chiller's gone bad

[chillered]

this one i can't figure out. i have 2 -800 ton carrier 19xr. they have been running great all summer. but when i came in monday they both were surging to the point of triping out . they both have high condenser pressure. 110 to 120 psi. high condenser approach. 5-7 how can both of them be doing this at the same time . what are the chances that both have dirty tubes. i have 2 500 ton in the came building and they are running great . all ideas would be welcome . this is wearing me out

[chillered]

another not all the reading were when chiller is above 60 % . when it is below 60 no problems

[youngr51]

Condensing water flow problem?

[enart9591]

chillered, we need all the operational readings.

Chilled water temp in and out, and water pressure in and out.
Condenser water temp in and out, and water pressure in and out.
evap refrig pressure and temp
cond refrig pressure and liquid temp

[acjourneyman]

FLow!!!!!Strainers!!!!flow!!!!!

[hvac tim]

what are your cond. & evap. temps? try to raise the setpoint up by a couple of degrees. what refrig. are you using?

[chillered]

evap temp- 42.1
chw in -53.5
chw out-43
ref. press.-107.9
ref. temp-91.6
cdw in 81.9
cdw. out-89.1
% amps 64.7 %

these are some readings from a log sheet monday. carrier is coming to punch tubes tomorrow. i cleaned strainers today they looked good. i went back and looked at log sheets for last month and nothing really looks to have changed. i have a system that one 800 ton and a 500 ton should handle and im running 2- 500's and one 800. i had to bring on extra 500 ton to take load off of the 800 so it would run. the carrier techs came in monday and could not figure it out. all they did was reset all my surge protection settings which made it worse.

[enart9591]

Operational conditions look good.

2 degree condenser approach, 1 degree evap approach, tower water in and out below design, normal evap and condenser pressure.

Does your machine have movable diffuser plates? If so, I would suspect that that is where the problem is.

[chillered]

tell me more about plates. both machines are running bad.

[chiller mekanik]

You can contact RCD & they will tell you the design specs.
Most likely your cond approach is a little high if its already 2.5* @ 65% mtr crnt.
Are these 19XR or 19XRV?
Do you have HGBP?
Is it enabled?
What are your P1, P2, T1, T2 settings?

I would really like to see a log @ FLA.
When you get the design data make sure you get it all.
Delta P & Delta T for cooler & condenser.
Ref temp & ALL of the surge prevention setpoints.

To be clear, I'm not saying you should have to use the HGBP, but, the setpoints need to be entered correctly in order for the machine to initiate HGBP or limit capacity by holding the vanes or if it is a 19XRV speed the compressor up to create more lift.

[Shophound]

I'm down here in my plant right now (finally got permanent computer station in plant...yeah!). I was going over your chiller's numbers and comparing them to my one 220 ton 19XR that's on line right now. My condenser's running 1.2 approach at 87% motor amps with 79.6 degree tower water entering condenser. Delta P through condenser is 7.6 psi.

What I'm wondering about your setup is a few things: are the two 800 ton chillers on the same towers as the 500 ton machines? Are the 500 tonners also 19XR's?

The thing that caught my eye about your post is that you left your machines on Friday running great and returned on Monday to find two of them surging/misbehaving. That would make me think that something happened that is affecting both machines. If both machines share the same condenser water, and if the 500 ton machines use a separate tower or condenser water, I'm thinking something over the weekend fouled the 800 ton condenser water circuit...or the 500 ton machines are different makes and don't react to whatever change occured like the 19Xr's do.

You also mentioned not much has changed via your log history. Would that include these machines running with no problems at greater than 65% with the approach numbers you gave?

Please let us know what you find out. Since I also have these machines I'm wanting to know what happens to them, and learn.

[chillered]

carrier came down today and cleaned the tubes and presto everything is beutiful. i can't believe that they have gone bad that fast.

[jamcool]

Check your tower water treatment system

[chillered]

yes sir im on there butt now

[chiller mekanik]

I'm sure some will disagree with what I'm about to say but here goes.
I think the 19XR is a great machine & I have several of them under my care.
Out of all of the machines I work on, (which is a pretty good variety) the 19XR has the tightest envelope of any other machine in production.
I understand that the tighter that envelope is compared to design, the more efficient it is.
Clearly you have a water treatment issue that you have to stay on top of, I'm just saying that those machines are "surge happy" or the least forgiving around.

Also, the 19XR has enhanced tubes & the only way to clean them properly is with a tube brush machine that has reverse.
I know its a pain in the arss but you have to run the brush in clockwise, when you get to the end you have to stop, change directions (conter clockwise) & don't be in too much of a hurry.

[carriermechanic]

You just need to use a 3/4 brush on a 5/8 tube. As long as it is slime it should come out at a normal pace.

[Shophound]

...then one of mine must have the blues. :p

Late last week JCI came out to tweak on the Metasys ADS. While doing so we noticed we had lost comm with the NAE in the plant. So he reboots it. Problem with that was it loaded up the relinquish defaults for equipment to be online, knocking my lead chiller, pumps, and towers offline and bringing up the default leads. Shouldnt've been a problem other than a brief downtime in the plant but the lead tower was now one with a missing VFD...fannie no workee.

I didn't catch it right away until I looked at a graphic for the chilled water system and noticed my building supply and return chilled water temp were about equal. Thinking the plant had completely crashed, I ran down there only to find Chiller #1 online and running. How it was still running left me stunned. Tower #1 with no fan was just dumping water through the tower, supplying 95 degree water to the condenser, with 112 going out! The chiller was just sitting there at demand limit, churning away but not surging!

She was just starting to surge when I got the working towers back online and the supply water temp began dropping. It blew me away that at 95 CWST she wasn't already tripped out. We have good chemical treatment on all our loops, but that's the one chiller I haven't punched tubes on yet. Go figure.

[williamd]

I am running 2 of the 19xr's 800 ton usally we just need 1 to handle the load but on hot days like 95 degrees or hotter we need to run the second chiller.When we start it up condenser water loop is about 83 degrees the chiller will not load up due high lift yet looking at the lift its about 45 does the control panel look at other parameters besides just the lift or does it use different settings depending on how much the chiller is loaded.Also what brushes do you guys recommend for punching these tubes Thanks.

[carriermechanic]

Like I said before, several of us at the Dallas branch have been using 3/4 nylon brushes for 5/8 tubes. I know it is a little harder to push threw the tube, but it works a lot better. Especially when you have slime build up. You might need to adjust your P1 or P2 setting. You should not touch the T1 or T2 setting. You need to graph your pressure differential your temperature differential when this occurs and decide what changes you need to make. If the problems occur when the machine is unloaded then you need to change P1. If it happens when the chiller is loaded then adjust P2. I actually had a problem with a 19XL today with a pic 1. It was running with high lift while it was unloaded. So I adjusted the P1 setting and it went away.

[chiller mekanik]

Hey shophound, sounds a like you've got one or two that has a better impeller & condenser selection than most of the ones I tend to.

Williamd, carriermech is giving you some good advice.
Think about this: Its only "high lift" because you tell the controller that it is.
Find the "sweet spot" with those parameters & the machine should do pretty good for you.

[referteacher]

Tube brushes----Goodway ESGB-062 are the only way to go. They are the grey "Christmas Tree" brushes.
Like chiller mekanik says, you gotta reverse the brush rotation on the way out to get the crud out of the rifled grooves.

Adjust P1 & P2 but leave T1 & T2 alone....I disagree.Had an 19XR retrofit that was spec'd for 15 dgree chilled water delta with a two pass bundle. When installed and started the chilled water flow was actually 9 degree delta at full load. The surge prevention line was so flat it wouldn't load up at high load and it would surge and crash at low load. After logging all parameters over several days over all load conditions, I was able to plot actual surge line and configure the surge prevention accordingly. Had to change T2 to 9 degr. Also had to push P1 way down to minimum setting of 30 psi. Been running as sweet as you please for two years now.

I also try to use chilled water reset as often as customers will let me to keep the lift down as much as possible. Also pushing the tower temp down as much as you can will help to decrease the lift.

[carriermechanic]

It is ok for you to disagree. In MOST situations you should never change the T1 and T2 settings. There are times that you need to change it but those times are few and far between. I have started several 19XL's and 19XR's over the years. And there have only been a handle full of times when I had to change these settings to make the chiller run the way it should.

[steward]

I take care of several of these machines and the xr seems to be really touchy about the tubes being dirty. Seems to me if the chillers were running fine with clean tubes then don't touch the t1p1t2p2 settings.

[carriermechanic]

That is obvious but we are trying to help out William. You should not make any adjustments to those settings unless you know that everything else is the way factory requires. Changing these settings should be the last thing to change.