View Full Version : Trane Varitrac Question
04-03-2008, 05:35 AM
We recently took over a building with many complaints from space temps too warm or cold. 2ea 15 ton, 2ea 12 ton, 1 5 ton for basement. The system has the CCP touchscreens. This is the first I have seen of these and Trane support in my area is non existant. My basement unit (5 ton) will not start the supply fan. Screen shows communication with unit up and yes. Diagnostics indicate 2 problems. Low pressure safety open. And Duct pressure sense fail. The odd thing is it still trys to run heat and is cycling the burner off limit. I tried rebooting off the screen and makes no difference. Found this problem right at the end of the day and suspect I will find issues with other units as I service them. I was not able to locate any troubleshooting info on this system. The refrigeration circuit is not my main concern right now, just troubleshooting the controls and getting the fan back on line. I think it is set up as a CV with a changeover bypass. Anyone have any suggestions? The installing contractor does not want anything to do with the building. Too many service calls I think. I appreciate any input.---Rethy
04-03-2008, 10:40 PM
When you say Varitrac I guess you're referring to an AHU that serves VAV's? If so then the Duct pressure sense fail error probably indicates that the static pressure sensor normally located 2/3 the way down the duct is not working properly and the VFD or inlet vanes do not know what to do if this sensor fails. It may be programmed to remain off if there is a supply static sensor failure.
04-03-2008, 11:06 PM
varitrac changeover bypass will have a temp sensor/static pressure controller with ucm board
installed before the bypass duct.
04-03-2008, 11:37 PM
is this a variable speed rtu and does it have a remot keypad display in the control panel or does it just have the vfd
04-04-2008, 06:15 PM
Do not assume its the controls. All the varitrac is telling you is that it did not sense airflow. Does it show the fan is on ? Does the unit have a UCM ? or does the varitrac panel have an add-on board with relay outputs?
I would start with the unit and see if the fan runs in test mode.
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