New to chillers
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!!
It`s better to be silent and thought the fool; than speak and remove all doubt.
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.
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.
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.
Originally Posted by Scotty58
Just print it off then.
It takes three people to do anything around here. Two do the work, one explains to the crowd of people who showed up when they seen smoke and flames.
you could always print it?
Originally Posted by Scotty58
I WILL SELL WORK,GENERATE BUSINESS, GO GET NEW CUSTOMERS!
YOU SHUT THE HELL UP AND QUIT RUNNING YOUR MOUTH!
The most important thing you need to know about chillers is, that water freezes at 32°F and static water freezes far quicker then anything else. Therefore never charge a water chiller with liquid refrigerant at saturation temperature below that magic point, never do that with static water on cooler and condenser and never bypass the flow protection device (of course the HP switch as well).
"Quality exists, when the price is long forgotten."
remember that dp switches on pumps prove that the pump is RUNNING. they do not prove that the pump is FLOWING. i have been to many jobs where the bas techs use dp switches to prove the pump is flowing (which is incorrect) and then start the chiller. i mostly don't like them on anything (pumps or chillers) because the piping to the switch does not have any flow in them and over time, crud fills up the piping making the switch fail.
a fun example with dp switches on pumps: close 1 isolation valve to the chiller (with the chiller off) then manually start the chilled water pump...the switch will make...do this in front of the bas tech and ask them to explain why this is happening. 95% of the bas techs will say that the switch has failed and needs replaced!
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Don't need a phone at all
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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.
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!
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.)
Originally Posted by Shockwave