PDA

View Full Version : Trane 15 ton RTU


anellohvac
04-20-2005, 10:22 PM
I am having trouble with a 15 ton Trane gas fired RTU. Changed both compressors, contactors and coils were changed less then 1 year ago. Unit keeps tripping the circuit breaker on the transformer when 2 compressors are enabled. Any Suggestions Would Be a Great Help.
fixerup
04-20-2005, 10:25 PM
What is you amperage on your control circuit?
anellohvac
04-20-2005, 10:29 PM
I don't know that as of yet. One of my guys were there today again. I'll be going their in the morning. I do know that it has a 75 VA transformer.
seaboard
04-20-2005, 10:31 PM
If it's a 208/230 unit make sure the transformer is connected to the right voltage.
anellohvac
04-20-2005, 10:33 PM
We did that today and it's correct.
rtu
04-20-2005, 10:36 PM
possibly a shorted contactor coil?
anellohvac
04-20-2005, 10:37 PM
Furnas contactors were installed by a previous contractor less then 12 months ago.
joey791
04-20-2005, 10:37 PM
Long shot suggestion but it ate our lunch on one of these so giving it to you

Has any upgrade been done to the fire system or any other system that ties in to your unit.

We had a 15ton Trane that ran fine for over a year but then it started eating contactors, we went up to a 100VA transformer and still would eat contactors or trip.

Long story short, we found the fire alarm system was breaking R under the unit and above the ceiling, the fire alarm guys were nice enough to use about 60 foot of wire for a 10 foot run, all coiled up above the ceiling.
anellohvac
04-20-2005, 10:44 PM
Thats a mouth-full!!!

I will look into that. I just recently took this acoount over. I'll check into this. Thanks
love to fish
04-21-2005, 06:56 AM
there were some units that the pressure switches were rubbing on the door,and the wires were shorting. good luck
top mechanic
04-21-2005, 07:26 AM
There was a run of bad contactor coils, that Furnas ddid not admit to because they were being bought out by abother company, try another manufacturer,had the same problem, it is the contactor.
jtricor
04-21-2005, 07:32 AM
We had the same problem many years ago, found out it was in the economizer motor
chill factor
04-21-2005, 08:45 PM
Does your control fuse trip when second stage is trying to energize?

Or do the both stages actually run?

Does the fuse trip when you are there?

I would fuse each relay and contactor also the economizer controls individually to find out whats taking out your control fuse!