Charging walk in coolers and freezers

[AtoZhvac]

Hi,

I worked with a tech recently who when charging walk in coolers and freezers after compressor change outs. He would cut off the condenser fans for brief periods of time. Both R-22 and 404-A.

Im just curious at what this was accomplishing and do any of you guys also do this and why? And how is this done properly etc...

Another thing say you are charging an R22 refrigeration system (large pan cooler) which requires 34 pounds of R-22. I had a heck of a time getting that much charged in. I ran warm water over the container many times to get the pressure back up to charge in the vapor.

Any tricks out there at speeding this process up? I know that charging liquid is considered a no no and the little liquid charge restrictor device is pretty slow as well.


Thanks

[craig1]

Any tricks out there at speeding this process up? I know that charging liquid is considered a no no and the little liquid charge restrictor device is pretty slow as well.


Thanks

If the system has the right valves in the right places, you can close the receiver outlet and charge liquid into the liquid line. The liquid will then flow through the evap and return to the compressor as a gas. A few weeks ago I used this method to put 92 LBS into a system in about 15 minutes.

[jpsmith1cm]

Depending on the type of compressor, I charge liquid into the suction line.

With refrigerant cooled compressors, it takes a heck of a lot of liquid to cause any damage. You have to monitor the charging, but you should be anyway.

Charging vapor in quantities much over a pound or two is a huge waste of time.

If the unit has a headmaster, there is a very specific charging procedure outlined in Sporlan's bulletin 90-30-1

As far as shutting down the condenser fans, that makes exactly NO sense.

[yotaman16]

Depending on the type of compressor, I charge liquid into the suction line.

With refrigerant cooled compressors, it takes a heck of a lot of liquid to cause any damage. You have to monitor the charging, but you should be anyway.

Charging vapor in quantities much over a pound or two is a huge waste of time.

If the unit has a headmaster, there is a very specific charging procedure outlined in Sporlan's bulletin 90-30-1

As far as shutting down the condenser fans, that makes exactly NO sense.

He might be doing thatt to get the head pressure up to clear the glass... I have a few systems that, is the charging procedure for those walk-ins. Makes no sense to me to raise the head then clear the glass on a system with head master.. but what ever..

As far as liquid charging i charge all my systems with liquid into the suction, you just need to be carfull not to put to much in to fast. I charge 10 psi above what the system is running with liquid

[TxDusty]

Don't you have to charge R-404 as a liquid?? I can't see any need to cut off condenser fans.

[jpsmith1cm]

Don't you have to charge R-404 as a liquid?? I can't see any need to cut off condenser fans.

You have to remove it from the cylinder as a liquid, yes.

[AtoZhvac]

He might be doing thatt to get the head pressure up to clear the glass... I have a few systems that, is the charging procedure for those walk-ins. Makes no sense to me to raise the head then clear the glass on a system with head master.. but what ever..

As far as liquid charging i charge all my systems with liquid into the suction, you just need to be carfull not to put to much in to fast. I charge 10 psi above what the system is running with liquid

Thanks for the reply.
Im trying to understand all of this, you say that you have some systems that use such a procedure.
If cutting the fans off to clear the glass then what about getting the glass clear under normal conditions with the fans on? Im not understanding what turning the fans off does except temporarily raising the head pressure.

Yes both of these systems that I observed this done on did have head masters so was it a useless procedure?

Thanks

[jpsmith1cm]

http://sporlan.jandrewschoen.com/90-30-1.pdf

There is the link for charging with headmaster valves.

Raising the head pressure while charging is a waste of time, really. Yes, it will clear the sightglass, but it won't speed charging in any way.

Follow 90-30-1 and walk away.

[AtoZhvac]

http://sporlan.jandrewschoen.com/90-30-1.pdf

There is the link for charging with headmaster valves.

Raising the head pressure while charging is a waste of time, really. Yes, it will clear the sightglass, but it won't speed charging in any way.

Follow 90-30-1 and walk away.

Hi

I have studied the Sporlan link and ever determining the amount of unloading that is going on would be a confusing and an uncertain thing to ever know exactly.

Most of what I work on which does have head pressure controls is walk in coolers and ice machines etc which do not have unloaders and the best info that I can gain from the Sporlan literature is to watch the sight glass while charging and that seems to be accurate at any temperature even at low outside ambients is that correct?

I dont understand this statement below from the Sporlan instructions.

"The extra refrigerant charge for head pressure control
should be weighed in now by admitting liquid refrigerant
to the high side."

My question is this. The statement occurs after head pressure would be above the pressure in the refrigerant tank so how are you able to admit liquid refrigerant into the high side? I can only assume that the system was supposed to be shut off to add the liquid to the high side?

Thanks

[thethomas4]

Front seat the receiver king valve and let the compressor suck from the refrigerant tank.

[jpsmith1cm]

Front seat the receiver king valve and let the compressor suck from the refrigerant tank.

Most units you can just meter the refrigerant into the suction line.

No problem.

[thethomas4]

Most units you can just meter the refrigerant into the suction line.

No problem.

That is what I'd normally do in this situation unless its a rack and I was using
HCFCs (Mp39, hp80, 408a) or 404a,507. these will not indicate a rise in receiver
level for a few hours.

[tipsrfine]

Hi

I have studied the Sporlan link and ever determining the amount of unloading that is going on would be a confusing and an uncertain thing to ever know exactly.

Most of what I work on which does have head pressure controls is walk in coolers and ice machines etc which do not have unloaders and the best info that I can gain from the Sporlan literature is to watch the sight glass while charging and that seems to be accurate at any temperature even at low outside ambients is that correct?

I dont understand this statement below from the Sporlan instructions.

"The extra refrigerant charge for head pressure control
should be weighed in now by admitting liquid refrigerant
to the high side."

My question is this. The statement occurs after head pressure would be above the pressure in the refrigerant tank so how are you able to admit liquid refrigerant into the high side? I can only assume that the system was supposed to be shut off to add the liquid to the high side?

Thanks

Pretty much just posting here so I get e-mail alerts when someone answers this question. I'm guessing it may be by closing the inlet service valve to the receiver and as system goes into pump-down the pressure drops in the receiver which allows you to add refrigerant?

[thethomas4]

[QUOTE=AtoZhvac;4724222]Hi,


AtoZhvac
"Another thing say you are charging an R22 refrigeration system (large pan cooler) which requires 34 pounds of R-22. I had a heck of a time getting that much charged in. I ran warm water over the container many times to get the pressure back up to charge in the vapor."

It would not take long to charge 34lbs R-22 through liquid line

[thethomas4]

Pretty much just posting here so I get e-mail alerts when someone answers this question. I'm guessing it may be by closing the inlet service valve to the receiver and as system goes into pump-down the pressure drops in the receiver which allows you to add refrigerant?

Outlet of receiver. You need somewhere for the refrigerant to store

[tipsrfine]

Outlet of receiver. You need somewhere for the refrigerant to store

Should store in the condenser shouldn't it? since this is just the low ambient charge and the receiver is really just there to store the low ambient charge? I just do big refrigeration once in a blue moon.

[jpsmith1cm]

Outlet of receiver. You need somewhere for the refrigerant to store

Isn't that what the receiver does? Store refrigerant?

[thethomas4]

Isn't that what the receiver does? Store refrigerant?

absolutely

[tipsrfine]

Isn't that what the receiver does? Store refrigerant?

What I was meaning is that without low ambient conditions the additional refrigerant would not be needed. Sporlan's charging procedures first show you the proper charge of refrigerant needed without low ambient conditions. Under those conditions a receiver would not really be needed, so that charge should be able to be stored in the condenser in a pump-down. Next sporlan directs you to weigh in the additional refrigerant needed for low ambient conditions into the "high side";which is really why the receiver tank is there-to store the extra refrigerant needed for low ambient conditions. Therefore the normal charge should be able to be "stored" in the condenser at pump-down, alllowing you to weigh in the additional low ambient charge in the receiver that has been isolated from the condenser in a pump-down.

[jpsmith1cm]

Normally, I just charge into the suction line, as I said before.