this website that it is routine to try to check and set a low ambient valve in a high ambient condition and that is dead wrong to do. Shame on you! Your suppose to be a professional of the highest level here.

[jpsmith1cm]

Because your a moderator, I take great offense to your statement calling me out as LAZY for not checking an A8 valve in a high ambient condition. When was the last time you tried to set a low ambient valve in a high ambient condition?

To theorize about how to set a low ambient valve in a high ambient condition is one thing this discussion was never about.

Your suggesting to the less-experienced on this website that it is routine to try to check and set a low ambient valve in a high ambient condition and that is dead wrong to do. Shame on you! Your suppose to be a professional of the highest level here.

I didn't call you out for not checking it, I called the attitude that "it's not worth my time" lazy.

My comments aren't personally directed at you and I apologize if you took them that way.

I have a HUGE problem with both the lack of training and knowledge and the lack of effort and craftsmanship put forth in this trade today.

I just took a call today, well, a call BACK where I went behind a journeyman tech and PICKED UP HIS GARBAGE after I fixed the problem that he should have, as a journeyman, KNOW DAMNED WELL HOW TO FIX.

So, maybe I'm just a bit steamed and it's coming across in my posting. Again, if you were offended, I apologize.

We can have civil discussions about theory and techniques, but what we shouldn't EVER have is discussions about whether or not we should complete a job properly.

In my opinion, if a technician isn't doing the job properly and making sure that it is done right before he walks away, that technician is a part of the problem. He either needs more training or he needs a boot in his backside.


So, as we've explained, it IS possible and fairly simple to set an A8 valve even under higher than normal ambient temperature conditions.

And, if you're anything like me and the other techs that I know, NOT setting that A8 valve, or at least making an effort to do so, is going to result not in a "check" visit when the weather gets cool, but a midnight service call when the weather gets COLD.

Trust me. Been there, done that, froze my dangly bits off fixing it.

[jpsmith1cm]

but

pumps move liquid

and

compressors move vapor

when you compress liquid, you break compressors

when you pump vapor, you cavitate pumps

pumps move fluid

vapor is a fluid

therefore, a compressor is a pump

but, not all pumps are compressors.

[markettech]

Great responses!

Ok.....now, how do you set an A8/A9 valve when the outside ambient dictates a higher SCT than your desired valve setting (summer)?

To theorize about how to set a low ambient valve in a high ambient condition is one thing this discussion was never about.

Really?!

Your suggesting to the less-experienced on this website that it is routine to try to check and set a low ambient valve in a high ambient condition and that is dead wrong to do. Shame on you! Your suppose to be a professional of the highest level here.

It can be done. I know it, jpsmith1cm knows it, Dowadudda knows it, Phase Loss knows it, several others here know it.....but you arrogantly refused to hear any more about it.

Now you are trying to say jpsmith1cm is unprofessional and dead wrong for actually completing a service call before walking out the door?

I know for a fact jpsmith is one of the most professional technicians you will ever have the privilege of interacting with.

Too bad you choose to be blinded to some great information because you're focused more on being butthurt than on the topic at hand.

[Phase Loss]

pumps move fluid

vapor is a fluid

therefore, a compressor is a pump

but, not all pumps are compressors.

Are you calling me out?!!?

Fluid Vapor is a slippery slope

[jpsmith1cm]

Are you calling me out?!!?

[Fridge Repairer]

I didn't call you out for not checking it, I called the attitude that "it's not worth my time" lazy.

Don't miss quote me. That's your quote not mine.

I said "Best to set it when you do start up. if its summer out and system is running it will be tough to set the A8. Bypass all your fans on and turn off a bunch of system circuits. See if you can creat a condition your head pressure goes below 180#. If not you won't be able to set it till cooler weather arrrives. During summer operation the A8 valve is not a factor anyway. A8 does nothing."

So where in this quote do you see its not worth my time? "The A8 means nothing" part means that during summer operation it has no function not its not worth my time. I suggest things to try and you quote that as "its not worth my time"

Your a moderator and now your miss quoting me as well as calling me out as lazy. Go have another beer...

[jpsmith1cm]

I'm not going to engage in a battle of words with you.