CVHE Sensors reversed?

[duke of earl]

Have 2 CVHE machines and Tracer Summit V. 17. Lately when viewing the chiller plant graphic, the chilled water sensors seem to have been reversed. Same with the condenser water sensors. I confirmed these readings in the UCP2 and they are definitely backwards. Has anyone seen this before or is someone screwing with these machines when I'm not looking?

[jimbob73]

Is this suppose to be some kind of trick question? I say if the machine is running and leaving chilled water is warmer then entering by a few degrees, or condenser leaving is colder then entering by a few degrees, The sensors have been swapped at the piping or in the control panel. I have seen this many times, But only on new start-ups.

[kwillmech]

Hmmm... sounds like the reversing valve is stuck again.

[mallron]

I have only seen this once and it was on a rental CVHE. How can the machine run for any length of time with the sensors reversed?

-JB

[duke of earl]

The chiller runs but is confused and the inlet guide veins are hunting as a result. I have reversed the sensors on a couple of occasions to make them read correct but this past week the readings were backwards on one of the machines and once again I had to reverse them again. I think someone is intentionally doing this as a bad joke. Any thoughts?

[jimbob73]

Bad joke or possibly bad sensors. I would verify sensors are in correct locations and apply a tamper seal on them by using paint marker and applying paint on all pieces that can be taken apart. This can also be done in the panel where sensors terminate at green plug and module. If problem happens again, check to see if paint seal is broken. If there was no evidence of tampering, Check out the sensors, Perhaps moisture is getting into sensor and affecting resistance value of thermistor or compression fitting for sensor was tightend with big friggin wrenches.

[StillKicking]

We use Hot Pink fingernail polish as tamper proof. Most likely sensor(s) are bad, since running the chiller backwards won't make hot water (for very long).

[slimwoodie]

can the joker, for what he's doing to your chiller ....

[duke of earl]

Did the tamper marking in hopes of nailing this down on Friday. I replaced one set of cw sensors on one of the machines. The other chiller was the problem on Friday so maybe the sensors are failing.I will follow up and let you guys know. Thanks!

[lipsoffurry]

Are you getting any carryover? Has either of the machines failed for this issue?

[duke of earl]

No failures yet. We are on site every day watching so when it happens we reverse the sensors and no problem.

[mallron]

I still don't understand how a chiller can run with the entering and leaving chill water sensors reversed. If the the entering chill water sensor is reporting its temp to the control module as leaving water temp, then the chiller would load to 100% and stay there until someone lowered the setpoint to the same value as entering water temp or switched the sensors back to their correct positions.

What happens when these chillers start?

-JB

[jayguy]

are the temp sensors actually showing reverse temps? or is it controlling to a different temp sensor? (i might be able to make that sound more confusing )

if it is an ice building machine, the unit runs at full load until the ENTERING water (glycol) temp sensor is satisfied. just a thought.

i can not think of any reason to have the temp sensors act different AND be a normal reason for it (a failed board, withstanding of course)

also, i do not know your application, but you are not getting a reverse flow condition are you? (i do not know why someone would do this, but i have seen some weird sh!@ before). measure the pressure drop to verify that flow is correct. maybe the UCP2 is correct and flow is goofing up. a properly working flow switch would prove this as well.