Help with charging

[Milk man]

New walk in cooler for a liquor store.

Customer provided equipment.

Four 5200 btu evaporators with TXV.

R-404a

Condensing unit: Copeland FJAM-A300-TFC-020 with fan cycling for head pressure control.

135 feet of line set mostly 1 1/8 and 5/8.

Receiver capacity is 10.3 pounds. The rep could not tell me if it was 90% capacity or full. Receiver is Blissfield B0600012VR-140.

Rep advised me to charge to a clear sight glass. I want to shoot for 12 degrees Subcooling, but don't want to overcharge and have problems when it pumps down on it's off cycle.

I also want to set about 8 degrees superheat on each of the four TXVs. I can take the line temperature close to the buld, but don't have good access to and suction line taps. Is it okay to use the suction pressure reading at the condensing unit 135 feet away to figure superheat?

[skpkey9]

Milk man - You can't charge a system with a receiver with sub coolong , it is what it is..
Charge to a full sight glass and and add 10% then pump down watch high side needle for rise over 5 psi if it does you are over charged if it does not run torch up and down receiver a couple of passes then take your finger and run it up receiver where the temp changes from cool to hot is your liquid level, Not To Exceed 80% volume,.... You are now charged...


Hope this Helps...

[jpsmith1cm]

Agree. Forget about subcooling. Clear the glass.

Now, are you certain there isn't a headmaster hidden behind the receiver? What is the lowest ambient where you are? Fan cycling is really a poor method for low ambient control. Where is the LLSV?

If you have a headmaster, following Sporlan's 90-30-1 charging guidelines are the BEST way to ensure proper charge over all conditions.

As far as superheat, I'd check the pressure at the evaps if possible. If not, add a pound or two and use the reading from the unit. You'll be OK.

[ZeroTolerance]

Headmasters... Pain in my asssss

[skpkey9]

About to change one in about 20 minutes ....Warranty Manitowoc

[jpsmith1cm]

Headmasters... Pain in my asssss

Live where it is very cold and you'll change your tune.....

[hvac wiz 79]

my biggest issue with headmasters WAS my ignorance on how they work .. once it soaked in I prefer them over fcc any day of the week

[rayr]

Live where it is very cold and you'll change your tune.....

Ditto on that!!!

[powell]

See below

[powell]

Condensing unit: Copeland FJAM-A300-TFC-020 with fan cycling for head pressure control. This model did not come from Copeland with a FCC. If it has one then it was installed by others.

135 feet of line set mostly 1 1/8 and 5/8. the liquid line is too big, 1/2" would be the optimum size.

Receiver capacity is 10.3 pounds. The pump down capacity of the receiver that Copeland used is 16.3 lbs. It must have been changed or the rep was incorrect.

powell

[Milk man]

Thanks to all. Will take everyone's advice.

[Milk man]

Agree. Forget about subcooling. Clear the glass.

Now, are you certain there isn't a headmaster hidden behind the receiver? What is the lowest ambient where you are? Fan cycling is really a poor method for low ambient control. Where is the LLSV?

If you have a headmaster, following Sporlan's 90-30-1 charging guidelines are the BEST way to ensure proper charge over all conditions.

As far as superheat, I'd check the pressure at the evaps if possible. If not, add a pound or two and use the reading from the unit. You'll be OK.

I didn't see one but assumed there was one. I called the leed man this morning and he told me no on the headmaster and it is set up for fan cycling.

We can expect zero degrees for a few days each winter.

LLSV in cooler just before the first evaporator.

[skpkey9]

Great call Powell I was in a zone when I answered this morning , It didn't look right then, and started to get busy so I just answered his question.... But great call...