Trane Rtaa 270 with oil and low suction trouble

[jimbob73]

You run the chiller at 0 to -11 degrees F with solution good down to 27 degrees? Am I reading this right? I would assume setpoint is Celsius because chiller setpoint I think only goes down to 0 F?

[jimbob73]

At setpoint of 0 to -11 C = 32 to 12.2 F, Your short on freeze protection/glycol. While there may be burst protection with flow, Solution would turn to slush which would cause pump efficiency/flow to drop and cause problems within the evaporator.

[supertek65]

Hey guys. I think I have my oil nuisance problem fixed. The unloader valve had a dirty pill filter. I took it out and discarded it. Last time I checked when it started it was around 46%. It never tripped on oil flow after I did that. Now my low suction happens after the unit loads up. The system is very low on glycol. The technician that tested it said it was only 27 degrees. Past the EXV it frosts into the evap but, It is not frosted going to comp. I believe I have an RTAC next to this one and the digital display is showing a 44 suction it shows running normal. Could low glycol cause a low suction since the heat transfer is not as great with just water? Oh by the way we run our chilled water systems at 0 to minus 11. also unit shows 74 then 77 and after the unit runs then it goes back to 74 until unit goes into 7e then shuts down.

i believe heat transfer is better or more thermal conductivity with water
than with glycol, you lose btus with glycol

[Chiller Guy]

The best heat transfer is acheived using water alone. When you add glycol the heat transfer starts to get worse and the unit has to work harder to pull out the same amount of heat. Thus the reduction in capacity. The more glycol, the less capacity. There are capacity correction charts for that machine (and others) when using glycol.
There are no parts,tubes, or anything inside the oil seperator. Just a big, ugly, round "U" tube for oil seperation by centrifugal force (as mentioned earlier).

[Healey Nut]

Ok well done on finding the dirty pill filter . did you check the amperage at start up ??
At this point I really think you need to get hold of not only the service bulletins I gave you numbers for but also the main IOM IOM 3 it is a very informative manual and explains how to access all five menus and all the settings for each men . It also shows diagrams and cut away drawings for compressors and oil circuit etc.
One setting to check is in menu 4 for LWT below 38degrees you have to enable the EXV low solution temp gain compensation to properly control the EXV at low LWT"S. This may be your issue ??
All the info is available from your local Trane Office (or possibly Jayguy if you ask nicely) Im not computer savvy enough to know how to send them to you .
also check the chart in the IOM that explains what the ideal settings are for the menu 4 items that Jayguy mentioned ,they are critical and so is the recommended glycol concentration .
good luck Graham

[Healey Nut]

I made a mistake about the EXV compensation setting its in menu 5 and its for LWT settings below 40degrees f . It has to be set to enable .. sorry for the confusion . graham

[jayguy]

to jayguy I can only get into 3 menus on this system

i posted this last night but it seems to have disappeared so here it is again...more or less.

0F is the lowest setpoint you can have.

Trane has 6 menus in the controller. the other 2 menus are "hidden" and you need the password to access it. Trane hid it really well...in the IOM on page 93...duh!

i think that you may have some inaccurate sensors (sat evap temp and/or comp temp sensor), so i would check them against a well known thermocouple. but like i said earlier, get those values and get your glycol levels up.

running codes...
74: Run Normal
7E: Run Unload
77: Run Evap Limit

the chiller will run to maintain the load until the "saturated evap temp" hits the number programmed into menu #41. it will then unload (code 77) to maintain the "saturated evap temp" above its minimum setpoint (menu #41). at this point you will start losing your load.

good luck.

[Healey Nut]

Six menus ???? you must be thinking about the chinese take away down the street (LOL) theres only five that I know of ??? Graham

[Chiller Guy]

There are six (6) menu's but it can be argued that there ony 5. They are:

Operating Display - Menu #0
Service #1 Display - Menu #1
Service #2 Display - Menu #2
Auxillary Options Display - Menu #3
Factory Display - Menu #4
Factory Display - Menu #5

[jayguy]

Six menus ???? ...

menu P0.

must be computer guys who came up with menus that start at 0!

good luck.

[Healey Nut]

i

[Healey Nut]

Okay. Okay There are Five Menus in which control setpoints and parameters may be selected or adjusted ... is that better ?????? I hate computer geeks ??????? not you jay .

[jayguy]

...I hate computer geeks ??????? not you jay .

dittos to you too!

good luck.

[badtech]

Hey guys I have not forgotten about you. I have been busy working on other stuff around campus. All of your guys input is great. I found that two of my pump drives in the building were put in bypass. Can you believe that crap. I found one too be working good and the other had a bad dc buss fuse on order now. graham, your help was tremendous. I have gotten with the local trane tech guy and have a nice binder on service bulletins for the Rtaa chillers. I will not go this long on checking in again! thanks to everyone badtech Oh hell I have been working on a Pool Pak and Carrier chiller. JUnk!