Need help with charging rack

[Freezon]

For most this is probably routine but its new to me. I have a new account that has phoenix hill system with 6 semi hermetics, hot gas defrost, med temp, split condenser, surge receiver, hot gas reclaim, approximately 15 W/I evaps and was under charged.
Its has already sucked down 300 lb.s. It holds 1100 lbs when fully charged. I've found two leaks and repaired. I am now trying to charge it but the receiver site glasses (4 total) will fill and half a minute later are empty. I am still occassionaly getting bubbles and sometimes instantaneously empty and full again, liq line site glass. Its obviously not my typical W/I. It pulls down so fast and cycles evap's that it seems impossible to charge it by site glass. Can anyone offer some useful advice? Its a r404 system. I keep leaning towards a constant solid liquid column in the liq sg and another tech said at least two of the surge receiver bezels should be full (which they are but then they empty just as fast) I trying to avoid over chrging. Any help would be greatly appreciated. Thanks

[Gary]

Is the receiver indoors? Is the condenser above the receiver? Does it have an equalizer line? What is the high side pressure?

[Gary]

In colder weather, if the pressure in the receiver (being in a warmer area) exceeds the pressure in the condenser (someone adjusted the fan control too low) liquid can be held in the condenser.

If the condenser is above the receiver, an equalizer line can be installed from the top of the receiver to the top of the condenser to ensure that both have the same pressure... and then gravity delivers the liquid to the receiver.

This may or may not be the problem. If you raise the pressure setting on the fan control and the receiver fills, this is confirmed.

[Freezon]

Thanks Gary, The ambients are 25 degree's. The condenser is 25' outdoors on roof only 30' away at best, receiver indoors and head psi is apprx.170 out 190's in.

[Gary]

What's the temperature in the receiver area?

[Freezon]

By the way, there isn't an equalizer line and the room temp usually no colder than low 60's. Its a well ventilated mech rm thats shared with two large boilers and open attic utiling hot gas reclaim heat. One thing I might add, when I leak searched on top of the boxes I noticed the two reheat coils were packed. Customer cleaned them and now when system runs the return line on hg is alot cooler. I'm obviously condensing more rapidly but is it to much? I couldn't hold the line before, now its no problem.

[Gary]

You might try raising the pressure setting on the fan control to see if this brings back the liquid. If this doesn't work, then we might assume that it just simply needs more refrigerant.

[Freezon]

I will check that out. Whats your opinion on this hypothetical senerio, system is operating at design, no mechanical issues, no extreme varying loads, should the level of refrigerant in the receiver always be a constant and not filling then emptying, etc..? assuming its charged accurately in that senerio. I haven't finished my research on the surge receiver but I know its trying to maintain a subcooling value and has several means of doing it but I'm uncertain if any of them will vary the level in the receiver so dramatically. and thank you for your willingness to help. I do appreciate it greatly!

[Gary]

Much depends on the specific design of the system, but in general if the change in liquid level is rapid and drastic, I would suspect that liquid is being held and then released somewhere in the system. If not in the condenser then perhaps in the reclaim coil?

The filling of the receiver (rise in level) may be accompanied by a surge of cold liquid at it's entrance, which might be traced back to the area where liquid is being held up and then released.

[Freezon]

Another person was concerned with the head psi, too. He suggested innspecting the hold back valve, I think its safe to say we are all in agreeance that the liquid is surging at the receiver. The hold back operates on psi and this system ci and co are definitelty consistant. My guess is its under charged as you suggested.I will go spend another day wiyh it and watchpsi and measure some temps. I will let you know. Thanms once again. Craig

[750 Valve]

For most this is probably routine but its new to me. I have a new account that has phoenix hill system with 6 semi hermetics, hot gas defrost, med temp, split condenser, surge receiver, hot gas reclaim, approximately 15 W/I evaps and was under charged.
Its has already sucked down 300 lb.s. It holds 1100 lbs when fully charged. I've found two leaks and repaired. I am now trying to charge it but the receiver site glasses (4 total) will fill and half a minute later are empty. I am still occassionaly getting bubbles and sometimes instantaneously empty and full again, liq line site glass.


I will check that out. Whats your opinion on this hypothetical senerio, system is operating at design, no mechanical issues, no extreme varying loads, should the level of refrigerant in the receiver always be a constant and not filling then emptying, etc..? assuming its charged accurately in that senerio. I haven't finished my research on the surge receiver but I know its trying to maintain a subcooling value and has several means of doing it but I'm uncertain if any of them will vary the level in the receiver so dramatically. and thank you for your willingness to help. I do appreciate it greatly!

So it sounds like you have basically have an Enviroguard rack (used to be licensed to Tyler - I think HP bought them out), there are plenty of instructions kicking around about charging and operation of system, will see if I can dig them up.

Look at the design of the surge receiver and you'll see its always open (vented) to the suction header and as such should not be holding a volume of refrigerant like a normal system. Does it have an SPR (saturated pressure regulator) at the rack diverting high pressure liquid into the receiver or does it have a two solenoid setup relying on electronic controls to sense and energise/de-energise via the rack controller?

[750 Valve]

section 24 should be of some help to you

http://www.hillphoenix.com/tyler/mechanical/5806448_TylerMSD-ISManual-lowrez.pdf

[Freezon]

Hey 750, I appreciate the manual. I am uncertain if this is enviroguards affordable version or what. I have not seen the SPR valve, only a bypassing vavle that someone has labeled surge, I would like to email you this system drawing and have you determine what style of surge system it is.

[BI-LO3]

you may want to check your heat reclaim value it may not be returning liq. back to the rack. feel the return line it should be warm. check and make sure your controller has atleast a 20 degree condens. temp bump up for heat reclaim and for hot gas defrost. you should have a clear sight glass and atleast the bottom glass clear on the receiver.

[Freezon]

I do have a warm hot gas return and my controller bumps up the cu psi when heat reclaim is in use. If this is what you meant. I apologize, but I am learning the CPC controller on the fly. I did clear my site glass but the 4 sg on receiver come and go, no consistency. I feel like I'm close. I've dropped approx.450 lb.s in this system since I 1st walked up to it and I obviously want to know its being done right, not to mention the customer is crapping over their bills. I did realize it is a surge receiver and not your full blown enviro. No valves or reg's on roof. It has a NO valve between in and out of receiver and its controlled by drop leg temp and psi. Thanks for your time and input. All you guys are great.

[jpsmith1cm]

This sounds like the older Hill 'Parasystems' rack.

Electronic sightglass in the liquid line and a solenoid between discharge header and receiver?

'Attron' controller in the cabinet?


If you are certain that there are no remaining leaks, set the holdback valves, typically a Parker A8 style valve for about 10# lower than the last fan cutout.

Once that is done, add gas until the first glass remains full at all times.

They DO take quite a lot of gas, expecially if you have a larger heat recovery coil. I've seen the HR coils require 200-300 pounds of refrigerant just to fill and flood.