-
RTHB LOW EVAP REFRIGERANT TEMP ALARM EVERY START
Chiller has ran fine, been maintaining for two years.
Rthb 215, 1995
Condenser flow good
Cooler flow good
Pulled gas, charge ok, put gas back in. Currently at 535. EXV STEPS 2040,
Visually inspected EXV, old and worn but checks out mechanically and electrically.
Chiller will only run for approximately 1-2 minutes before tripping low evap temp, EXV tries to close down to maintain disch sh, cannot get to set point, running 0-2 degrees. Tried manual mode and driving valve to 10 percent immediately and running chiller unloaded, still no luck,
Checked slide valve load, unload and hold ok.
Went as far as pulling all boards and sensors out of functioning chiller next to this one and installing, ran it and problem has stayed with the chiller which rules out the electronics and sensors....
Pulled evap end bell yesterday and tubes look good although I have not punched them,
Any help would be appreciated, this old girl is getting the best of me. Any possibility of a majority of the liquid bypassing the cooler from the motor cooling line into the rotors and back out the discharge of the compressor rather than dropping out the bottom and going through the orfice back into the cooler?
-
-
When those EXV's get worn, they can run in test mode with no pressure differential, but you put pressure behind them and they can stick.
-
You say flows are good, but can you share what you measured with us? Especially interested in chilled water flow. Hope you're using one gauge, moved to both ports.
In honor of RichardL: "Ain't 'None' of us as smart as 'All' of us".
-
Post Likes - 1 Likes, 0 Dislikes
-
Originally Posted by
Nuclrchiller
You say flows are good, but can you share what you measured with us? Especially interested in chilled water flow. Hope you're using one gauge, moved to both ports.
Nuclrchiller,
Condenser flow is 560 gpm at 8 delta p
Evap flow is 450 gpm at 6 delta p
I have used 1 guage to measure flow.
71CHOPS,
I also thought the valve may be sticking so I have tried working the manual king valve prior to get some sort of change but still cannot keep this online. I have been trying to get some change for a positive direction to work towards but this damn things pulls the evap down very quickly and cuts out at 30ish degrees on sat temp. Has new refer and oil filters put in December while fixing refer leaks. Logged a 1000 plus hours since prior to the repairs, chiller pulled down to 230 microns at time of leak repairs, was only 30 lbs low.
Condenser inlet water temp 70-75 degrees
Cannot get discharge temp to rise, sits around 89-98 degrees, oil separator does not get hot, checked for pressure drop from oil sep to king valve on bottom of condenser, pretty constant pressure.
Manually hooked up to evap and watch pressure drop, if I leave to txv manual 100 percent and slide valve unloaded in test the system disch sh gets to about 8 and will eventually go out on low disch sh, only way chiller will stay on long enough to not trip low suction sat temp and try to figure something out.
I can go back today and run additional test if any of this info gives you guys some ideas.
-
I dont have the conversion formula for 8 hogs head of pudding pressure drop to feet of water. Can please post that?
-
You said trips on lp, saturated temp. Evaporator may be saturated with oil. You can spend a couple of days boiling it out of the oil separator, or recover the charge and recharge as a vapor.
Five things that tell you excess oil in evap:
Normal- low ssh
Low discharge sh
Low evaporator pressure
High evaporator approach
Refrigerant injection or ecomizer overfeed(turn off)
-
Post Likes - 1 Likes, 0 Dislikes
-
I am leaning towards oil saturated refrigerant. Do you know complete history ? With information given , I would pull and distill refrigerant ; observe the quanity of oil that remained in recovery tank ( s ) . Also a refrigerant sample could be obtained and sent out to verify oil saturated refrigerant . Some people love to pump oil into machines for no reason . ( where did the oil go - it didnt evaporate )
-
Originally Posted by
CHILLERSVCMAN
I am leaning towards oil saturated refrigerant. Do you know complete history ? With information given , I would pull and distill refrigerant ; observe the quanity of oil that remained in recovery tank ( s ) . Also a refrigerant sample could be obtained and sent out to verify oil saturated refrigerant . Some people love to pump oil into machines for no reason . ( where did the oil go - it didnt evaporate )
The machine has been problem free for 3 years, in December we pulled the gas and replaced every o ring and gasket except suction, it has logged 1309 hrs since. No oil has be added since my time here. I can move forward with the process once I hear back from you on this one, cannot run loaded as suction drops off to fast.
-
Run unloaded and do the diagnostics
-
Did you go through all the config settings and set points? There is a SB that corrects the EXV steps and charge on some units.
-
Yeah bet it's overcharged. Pull 50 pounds out and see what she does. If it was charged to nameplate rather than simply putting the gas back in, it's overcharged.
-
Is this chiller built prior to Oct 1995? Is serial number between U94E0**** and U95K0****?
-
Originally Posted by
leviburck2
Chiller has ran fine, been maintaining for two years.
Rthb 215, 1995
Condenser flow good
Cooler flow good
Pulled gas, charge ok, put gas back in. Currently at 535. EXV STEPS 2040,
Visually inspected EXV, old and worn but checks out mechanically and electrically.
Chiller will only run for approximately 1-2 minutes before tripping low evap temp, EXV tries to close down to maintain disch sh, cannot get to set point, running 0-2 degrees. Tried manual mode and driving valve to 10 percent immediately and running chiller unloaded, still no luck,
Checked slide valve load, unload and hold ok.
Went as far as pulling all boards and sensors out of functioning chiller next to this one and installing, ran it and problem has stayed with the chiller which rules out the electronics and sensors....
Pulled evap end bell yesterday and tubes look good although I have not punched them,
Any help would be appreciated, this old girl is getting the best of me. Any possibility of a majority of the liquid bypassing the cooler from the motor cooling line into the rotors and back out the discharge of the compressor rather than dropping out the bottom and going through the orfice back into the cooler?
EXV MAX Travel Setpoint should be at 1670.