New to chillers

[Scotty58]

hey i just recently started working for a hospital. they have two trane low pressure chillers i believe(200 ton and a 300 ton) and a 150 ton carrier chiller. I went to hvac school but never learned anything about chillers besides what i read in our book on my own. I learned a little in the short time i've been with the hospital. Us maintenance guys don't really get to do much work on the chillers. Usually trane technicians are called in. I still want to expand my knowledge on them though because they interest me so much more than regular residential units or rooftop units. Wondering if you guys have any suggestions of books i could read or articles? I'm hoping to get the manual on the chillers at the hospital so i can read them. Any help or advice or words of wisedom would be much appreciated. Hoping to maybe get good enough with them that i could do a majority of the maintenance on them and what not. Thanks!!

[dandyme]

look at this

[Scotty58]

i have seen that book on the barnes and noble website. only problem is the nearest barnes and noble to me is an hour away. ill have to read some of that on here. haha be nice to sit here and read the whole thing for free but i just cant sit at computer that long and read.

[Phisher]

Check with your local Trane office. They usually have classes for their customers. Ask the Trane technicians questions when they are on site. Most importantly be patient and don't get frustrated. It takes years to learn. Read the document dandyme posted.

[ascj]

Happy reading!

[Scotty58]

thanks for the advice and the articles guys! hell, keep em coming if anyone has anything different! haha ill spend my whole weekend reading if i have to.

[ascj]

thanks for the advice and the articles guys! hell, keep em coming if anyone has anything different! haha ill spend my whole weekend reading if i have to.

I would also get the exact model numbers off the chillers that you currently work on. So maybe some one on here can send ya the IOM's. Nothing like learning on what you get to see.

[Dallas Duster]

i have seen that book on the barnes and noble website. only problem is the nearest barnes and noble to me is an hour away. ill have to read some of that on here. haha be nice to sit here and read the whole thing for free but i just cant sit at computer that long and read.

Just print it off then.

[fbcit]

keep em coming if anyone has anything different! haha ill spend my whole weekend reading if i have to.

Here are a couple that I have found to be a big help.

[Russ57]

I doubt you will be asked to actually fix a chiller. Most hospitals don't want the maintenance guys tearing down units.

Mostly you need to know what a chiller requires in order to be able to start. You need to prove flow through evaporator and condenser. This is usually done with differential pressure switches. They are connected to the chill water and condenser water lines with tubing. Often they will stop up where the nipples screw into the larger piping. Next you need to prove the chiller is unloaded. You should be able to see a mod motor that moves the vanes. Depending on your chiller the linkage may make a limit switch or it might be a little more complicated. Take a look and see if you can find the parts. Ask your Trane tech. Sometimes the limit switch pulls in a relay that can go bad.

Then you have the regular maintenance items like brushing the tubes. Learn how to determine the "approach" as it will give you an idea of how clean the tubes are and what is normal for your machine. The importance of water treatment can't be over stated. Ideally you would want to know how to do your own testing.

More important is to understand that the chiller is part of a system. You have the chill water pumps, AHU's, and the flow rates through them. Neglecting proper flow rates and heat gain from dirty coils and improper installation and balancing will compromise things. Same thing on the cooling tower side. Something as simple as a float valve hanging up, dumping water out of the tower, will greatly affect water chemistry. A couple/few days of that is all it might take to start scale formation. Then efficancy goes to crap in a hurry.

Learn to catch problems early before they become a problem. Learn how all the parts work together.

[Shockwave]

I am also new to chillers but have a question regarding the differential pressure switches and how they operate. I am having a hard time beating into my head on there operation..

We currently have one installed on the suction/discharge side of our pumps. The switch was installed to prove flow and send it to the BMS in house system. I was looking at it yesterday and it is currently set for 60 cut in, 20 cut out(shouldn't that be the opposite??!?)

Our in house system runs usually between 85/90 psi, is the switch just opening closing when above 60 and below 20?


It's a penn p74 if that helps at all..

That'd for any help!

[KnewYork]

The switch was installed to prove flow and send it to the BMS in house system. I was looking at it yesterday and it is currently set for 60 cut in, 20 cut out(shouldn't that be the opposite??!?)

No, it's correct as stated. Once the pressure reaches 60 PSIG the switch closes proving flow. If the pressure drops below 20 PSIG then the switch opens telling the BAS that there is no flow (or insufficient flow). Usually a flow protection device is wired directly to the chiller control pane.l (So the BAS isn't responsible for shutting the chiller down.)

[Shockwave]

No, it's correct as stated. Once the pressure reaches 60 PSIG the switch closes proving flow. If the pressure drops below 20 PSIG then the switch opens telling the BAS that there is no flow (or insufficient flow). Usually a flow protection device is wired directly to the chiller control pane.l (So the BAS isn't responsible for shutting the chiller down.)

Thanks!, the wording on it just wasnt making sense to me...

So on initial flow it needs to make 60psig mininum or whatever the cut in is set at
And then it will open when the pressure drops below 20psig..

Cut in = High Side
Cut Out = Low Side

My additional thought at first was when it drops below 20psig and cuts out(alarms) the suction pressure would start to rise again after if the system is completely down. I imagine when setting your cut in(60psig) set point, that it must be higher than what your system will equalize at then? The guy thats been here about 30yrs doing HVAC was here when the guy set it up, he said they had to set it a few times before the tech was happy. He cant remember what it was, but i imagine they were looking for the pressure the system equalizes at?

Thanks again!