Rack Systems in Low Ambient Conditions

[markettech]

You could also set it at the lowest point local ambient will permit, then reduce the setting per the X# per turn (I've seen it written somewhere) to approximate target desired.

I am aware there is literature out there which details x psig per turn, but I'm still not following you.....can you expand on this a little?

[jpsmith1cm]

I am aware there is literature out there which details x psig per turn, but I'm still not following you.....can you expand on this a little?

Ok, let's say you're trying to set an A8 for a 65 SCT, but it's 85 out.

So, dial it in as low as you can, say 90-95 SCT, then figure out how much lower the pressure needs to go, adjust the stem blind per the pounds per turn formula to reach an approximate setting.

[Fridge Repairer]

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.

[markettech]

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.

This thought process befuddles me.

Since the A8 valve is out of play during the summer it is okay to do a half-assed job of servicing the customer's equipment, apparently.

I can't count the number of follow ups I've seen over the years by techs who are either too lazy to do their job, too dimwitted to think outside the box, or both.

Bet those customers love seeing a service invoice come through in December resulting from work that was actually done the previous June....

[Dowadudda]

You can dial a rack with low ambient valving arrangement any time of the year in my opinion, unless it's so hot it's not possible. It's certainly easier to do on a cold day. Less time and work.

One regulates pressure inlet to it. One regulates the pressure difference of the inlet to the outlet. Manipulate the rack to give you those pressures and dial it in. if no one messes with it, it ought to perform on that low ambient day no problem.

This is why seeing 50%-60% receiver in summer may be normal. We need that liquid in winter to stack the condenser.

This is why splitting is nice to have. If we split we reduce that overall charge. In split, and still require the stacking to keep minimum receiver up, I only have to stack that active condenser. much less liquid needed.

In Michigan and Wisconsin, where I came from in the trade. You always had to fan cycle, obviously. You almost always had equipped Split either automated or manual means, You always had low ambient valving. And on them cold days, really cold days, you may have had to add gas to stack that condenser so much so, that if you never did anything else to that rack, in June you would see a receiver at 60% or more. Not abnormal in that situation. It did what it was suppose to do when it was suppose to.

So now I think about applying the knowledge gained on floating head. All the low ambient stuff above stays the same. Cause in the strategies of floating I have been taught, we kinda basically stop anything at 65 to 70 SCT depending. And I have to ask myself, what happens if it's so cold out, like I have years of time on, and even with any fans off, were still dropping. \

Well. Easy. Still split. Still Stack. If we go below our limit block of floating, where stop doing anything, then we have other lines of defense.

I would love to go back up north and put this all in together. You have no idea how many stores up there miss the savings between 70 SCT and 95 SCT. And it's because the mind set is about them Cold Winters. So not much is concentrated on the sweet spot. It's literally amazing. How much money is sitting up there ready to be made.

[Fridge Repairer]

This thought process befuddles me.

Since the A8 valve is out of play during the summer it is okay to do a half-assed job of servicing the customer's equipment, apparently.

I can't count the number of follow ups I've seen over the years by techs who are either too lazy to do their job, too dimwitted to think outside the box, or both.

Bet those customers love seeing a service invoice come through in December resulting from work that was actually done the previous June....

To be honest, I can tell I'm not nearly as smart as you BUT, your the one that is to dimwitted that your the one un-able to think outside the box just by the nature of your response. Let's be honest here if you the start -up guy did your job correctly you would have set the A8 and A9 valve at start up while you were charging the system.

I don't understand how you can call my response lazy and ignorant. My response was accurate, knowledgeable and understandable. Where do you get off be-rating me from?

[jpsmith1cm]

To be honest, I can tell I'm not nearly as smart as you BUT, your the one that is to dimwitted that your the one un-able to think outside the box just by the nature of your response. Let's be honest here if you the start -up guy did your job correctly you would have set the A8 and A9 valve at start up while you were charging the system.

I don't understand how you can call my response lazy and ignorant. My response was accurate, knowledgeable and understandable. Where do you get off be-rating me from?

Markettech is one of the finest techs I've had the privilege of speaking to.

Of course this should be done during start up, and I'm sure that he does it when he starts equipment up.

That said, things change, A8 valves require repair, adjustment and other service throughout the life of a piece of equipment and that service cannot always be scheduled when it is most convenient for the technician.

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. This is the attitude that keeps supermarket guys working long hours when they should be at home drinking a little beer or spending time with their kids. Summed up, that attitude reads:

It's not important today, so I don't care. I'll fix it tomorrow.

That attitude has kept my bills paid and my belly full for years and will continue to do so for as long as guys have it.

[Fridge Repairer]

This thought process befuddles me.

Since the A8 valve is out of play during the summer it is okay to do a half-assed job of servicing the customer's equipment, apparently.

I can't count the number of follow ups I've seen over the years by techs who are either too lazy to do their job, too dimwitted to think outside the box, or both.

Bet those customers love seeing a service invoice come through in December resulting from work that was actually done the previous June....

It's your job to train your techs that your in charge of, right? Sounds like your not doing a good job of training your techs if you constantly are going behind YOUR guys. Don't be so PC. You make others afraid to ask important questions out of fear of responses like yours.

[Dowadudda]

what ever fridge. your the one dreaming up controversy. Pat is a fine mechanic. As is JP.

[Fridge Repairer]

Touchee! Your right about me. I'm not going to waist the customers time trying to set a valve in conditions that are not favorable to set it. As long as I have a strong receiver level, the amount to which depends on ambient, I can be PC too, I will leave the store and sleep well all night long knowing when I go back to change a motor or whatever if the conditions are favorable to check it, I will check it then. That's just me though. Yall can waist your customers time messing with a valve that doen't need messing with so yall can sleep well next winter however how many months away that is.

[markettech]

Let's be honest here if you the start -up guy did your job correctly you would have set the A8 and A9 valve at start up while you were charging the system.

I don't understand how you can call my response lazy and ignorant. My response was accurate, knowledgeable and understandable. Where do you get off be-rating me from?

My intent is/was not to berate you. In hindsight, my response to your post could have and should have been presented in a more tactful manner. For that, I do apologize.

That said, to make an assumption that the only time a holdback valve needs to be set is during a store commissioning is short-sighted at best. But then to also suggest disregarding any attempt at setting the valve during higher ambient conditions does seem to indicate a rather flippant attitude toward the customer as well as the job we are paid to do.....IMHO.

We get paid very well to do our jobs right....the first time. How does pushing off the proper setting of a valve equate to anything other than laziness and/or ignorance? If it can be done, it must be done (again, IMHO).

For the record - I'm not in charge of anyone. I don't have 'guys'.

The process I described earlier has not failed me yet. I'm not saying it's the only way - or even the most efficient way to set the valve in the summer.....just that it seems to work for me.

It sure would be nice to get back on topic and discuss/debate how to accurately set an A8 valve no matter what the OAT or system conditions rather than personally attacking one another.

[markettech]

what ever fridge. your the one dreaming up controversy. Pat is a fine mechanic. As is JP.

Well to be honest, none of us knows it all - except for one guy.........and he's not here today. .........

[engineerdave]

At one point or another, a number of the guys currently commenting on this thread have slapped me down over the years. Sometimes without any lube. Those slapdowns are responsible for a fair portion of my wages today. Don't take issue with these guys, Fridge, take their advice.