[not harry]

She,s an oldie but very reliable since the sixties untill this summer. Began tripping intermitantly on low refrig temp. Might run for 2 weeks or 2hrs then trip. Not short of gas {r114] and not a float problem. Have been lucky enough to see a normally stable sight glass level drop as the refrig temp dropped and then trip out @ 31*f.
Design is 59 in /39out /32.8 r114 /3pass evap 2450 gpm @1950 tons .Condenser 85 in/ 95 out /104 r114. Oil operated vanes appear to work ok as both both solenoids open and close on command.
Could this be an economiser or agitator problem ? Can anyone explain the purpose of the hot gas line entering between the floats. Does anyone even remember these dinasaurs ?

 

[not harry]

RichardL I see your online. Any thoughts? People tell me you know these babies .

 

[RichardL]

The 19C is still a helluva' chiller...
Without a doubt tho', the most complicated and demanding compressor to rebuild.....Ever..
I would strongly suggest pulling the foat chamber cover an cleaning out the screens that stops the large debris from passing thru...
The hot gas line in question acts as a stabilizer on the float action.
Lastly, there is a fairly large check valve located on the float-box end that serves to eliminate compressor reversal during a hi-load situation. It is located on top of the evaporator and can normally be found by looking for a bulge in the insulation about 1 ft. square.
Normally should it fail partially open the motor would overheat at some point, but a loose plate on the valve can cause you exact problem by dropping the head pressure enough to have the evaporator to starve...
I installed quite a few transparent Lexan float covers when all other ideas were tried & failed...So cool to watch them double floats working....
Adjusting the minimum close adjustment higher on both floats by use of the adjusting bolts can greatly reduce the Low-Load-Rumble on the R-114 chillers are known for..

 

[chillerserv]

If your sure it's not short of R-114 then you must have verified the shutdown level in the sight glass or weighed the charge. Also, your statement that the floats are ok is hopefully proven by visual inspection. I've been fooled before on those large float balls with cracks in them. I hope you've tested those. In the old days we could drop em in hot water and look for bubbles but with todays recovery systems all the vapor would already be gone. I suppose I'd use dye penetrant on the floats.

Carrier didn't have a very good oil recovery system back in those days so the evap could get oil logged pretty easy. Has anyone added the Carrier 19DG style oil eductor or the York eductor? They're both very effective if she's got too much oil in the evap depressing suction pressure.

Of course too low of condensing pressure causing refrigerant stacking or dirty cooler tubes can also cause the same low refrigerant temp issues.

If you post a log we may be able to help. I still have all the old service literature on those units so I'll look into your HGBP question.

 

[not harry]

Ah Richard unlike me you do know something about these. Your buddy from the Lake,Harry F[remember him?] told me to pull the gas and inpect the floats. Disappointed to find everthing ok ,clean ,free moving. Was hoping to find a stuck mechanism. But they are works of art arent they? Beautifly made, definitly not cheap. Also see from Carrier literature showing location of economiser dampers, one in the cooler and one in the compressor leading to 2nd stage.Is this the check vavle?

 

[not harry]

Yes recovered more gas than expected. Have thought about oil logging and will distill refrigerant back in. Also have approval for modification to a York style oil return
Unfortunatly the condensing water in is always below design, usually 75f to keep other chillers happy. Interesting comment on the shut down level, old service report 1974 notes r114 level at 10 inches. Did he mean at shut down and is that from top or bottom?

 

[chillerserv]

That was shut down level and read from the bottom up.

 

[not harry]

Thanks Chillserve, will post log asap . My literature is iffy so any help is appreciated.

 

[RichardL]

Also see from Carrier literature showing location of economiser dampers, one in the cooler and one in the compressor leading to 2nd stage.Is this the check vavle?

No..That is "Not" the check valve I was Referring too.
The one I was talking about is accessed by a square steel cover plate about 6" X 12" on the very top of the evaporator, about a foot towards the center from the Economizer chamber & float box.
It is a free swinging stainless steel plate hanging verticaly inside a housing...One side of the plate is Evaporator whilst' the other is Condenser pressure.
Its sole purpose is to eliminate compressor backspin should chiller shut down under a good load. The hydraulic vane set-up like you have is not the fastet in vane closing.
Seldom does this "Flapper" give problems, but when it does it will drive a mechanic up the wall in finding the problem source...
As far a the float balls, I have found only one was to leak check them....Solder a shraeder valve fitting on the ball & pump that puppy up to 30-40 PSIG. Visual inspection will only make one look bad...You are looking for teeny-weeny crack and it can be anywhere on the ball..
I have a dollar I will bet against a do-nut hole that one,I would guess upper, ball is cracked....
If I forget to pay...Craig (Absorbertech) will cover the bet..(hehehe)
Leave the shraeders on the balls for the next guy.

 

[not harry]

OK from the log sheet
evap press -4"
r114 temp 34
H2O in 54
H2O out 39
r114 level 15"
gpm 2711
hgbp 100% [closed]
cond pressure 28
cond temp 92
H2Oin 77
H2O out84
vane position 28%
amps 130
Vane position and amps are not very good indication of capacity. Histoical logs never show RLA of 235 ,max is 150 with close to design H2O in/out and 6* approach.

 

[chillerserv]

Hmmm. Considering this units design conditions call for a relatively low gpm/ton cooler flow, things look pretty normal. The refrigerant temp dropping as the evap level dropped is still the best clue to this point for me. You'd better follow RichardL's float and damper inspection suggestions.