trane voyager rtu (won't economize)

[ctdl2003]

Have a Trane rtu model: YCD120C3LGAC. The unit will run a/c rather than economizer on a 33 degree day. Put the unit in the test mode and it economizes fine. Unit is connected to a ccp panel down below and controls 7 vav's. Connect computer to ccp and it says it's ok to economize and 33 outside. Also says cool 1 on and condensor fan on. Ohmed outdoor sensor and ok. Tryed to swap out ucp and uem with rtu next to it which works and still nothing.

[jayguy]

when you start getting into BAS...i start getting out! they can do whatever they want for whatever reason.

"OK to economize" does not mean that you should be economizing. it simply means that the outdoor air conditions are right to economize if the unit/BAS want to.

you may have duct static issues or building pressurization issues that the voyager does not even monitor. do you monitor any of these conditions?

good luck.

[busterboo1]

simple question... but most the time it is the simple things that get us...

did you check the compressor lock-out switch... and is it reading correct

outdoor temp?? may not be locking out the compressor/s.. ok to

economize simple means .. conditions are correct just as the other tech replied

[cxagent]

I thought Ok to economize meant the user had said it was OK, not conditions were right.

What kind of econmizer control is this? It could be Dry bulb (OA temp only) or enthalpy (OA temp and humidity) or differential enthalpy (return and OA temp and enthalpy). If it is dry bulb only, then the OA temp sensor or controller is bad. On that unit I think the controller is under the removable plate on the OA hood. If it is enthalpy control then OA temp or OA humidity sensor or controller is bad. And so on. If you can read OA temp and humidity from control panel you can tell what is bad. Or you can change parts with other unit until you find it.

Trane had a book on all of their electronics for that unit. At one time you could download it from the internet. Maybe somebody still has a link. I think it was call Trane's red book or Trane's black book.

[makinmoney]

I would also check to OA Temp Sensor, it's located in the cond section of the unit. In the test mode the Board doesn't look at sensor for operational purposes it just goes thru the different sequences.

[mike grabowski]

I have found the mixed air temp sensor's to be ok at regular room temps but when exposed to low temps it had no resistance.

[ctdl2003]

checked the outdoor air sensor and was ok as stated above. checked ohms to chart. What are you talking about with a compressor lockout switch? ccp should shut off compressors and run economizer unless DA isn't satisfactory. The static pressure is controlled by the bypass damper. How can duct static cause the unit not to economize? Static reads fine on the computer.

[whitepoundog]

Is the sensor wired correctly? And like makinmoney said check your OA sensor in the cond section and make sure it is correct.

[jayguy]

How can duct static cause the unit not to economize?

i do not see how it would either, but that was just an example of what the BAS may or may not be doing. the bas may be doing a lot more controlling than you think. i know that on some units, the Trane BAS can see more of what is going on internally, in the programming and such, more than we can standing at the unit!

and just because they say that it is ok to economize on the screen does not mean that they are telling the UCP that it is ok to economize.

sometimes cycling power allows the BAS to properly communicate with the voyager. i just had a voyager that the zone sensor checked out perfect...unit was running fine...but the BAS in Seattle could not see the zone sensor...they could see everything else...just not the zone sensor. cycled power and all turned out well.

if all of your sensors check out then call in a BAS person...i would. you would be amazed at how, after they have left, everything starts working fine.

good luck.

[mustardman]

Jay Guy was that problem you were having at a Costco by chance.

[jayguy]

Jay Guy was that problem you were having at a Costco by chance.

who is this? you spyin' on me? :)

[mustardman]

no but your equipment description and your reference to Seattle lead me to believe we are employed by one and the same. How many photo cells have you had to change lately I am at two in a month

[jayguy]

no but your equipment description and your reference to Seattle lead me to believe we are employed by one and the same. How many photo cells have you had to change lately I am at two in a month

no photo cells...not my usual account. i was thinking...i knew that they had cameras everywhere...but the roof too!?!?

my favorite part (not) is when it snows on the tin roof and then melts a little...don't need no snow board...skiing all the way to the rtu!!

good luck.

[mustardman]

I hear you with the tin roof I usually grab an apprentice to help with the filters and if he falls first he has to buy lunch. :D

[Yipikia]

Keep in mind that if you are using a Trane Stat you are dealing with a fully integrated economizer. If the space temp rises over setpoint to fast it might begin to economize then see the discharge air temp fall, which will close the economizer to maintain 55F DAT. But the compressors will continue to run to satisfy the cooling demand. If your dealing with a Micro-Control you will want to get the micro-manual.

[Tech Rob]

You can change the dry-bulb setpoint with the dipswitches on the UEM. Factory setting is 60* F. Enthalpy control of the economizer isn't standard.

UEM Economizers are designed to maintain a 50-55* supply air temperature. If the outside air temp is below 60* and the supply air temperature is 55-60*, and the fan is running, the economizer will open and close to to meet the supply air temperature setpoint of 50-55*

[tjc76]

check your economizer module for moisture damage. voyagers are famous for this. check all pin connectors for corrosion

[ctdl2003]

today had to do my pm and had some time to check into my economizer problem and found out what the problem was and thought i would share it with you all. On the uem I found 2 sets of black wires going to molex plugs. 1 for the sas and 1 for the exhaust fan relay. The sas was connected to j-6 xfc and the xfc was connected to j2 sas.

[macdaddy]

Maybe this will help...

1.3) Symptom:
Rooftop packaged units with ReliaTel Controls, with an economizer connected to a CCP unit.may run the compressor(s) when the unit should just be economizing. This may not be readily noticed unless the compressors are running at lower outside air temperatures. This is more likely to occur in areas where there are higher demands for economizing.
Solution: Remove and replace RTRM module

2.1) Symptom:

Economizer is enabled, but never opens 100% to allow compressors to run.
Solution: Replace ECA assembly, part number MOD01453.

https://www.comfortsite.com/Resources/Literature/pdf/RTSVB21AEN_0205.pdf

This next link is a must have if you service voyager
https://www.comfortsite.com/Resources/Literature/pdf/22770604_1099.pdf

[duke of earl]

I would see if there is a way that you can give local control to the rooftop for economizing instead of at the ccp. I'm not sure if you can but would check. If you can and economizer works than you can start looking at ccp for setup issues.