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  1. #14
    Join Date
    Feb 2014
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    Thread Starter
    Also related: The installer of the ice rink did not calculate head or size the brine pumps appropriately. The chiller barrel is designed for a maximum of 700 gallons per minute flow. The pumps were pushing nearly 1200 gpm. I corrected this problem with a variable frequency drive, and now run slightly below 700 gpm. Could this have damaged the gaskets or is the brine chamber isolated from the refrigerant lines?

  2. #15
    Join Date
    Jun 2003
    Location
    Madison, WI/Cape Coral, FL
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    If you trap air in the condenser, the air is uncondensable and will show high head. With high head from the refrigerant, you will have high heat. Trapped air is uncondensible and will have a hot condenser. Shut the system down and bled at the compressor discharge. This will bled the trapped air. Any leaks on the low side could suck air into the system is the low side is negative.
    Regards TB
    Bear Rules: Keep our home <50% RH summer, controls mites/mold and very comfortable.
    Provide 60-100 cfm of fresh air when occupied to purge indoor pollutants and keep window dry during cold weather. T-stat setup/setback +8 hrs. saves energy
    Use +Merv 10 air filter. -Don't forget the "Golden Rule"

  3. #16
    Join Date
    Jan 2011
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    Quote Originally Posted by crashputer View Post
    Also related: The installer of the ice rink did not calculate head or size the brine pumps appropriately. The chiller barrel is designed for a maximum of 700 gallons per minute flow. The pumps were pushing nearly 1200 gpm. I corrected this problem with a variable frequency drive, and now run slightly below 700 gpm. Could this have damaged the gaskets or is the brine chamber isolated from the refrigerant lines?
    They are separate. Yours is a DX chiller where the refrigerant passes through the tubes and the water travels on the outside of the tubes trough a series of baffles.

    Fixing the gaskets between circuits is a major PITA.

  4. #17
    Join Date
    Jan 2011
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    Quote Originally Posted by teddy bear View Post
    If you trap air in the condenser, the air is uncondensable and will show high head. With high head from the refrigerant, you will have high heat. Trapped air is uncondensible and will have a hot condenser. Shut the system down and bled at the compressor discharge. This will bled the trapped air. Any leaks on the low side could suck air into the system is the low side is negative.
    Regards TB
    Bleed to atmosphere? Pretty sure that's illegal. The compressor is nowhere near the high point of the system, which is where any non-condensibles would tend to accumulate.

    How did the non-condensibles get in there?

  5. #18
    Join Date
    Feb 2014
    Posts
    9
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    Thread Starter
    Re: bleeding through the gasket... would there be any chance of introducing brine (in this case, 35% propylene glycol solution) into the refrigerant system? I spoke to a person at my vendor's office (not the technician, he was out of the office, but a person who has dealt with this scenario) and he mentioned the possibility to me. So far I have no evidence of this.

    As far as non-condensables in the condenser, would that suddenly from nowhere cause near-immediate overload? And as long as my compressor has been offline, would it not be a detectable refrigerant leak instead of suction?

  6. #19
    Join Date
    Feb 2014
    Location
    Atlanta
    Posts
    228
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    What saturated suction does the machine operate at? I have 2 06CC Compound reciprocating compressors that use 507 to chill a thermal fluid Syltherm to -57 C. The low side operates in a vacuum even though it is a high pressure HFC refrigerant. Suction normally runs 1-2 inches and the head around 200. We had a king valve pulling air in on the low side causing a similar issue. However if non condensible gases are expected just pull the charge and repair. Do you know if you have a discharge check valve??

  7. #20
    Join Date
    Jun 2013
    Location
    Mechanicsburg, Pa
    Posts
    31
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    sounds like bad txv

  8. #21
    Join Date
    Oct 2001
    Posts
    6,966
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    is the compressor starting up loaded...are the condenser fans ambient from outdoor air sensing...or direct pressure sensing off the LL or discharge?
    "when in doubt...jump it out" http://www.youtube.com/watch?v=U1qEZHhJubY

  9. #22
    Join Date
    Mar 2011
    Location
    Nw.Connecticut
    Posts
    307
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    Quote Originally Posted by Nuclrchiller View Post
    Also, make sure that a free wheeling condenser fan, rotating backwards, hasn't been mistaken as running normally. I've seen that mistake made more than once. Even by people who should know better...
    Looking over my shoulder ?been there
    , bring coffee next time .

  10. #23
    Join Date
    Mar 2011
    Location
    Nw.Connecticut
    Posts
    307
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    Only 1 of 4 is bad ? That would tend to rule out gasket . No one mentioned filter drier. Does it run at neg. pressure ? I have not seen that info . One comp. damaged by power trouble, any others effected ?

  11. #24
    Join Date
    Jun 2003
    Location
    Madison, WI/Cape Coral, FL
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    Quote Originally Posted by KnewYork View Post
    Bleed to atmosphere? Pretty sure that's illegal. The compressor is nowhere near the high point of the system, which is where any non-condensibles would tend to accumulate.

    How did the non-condensibles get in there?
    Air is not condensable and accumulates in the condenser, not the high spot in the system. Hook you recovery to the condenser at the compressor discharge and watch your gauge, if air loaded, you will high head in your recovery system.
    Just trying to help.
    Regards TB
    Bear Rules: Keep our home <50% RH summer, controls mites/mold and very comfortable.
    Provide 60-100 cfm of fresh air when occupied to purge indoor pollutants and keep window dry during cold weather. T-stat setup/setback +8 hrs. saves energy
    Use +Merv 10 air filter. -Don't forget the "Golden Rule"

  12. #25
    Join Date
    Feb 2013
    Location
    South Arkansas
    Posts
    29
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    just asking/ could you not hook up gauge to system and check p/t chart to see if pressure and temp match for type of refrigerant to check for non condensenables(sic). system would have to have been down to get accurate check. someone let me know if that is not a viable method of checking.

  13. #26
    Join Date
    Aug 2006
    Posts
    3,328
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    I would be extremely suspicious of a leak by on your liquid line solenoid or 0% open EXV. If you have a Rotary type compressor, "Non Piston," remember that any liquid that goes in the suction is going to be expanded around 1500 times when it comes out of the discharge. There will be no head loss as with a recip. Pump the circuit down with king valve closed, wait till the circuit has settled in off cycle and slowly open the king valve to see if your suction pressures start to creep up.

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