Training a supermarket tech

[VTP99]

[QUOTE=Phase Loss;13519191]This guy is full of the stuff that come out of a bulls rear end.


Would that be Caka ? Sounds like it's coming from his mouth.
I say bring the guy here and let us dissect him.

[VTP99]

[QUOTE=jpsmith1cm;13532861

I figured out why I was wrong....

So are you going to share that information or should we consider it just another refrigeration phenomena ?

[jpsmith1cm]

I've only been wrong a few times before, so this is hard to admit....

A fan cycling control was dropping out the condenser.

When I looked, it was running fine. Some time later, it dropped the fans and BOOM. Relief valve popped.

[Phase Loss]

ROOKIE

[VTP99]

I've only been wrong a few times before, so this is hard to admit....

A fan cycling control was dropping out the condenser.

When I looked, it was running fine. Some time later, it dropped the fans and BOOM. Relief valve popped.

To error is human. So your human.... no big deal. What I'm not getting is if you added refrigerant and there by increased pressure why would the fan drop out ?

[ryan1088]

Doesn't haunt me.

I figured out why I was wrong....

It's possible, but not on the scale and magnitude that I was seeing.

I never heard the final verdict....

[jpsmith1cm]

To error is human. So your human.... no big deal. What I'm not getting is if you added refrigerant and there by increased pressure why would the fan drop out ?

Control was bad.

Replaced it about a week later, after the relief valve dumped the charge and all has been good since.

I was there a few weeks ago and the AC is still chugging along.

[phxhvac]

It sounds like this person is intentionally misleading you on purpose. Just keep studying refrigeration, and someday you may be teaching some young tech, the correct way to service.

[smilies]

#2 can happen if a mechanical subcooler is being used to increase capacity. If the rack is a little low then the liquid is no longer at 50*F but a lot warmer. All the fixture TXV's open up, trying to get superheat down but it just raises suction (not way high, just higher than setpoint, cases warming up and all comps are running) which raises head. I've seen it happen several times.

[HvAckid82]

We just acquired an industrial boiler service company and they have techs with 10 + yrs and I would t let them change the filter in my house. It's amazing how many guys have been doing this jobs for yrs and don't know subcooling or super heat. The sad thing is the school in our area canceled first and 2nd yr classes 2 yrs running now.

[Tech Rob]

Maybe he is dyslexic and has been reading the P/T charts backwards all these years! LOL

Put him in the on-call rotation immediately. That usually separates the men from the boys.

[wannafreeze]

Ok guys. I'm training / evaluating a new coworker who has more experience than me (I have about 3-4 years only). Our company does restaurant refrigeration - in other words, small reach-ins, walk-ins, and ice machines. HIS experience is primarily supermarket refrigeration and large air conditioning.

Some of the things he says seem wrong, but he says that's how it is on big equipment. It doesn't make sense to me. Here it is:

1. "Restricted drier will be very hot" I said no, a restriction in liquid line will have a temperature drop if anything. He says not on big AC units. He says the compressor is so big it pushes past the restriction and gets hot?

2. "Low on charge will cause high suction and sometimes very high head, but only if a little low, not very low. Add refrigerant, and suction will drop and head will drop." I said totally backwards dude, flashing before TXV causes low suction. He says no, flashing due to low on charge causes the TXV to open up wide due to warm evaporator causing high suction. ??? I've never seen that, he said even ice machines will do it?

Regarding high head due to low on refrigerant, I said maybe headmaster is bypassing due to low charge? He said no, this is how large AC units with no head pressure control work.

If he's right I want to know, because I always thought refrigeration principles work the same regardless of application. He has about 8-9 years more experience than me, and I've never worked on a supermarket rack, and I've never worked on an AC unit other than a couple of residential ones for family members.

What say you?

IMHO in a unit -especially- without a receiver tank that is in a hot room and is low on refrigerant you can see a somewhat normal head pressure while the suction pressure is high because the txv is wide open.

[keviekev70]

I think this guy is good, he is good enough to trick you and get you thinking. Maybe he feels like you are interrogating him and all he does is give you BS.

Wana know how good this guy is, sit in the truck and send him in to fix a problem and see if he is productive.