Rtaa 300 Trane Chiller

[seraaco]

Hi This Chiller Displays a 77 and It Means Evaporator Limit When Starts In The Morning I Think It Needs Refrigerant The Sight Glass It's Not Clear Pressures Ls 60 - 65 Psig Hs 220 - 265 Psig After A Few Tries It Stays Working All Day And Never Appears Again Until Next Start. I Allready Added Like 40 Lb Of R-22 Because Pressures Were Too Low Ls 35 - 45 Psig Hs 200 - 220 Psig

[rotaryfrk]

. I Allready Added Like 40 Lb Of R-22 Because Pressures Were Too Low Ls 35 - 45 Psig Hs 200 - 220 Psig

How about the leak? Did you fix the leak yet?

[jsherhvac]

Is this guy serious

[-80 chuck]

Just Add 100 lbs more and let us know how it's running.

[Allen Anders]

Try checking subcooling should be 10 -12 f at full load and make sure that that evap water flow meets chart in machine . Water flow can change charge
and subcooling will tell you that

[Healey Nut]

Yeah but what about the leak . whats next hook it up to a hundred pounder and a solonoid valve and pressure control so it tops up automatically . If its short its leaking ,FIX IT .

[jackt]

FYI, I've had several problems with sensor failures on Trane RTAA chillers.

[lipsoffurry]

Did you look for any LARGE oil stains?

[HVACSAMTY]

the pressure diferential in the cooler?

[seraaco]

easy boys some one else removed the compressor from the system (system 2) only one comp of 1oo tons. and left the system short of refrigerant thats why i added that ammount of r-22 i allready checked for any leaks and didn't find any by the way the chiller didn't reach the set point before the refrigerant charge. i'm just asking if i'm still short on refrigerant, because it looks like ; but i dont want to overcharge the system if i change the liquid refrigerant temp the code 77 does not show up any more.

[nchvac]

I am curious if this evap limit is a high limit or a low limit. If it is a high limit, you may need to throttle the water back a little until it settles out instead of starting it multiple times. Anyway, let me know.

[Healey Nut]

Ok Lets start at the beginning . A77 is low evap limit .Is it set correctly based on what the IOM says for the appropriate CWLS, You say it only happens in the morning presumably at the time the BAS system starts it up. What else is going on in the system at that time ie are the AHU"s running is the chilled water pump a VFD if so what speed is it at ,is the system a primary and secondary loop etc etc . What i am trying to say is that there are too many variables to just say the chiller has a problem. you need to look at the system.
Changing a compressor on an RTAA can easily be accomplished without any refrigerant loss.
The sight glass tells you two things .There is refrigerant in it and it is flowing ,it has no relavance as to amount of charge . This is determined by subcooling or by weighing in the charge.
you need to have the correct delta p on the evap and then and only then can you check subcooling to determine charge .
It sounds to me as if you need someone with more experience on this kind of chiller to help you out here .

[Manu1]

If the chiller is A77 means is limited by low ref temp on the evap, and that could be caused by several things: what is the chilled water SP? what is the low ref temp cutout SP? what is the subcooling and what is the real superheat? (not the one read by the UCM) this chiller must mantain 8°F superheat but I've seen a bad suction or sat evap temp sensor could create a false alarm or false operational condition.

Subcooling (SC) and superheat (SH) will tell you if the chiller is properly charged, don't use the sight glass as a reference is not a good indicator, another thing to look for is temp drop across the filter dryers on the liquid line.

Hope this helps!!

ps. standard SC for this unit is 11 to 20 depending on ambient temp.