Varitrane VPEF heat troubles
I have a varitrave vpef vav box with a ucm4.2 board. This is a 460v 3 phase unit. On a call for heat the blower will come on, make the air switch and and go to the contactor that beings on the heat strips. This is a single stage unit. The orange wire(com/grnd) is not making a ground so the contactor won't pull in. The back of the ucm board looks good, no burnt connections. I havn't had a ucm board go bad on me yet but could this be? I can jumper the orange to a ground and contactor pulls in and all is well till it's suppose to satisfy lol. Is there a way to test the ucm board?
Does the common wire go thru any switches? Or does it come straight from common on board to contactor? I have had a wire break that still read voltage thru it but, wouldn't pull in a relay because no amperage could go thru it.
The common goes strait from board to contactor. Check wire continuity and a new temp wire from board to contactor. So im thinking it's internal to the board.
The UCM breaks the common. Can you see the status of the heat output through software? Are you meeting the min heat flow setpoint?
Originally Posted by hvac69
I will check that tomorrow. It is connected to tracer software, set to thumb wheel control. I have not verified actual cfm output but i do know blower is running wide open and nada.
On another note. What do the dip switches control on the ucm board?
Originally Posted by Crazecodyk
The dip switches are for software addressing 1 through 64 and E-ware address 65 through 127
So if the dips 5&6 are in the on position that should be the tracer address for that unit?
The dip switches are a little tough to decipher, but here is a quick explanation.
Each switch represents a value in the binary number system such as 1, 2, 4, 8, 16, 32, 64, and 128.
Note: VAV UCM 4.2 only use 6 Switches
Summing the switches that are in the on position determines the address.
For example 1, 8, 32 are in the ON position = Address 41
NOTE: This is the actual UCM address and will not always be the actual Tracer address listed for Hardware.
This will be dependent on Comm such as Comm 3.
You are using comm 4 most likely but will need to check.
Trane Everyware Software:
Must Add 64 to the base total:
Example: 53 + 64 = 117
or: 1+0+4+0+16+32+64 = 117
or 1+4+16+32+64 =117
or: 53 UCM Address + 64 E-ware address = 117
As for the comm wire I see that they are on TB2-5 and TB2-6. I normally connect this to TB2-1 and TB2-2 and the daisy chain to TB2-3 and TB2-4. How ever there are others who connect the daisy chain to TB2-1 and TB2-2 as well. There is more than one way.
Your connection may work but needs to be verified that it is correct. As for the shield it must be connected with one another and tapped back so as not to touch any ground or the metal cabinet.
Have you set up the VAV's and verified that they are configured correctly.
What do you mean that you have it in the manual mode? Are you saying that you have overridden functions?
Hope this helps
Trouble shooting is not part of the repair........understand the symptoms and you will find a solution.
Ok. After looking at it today. Was able to bring it on via tracer system. I don't think the vav has been fully set up yet my the trane guys. So i've got it in manual mode till the rest of the construction finishes.
I've installed theses VAVs in the past but never set one up to run off tracer. I would like to learn more of that. I have books that i am slowly reading through to self teach me.
I was able to get into the tracer system ,click on the unit graphic, and overide the unit to come on(still unclear how i did this) they are haveing alot of communication issues with several of their units on several floors. Once all the construction is over, all the control guys are going to have to add all the new vavs to the system as well as troubleshoot the old ones as well. Wish i knew more about it. Will get there though