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  1. #1
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    RTAC won't start

    Had a co-worker looking at a foursome of RTAC's last week in the cold weather the building guys were saying that 2 of them would not start . ( part of their freeze protection scheme) the 2 chillers that would not start due to run inhibited, saturated condenser temperature below 25 degrees. So he called Trane tech support and told him that was the case live with it. Btw the units don't have low ambient. The Trane tech support guy would not elaborate on the reasoning as to what damage this would cause . Does anyone else know the reason for this?
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  2. #2
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    The RTAC has a pressure differential driven lubrication system. In cold weather w/ R134a it's difficult to build enough condenser pressure to drive oil into the compressor. High risk of compressor failure. Low ambient units have a variable speed condenser fan and will start down to 0F.

  3. #3
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    Are you asking about why the Trane tech support guy wouldn't elaborate or why the unit wouldn't start and what damage could be done?

  4. #4
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    Quote Originally Posted by zw17 View Post
    Are you asking about why the Trane tech support guy wouldn't elaborate or why the unit wouldn't start and what damage could be done?
    I had a feeling why it's not good but why wouldn't he say.
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  5. #5
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    25 degrees ???
    Better hope you have some glycol in them and the pumps are interlocked to the chiller as per the IOM ??
    If they dont have the low ambient option then your SOL !!!!!!!!!!
    Your customer didnt pay for low ambient and they aint gonna run without it . You could get them running if you really want to but be prepared to replace compressors and then you have to explain why they scambled to your customer !!!!!
    The toy chest is officially full ... I got a new toy..... 2007 Aston Martin V8 Vantage
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  6. #6
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    Trane has already signed off on the pump / isolation valve control years ago there is no glycol. Not per the IOM. It has not been this cold down here in 7 years to test this algorithm I guess.
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  7. #7
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    Trane has already signed off on the pump / isolation valve control years ago

    The latest IOM I have still states that the chiller has to control the pump or catastophic evaporater failure could occur ????
    The toy chest is officially full ... I got a new toy..... 2007 Aston Martin V8 Vantage
    You bend em" I"ll mend em" !!!!!!!
    I"m not a service tech.. I"m a thermodynamic transfer analyst & strategic system sustainability specialist
    Best Austin Healey In Show twice in 2013 .....All those hrs paid off .

  8. #8
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    Quote Originally Posted by graham View Post
    Trane has already signed off on the pump / isolation valve control years ago

    The latest IOM I have still states that the chiller has to control the pump or catastophic evaporater failure could occur ????
    I'm picking up what your throwing down but the customer has it in writing from Trane but don't worry Graham it made it out of the warranty period , btw I wasn't asking about freezing up the evaporator.
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  9. #9
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    don't worry Graham it made it out of the warranty period

    A frozen evaporator is a frozen evaporator and their aint no warranty that covers that !!!!!!!!!!!!!!!!!!!!!!!!!
    The toy chest is officially full ... I got a new toy..... 2007 Aston Martin V8 Vantage
    You bend em" I"ll mend em" !!!!!!!
    I"m not a service tech.. I"m a thermodynamic transfer analyst & strategic system sustainability specialist
    Best Austin Healey In Show twice in 2013 .....All those hrs paid off .

  10. #10
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    Mixing oil and fire with a big spoon.
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    generally speaking, you are going to trip off on low evap temp because you can't get any head pressure. the fans are going to be too agressive at start up. as for scrambling a compressor, probably not going to happen since you won't be running for long before a low evap temp trip.
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  11. #11
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    as for scrambling a compressor, probably not going to happen since you won't be running for long before a low evap temp trip.

    That all depends on weather someone is holding in the contactor with a big screwdriver trying to get it to run or not ?????
    The toy chest is officially full ... I got a new toy..... 2007 Aston Martin V8 Vantage
    You bend em" I"ll mend em" !!!!!!!
    I"m not a service tech.. I"m a thermodynamic transfer analyst & strategic system sustainability specialist
    Best Austin Healey In Show twice in 2013 .....All those hrs paid off .

  12. #12
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    Quote Originally Posted by graham View Post
    as for scrambling a compressor, probably not going to happen since you won't be running for long before a low evap temp trip.

    That all depends on weather someone is holding in the contactor with a big screwdriver trying to get it to run or not ?????
    As long as the 2 chillers that were running before the cold weather came in stay online Graham I promise you a big screw driver won't used to harm any compressors in this thread!!!!!!
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    It takes three people to do anything around here. Two do the work, one explains to the crowd of people who showed up when they seen smoke and flames.

  13. #13
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    Quote Originally Posted by thegoodlistener View Post
    Had a co-worker looking at a foursome of RTAC's last week in the cold weather the building guys were saying that 2 of them would not start . ( part of their freeze protection scheme) the 2 chillers that would not start due to run inhibited, saturated condenser temperature below 25 degrees. So he called Trane tech support and told him that was the case live with it. Btw the units don't have low ambient. The Trane tech support guy would not elaborate on the reasoning as to what damage this would cause . Does anyone else know the reason for this?
    If the customer want's them to run, have them pay Trane to install low ambient kits on them. They come out and install the VFDs on one fan per circuit, all of the wiring, and the modules for the VFDs. Then you can run down to 0 deg. F.

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