Charging 404A into a new walk-in freezer

[handyhusband01]

I am at my wits end. We bought components to build our own walk-in freezer. Larkin scroll compressor unit, 2.5 hp, 230V 3 phase, LZT025L6C with a Larkin Evaporator: LCE676BB, 2 fan single phase, 230V, liquid line solenoid, piping, 404A etc. to get us down to -20F at least. According to the sales guy we'll need 14 pounds to charge.

Started the unit, inverted the bottle to charge liquid and got it to take 2 pounds on the liquid side with a heat lamp on the compressor and charged another pound on the suction side both through the service valves. The compressor only runs with the contactor pressed in and then shuts off when it gets too hot. Next day took another 3 pounds through the suction side - no heat lamp. Nothing would go into the high side. Today I barely got a 1/2 pound in. I am waiting out a rain storm to get back on the roof and could use some suggestions - what am I doing wrong? It can't take this long to charge.
Thx.

[Northdude]

When you say contactor pressed in are you pressing it in? or is it pulling in then popping out? Is there a pressure switch on the system? is the solenoid valve opening?

[handyhusband01]

I manually hold in the button in the contactor. In the 220V control circuit is a high pressure switch (N Closed), low pressure (N Open), Time delay relay (N Open) in series with CR1: the compressor contactor. With only 1/2 of the 404A Charged then the low pressure switch would stay open - I guess. The liquid line solenoid at the evaporator in series with the thermostat is energized open when the system is supplied power from the main breaker. Doesn't matter if the compressor is running or not. I can feel the piping get slightly colder after the TEV at the evap. System was brazed together using nitrogen gas to purge.

[mafoi]

May sound funny, but, was vacuum completed before charging? Just brainstorm any possibility.

[handyhusband01]

Used a JB DV-4E, 4 cfm., deep vacuum pump, Triple vacuumed at least 12 hours each time through the manifold set to both sides. Suction line sight glass at the compressor unit shows green for dry. Oil changed in the deep vacuum pump between pulls. Liquid line solenoid at the evaporator was energized open too. Manifold gages showed that a vacuum was pulled and did not move overnight - I had to bring the pump down off the roof at night but the gage set adn tank stayed attached.

[sedgy]

hi andy, just a question , was the system pressure tested ? what with ?

[Gary]

The charge was estimated at 14 pounds. Thus far, by my count you have added 6 1/2 pounds... less than half.

Charge liquid into the suction line in one second shots. Wait for the line to warm back up between shots.

Let us know how it works out.

[handyhusband01]

Dry Nitrogen. Found 2 leaks (phos brazed joints where I couldn't see - rookie mistakes). Repaired. Soap tested all joints again. Pressurized to 140 psi using nitrogen and the gage held there for 3 days. If the sun was on the compressor unit the pressure rose to 148psi. Cooled at night - pressure back to 140.

[handyhusband01]

Will do. Right now I am up to 9.02 pounds. I have done 4 central house air conditioner units in the past and R-22 went right in. This is my first experience with 404-A and doing a freezer. So I am learning. Thx for the advice.

[Gary]

You may want to read this thread:

http://www.refrigeration-engineer.com/forums/showthread.php?t=19701

[Brian_UK]

Also, you say that the LP switch is NO, normally open. To my mind it should be NC normally closed and will go NO when the pressure drops below the pressure set point.

You said that you inverted the gas bottle when charging, do we assume that the bottle does not have a dip tube in it? (Just checking)

[Gary]

Also, you say that the LP switch is NO, normally open. To my mind it should be NC normally closed and will go NO when the pressure drops below the pressure set point.


"Normal" refers to the position of the contacts with low or no input from the sensed medium. No pressure, no flow, no coil voltage, no whatever-is-being-sensed.

So... the LP switch should be NO.

[powell]

You haven't mentiond running pressures or noises but you could try reversing two leads of the power supply which will reverse the rotation of the compressor.

See what happens.

Just a thought.

[Brian_UK]

"Normal" refers to the position of the contacts with low or no input from the sensed medium. No pressure, no flow, no coil voltage, no whatever-is-being-sensed.

So... the LP switch should be NO.
Quite true Gary, I stand corrected. :)

[FEISTY]

I don't remember seeing any pressure readings except for the nitrogen purge episode. When you began charging did you see liquid flowing thru sight glass? Was the compressor out of the electrical system with the thermostat set low so the liquid solenoid was open? Did you pressures equalize? ***** in the high side should show equal pressure on the rise on the low side. On start-up did you pull into vacuum? Was the liquid line solenoid installed with " flow arrow " in correct direction? May be basic questions but sometimes you can't see the forest for the trees. Spent an hour one day fighting no flow until I realized king valve wasn't open. Happens to all of us. Good luck !!

[handyhusband01]

Update 8Jun10. It's running. I had to call in some (experienced) help but he had it running in 20 minutes. Reason - overcharged..... Seems that my line runs were less than the sales guy estimated when he calculated the amount of refrigerant to install. It doesn't excuse me not looking at the sight glass also when I was charging by weight. So my first freezer job wiring and piping were correct but I got bit by the rookie mistake. Many thanks for all of your input.

[B G Scott]

I am at my wits end. We bought components to build our own walk-in freezer. Larkin scroll compressor unit, 2.5 hp, 230V 3 phase, LZT025L6C with a Larkin Evaporator: LCE676BB, 2 fan single phase, 230V, liquid line solenoid, piping, 404A etc. to get us down to -20F at least. According to the sales guy we'll need 14 pounds to charge.

Started the unit, inverted the bottle to charge liquid and got it to take 2 pounds on the liquid side with a heat lamp on the compressor and charged another pound on the suction side both through the service valves. The compressor only runs with the contactor pressed in and then shuts off when it gets too hot. Next day took another 3 pounds through the suction side - no heat lamp. Nothing would go into the high side. Today I barely got a 1/2 pound in. I am waiting out a rain storm to get back on the roof and could use some suggestions - what am I doing wrong? It can't take this long to charge.
Thx.
Can you advise what your past experience in refrigeration service is.
This is not being critical but it would asssit all members trying to help you with this.
If you are in the trade and need help you will get trade type help if not you will need more assistance with more descriptive advice.

[Brian_UK]

Glad to hear that the problems have been resolved and thanks for the update.