Using a printer module as a diagnostic tool on UCP2

[ChillerWisperer]

Has anyone used an optional printer module as a dignostic tool on a UCP2 chiller? I remember it being talked about at the LaCrosse and Pueblo factory courses. You could temporarily hook up the printer module on a chiller that was having nuisance trips and it would save the last 15 minutes of operating parameters in it's buffer prior to the diagnostic, which you could then print out. Just wondering how well it works and can it be easily moved from chiller to chiller and is it easy to set up? Thanks

[chillrdude]

It is very easy to setup, the only draw back is that you need a different module for each type of machine. I carry 3 different modules in my portable printer bag, 1 for centra-vacs, 1 for absorbers and 1 for water cooled screws. It really comes in handy when doing inspections and logs on absorbers. The print on diagnostic feature has come in handy as well.

[MKnyc]

what kind of nuisance trips are you getting?

[ChillerWisperer]

what kind of nuisance trips are you getting?

Low evap temp on a RTHB150. It starts and runs fine throughout the day and then trips in the evening, but only sometimes. We have adjusted the scheduling of the air handlers, thinking low load at end of the day near scheduled shut down. It's in a law office where some of the occupants work late and have the ability to override the scheduling for a single air handler, which causes the chiller to short cycle. The BAS doesn't have the ability to trend and I don't have any way of finding out if it's on the nights that an AHU has been over ridden that the chiller trips. When it does, the BAS automatically switches to the lag chiller and the diagnostic isn't found for several days sometimes. Only the one chiller does it and they are same model. I have checked oil and refrig. charge, sensor operation, exv and stepper module, etc. The evap water flow is a little above submittal delta P and the DP switch is brand new and properly adjusted. The setpoint is 44 and it usually runs about a 2.5 deg approach. I have never seen the sat refrig temp below 41 during running operation at full load. I have gone through the field start up and machine config menus and made sure all of settings conform to the factory settings. All of the settings and running parameters on both machines are identical, but only the one chiller trips.

The one thing I don't like about the setup is that there are two towers and condenser pumps, but the chillers share a common condenser header. The condenser water flow is split between the active and idle chillers, robbing the running chiller of half its' flow and pushing the cond delta T up to 13 or 14 deg at full load. I have noticed the discharge superheat hunting, causing the EXV to hunt also. I don't know if this could be a contributing factor in the low evep trip, but the way the machines are piped, the chiller with the problem gets a lower condenser flow than the other machine. When I do the inspection and log the chillers, I do it with the idle chiller condenser flow valved off. I have been hounding the owners for the last seven months (when I first took over the account) for the need to automate the condenser valves, but they claim they can't afford it.

Anyway, I was thinking of installing the printer module so I could capture the operating conditions at diagnostic shutdown. Also, anyone have the Trane MOD#'s for the RTHB and CVHE printer modules? I didn't realize there was a difference...learn something new everyday : )

[CaptJackSparrow]

Wisper, you probably know to check the charge by exv position at 40 to 60pct at 100 pct load. Also the exv min steps was increased on early machines. Water flow affects discharge superheat allot also. If you have two way valves that could be an issue. Overcharge will cause the exv to hunt also. Had one fith a restricted refrig filter also. You can check for subcooling with your gauge and ucp sat cond temp. They should be close to each other.Fat fingers and I phones don't mix.

[chillrdude]

Well I went to get you the part #s off of my modules and found that I have apparently left my printer module on a chiller, luckily I know where it is, I will get it this week and post the part # for the centra-vac.

Absorber x13650573-03
Screws x13650540-02

[ChillerWisperer]

Wisper, you probably know to check the charge by exv position at 40 to 60pct at 100 pct load.
I locked the EXV at 60% through the service tools menu to check the charge by monitoring the discharge superheat vs. target per RTHB-SB-6 and it stayed within 3 to 4 deg when I had full cond flow through the running chiller. With the flow split like it is normally, I had a lot more disch suprht hunting.

Also the exv min steps was increased on early machines.
It's an '03 machine so it has the upgraded software mentioned in RTHB-SB-2. I checked the EXV min stop and it is set at 18% like the IOM calls for on a 150 ton machine.

Water flow affects discharge superheat allot also.
Cooler flow only? My chilled water flow is good when I'm seeing it, but I'll look into whether the ahu's have two or three way valves. I haven't done that yet. I'm seeing a disch suprht swing of 8 to 12 deg unless I divert full flow through the condenser.

If you have two way valves that could be an issue. Overcharge will cause the exv to hunt also. Had one fith a restricted refrig filter also. You can check for subcooling with your gauge and ucp sat cond temp.
Haven't checked subcooling yet either, but I'm pretty sure it's not overcharged.

They should be close to each other.Fat fingers and I phones don't mix.

Thanks for the input!

[ChillerWisperer]

Well I went to get you the part #s off of my modules and found that I have apparently left my printer module on a chiller, luckily I know where it is, I will get it this week and post the part # for the centra-vac.

Absorber x13650573-03
Screws x13650540-02

Thanks for the numbers! Makes life a lot easier when I'm talking to the parts guys. I had given them the serial and said I wanted a 1U7 mod for it. "But it doesn't have one in it"... "I know"...then it pretty much turned into a "who's on first" debacle.

[CaptJackSparrow]

The exv min steps is expessed in steps. Seems like 1780 steps but you will need to check iom.

I was refering to chill h2o flow change.

Were u at 100pct load when you locked the exv at 60?

You know half cond flow will drive disch superheat.

Top suspects would be those items plus cond h2o temp.

[chillrdude]

Found my missing printer module.

Centra-Vac x13650458-04

[r404a]

anyone have a model number of a serial printer that would work in this application? thanks

[double bogey]

IIRC its an Okidata320. Its a dot matrix.

[r404a]

thanks double bogey