KKT/Kraus Chiller

[ramsfansam]

Hi all -
New guy here. I have a really irritating issue I need help solving.
I work at a small hospital, and our CT scanner uses a KKT/Kraus industrial cooler. Nine months out of the year, it runs fine, but when the ambient temperature drops below 20*F we begin having trouble.
This unit is a Type KPC 108-L-U/S. It uses a 7.5 ton (i think) Copeland scroll compressor. The unit is charged with 15 lbs. of R-134a. The refrigeration unit cools down a 38% ethylene glycol/62% water mixture which is pumped to yet another heat exchanger, which cools down distilled water that cools the gantry of the CT unit. The unit is designed to cool the glycol/H2O mixture to a temperature of 6.5-11.0*C.
The unit is designed to place an "artificial load" on the refrigeration system (via hot gas bypass) at the times when the CT unit is idle. This should allow the unit to run continously. However, when the ambient temperature is around 20*F or below, and there is no heat load generated by the CT scanner, the unit shuts down. Somehow, it always seems to happen at 2 A.M. when there is a wind chill of -20.
The techs from Kraus and Siemens have checked and claim that his is the only unit that ever had this issue, but they cannot find a solution to the problem. We need this chiller to run 100% of the time, since we may need the CT for an emergency anytime.
Our refrigeration expert wants to run a frostex tape on the gas line to keep the pressure high enough to prevent shutdown. I think we should find a way to heat the glycol/water mix to around 11-12*C when the CT is idle to prvide an actual load on the system.
Has anyone else ever encountered a system like this? My boss doesn't want us to modify it too much since it is such a critical piece of hardware, but I'm getting tired of getting called in on Saturday nights...

[chemi-cool]

Adding heating element to keep the glycol is a good idea, install a thrmostate to cut it out at 10°C and a timer to let it operate only at critical hours.

[cbarcus]

Hi all -
New guy here. I have a really irritating issue I need help solving.
I work at a small hospital, and our CT scanner uses a KKT/Kraus industrial cooler. Nine months out of the year, it runs fine, but when the ambient temperature drops below 20*F we begin having trouble.
This unit is a Type KPC 108-L-U/S. It uses a 7.5 ton (i think) Copeland scroll compressor. The unit is charged with 15 lbs. of R-134a. The refrigeration unit cools down a 38% ethylene glycol/62% water mixture which is pumped to yet another heat exchanger, which cools down distilled water that cools the gantry of the CT unit. The unit is designed to cool the glycol/H2O mixture to a temperature of 6.5-11.0*C.
The unit is designed to place an "artificial load" on the refrigeration system (via hot gas bypass) at the times when the CT unit is idle. This should allow the unit to run continously. However, when the ambient temperature is around 20*F or below, and there is no heat load generated by the CT scanner, the unit shuts down. Somehow, it always seems to happen at 2 A.M. when there is a wind chill of -20.
The techs from Kraus and Siemens have checked and claim that his is the only unit that ever had this issue, but they cannot find a solution to the problem. We need this chiller to run 100% of the time, since we may need the CT for an emergency anytime.
Our refrigeration expert wants to run a frostex tape on the gas line to keep the pressure high enough to prevent shutdown. I think we should find a way to heat the glycol/water mix to around 11-12*C when the CT is idle to prvide an actual load on the system.
Has anyone else ever encountered a system like this? My boss doesn't want us to modify it too much since it is such a critical piece of hardware, but I'm getting tired of getting called in on Saturday nights...


How can anyone go about getting service manuals and training. Not having alot of luck with support. The market is good here and there is a shortage of good techs. This equip is not the norm, and I agree it is critical, but most systems I see that are critical have a BACKUP chiller. Every imaging place I've been to only has one chiller, and when it is off, its like the end of the world and they are loosing tons of money. So where's the backup chiller?

[sedgy]

hi ramsfansam , the problem couls be that on start up with the ambiant being so low its going out on L-P, to prevent this a cold start kit could be fitted all is requiered is a second L-P swich and a timer, so on start up the 2nd L-P swich takes over, and once the unit warms up<10 mins< the second L-P relinquishes controle.

[1ton4x4]

the kpc108 should already have a built in heater in the glycol loop. Heater is labled 5E1 That should be checked to see if it's functioning, though it only runs when the unit is on. If the problem only appears when it's extremly cold with a wind I have been advising two things. 1. install a wind block in front of the condensing coil approx 8" (piece of wood or sheet metal) 2 advise the customer not to shut down the CT in extreme cold. Yes they should shut down periodically the get the CT updates but on the extreme cold days have them keep it on at night.
Hope this helps

[1ton4x4]

Forgot to mension adding heat tape to the refrigerant lines will not help unless you add check valves, or it will just push all the ***** to the coldest spot the condenser. It will also void any warranty on the chiller and the certification of the CT and chiller. If you want to change the design by adding anything to the unit contact Kraus and the scanner manufacture