ReplyWas it a wye delta starter? Just FYI I would honestly NEVER EVER pumpdown a screw compressor .
Professional Member*
I pumped the unit down. i did let the crankcase go into a vacuum for a short period. Shut down unit and let the 30# cylindar empty into system via the liquid charging port on the bottom.
when compressor started, its like a lagging almost low voltage sound\drone for about 3 sec and then takes off normal.
Has anyone else experienced this?
then next 3 starts thru out the morning all sounded normal.
This happened on 2 diffent chillers today as i completed a leak check and repair on each. Systems are tight, 550 microns via my new JB digital vac guage, no leaks now
If you cant fix it right, try again.
Professional Member*
Was it a wye delta starter? Just FYI I would honestly NEVER EVER pumpdown a screw compressor .
Professional Member
Like thegoodlistener said do not ever pump a screw down into a vac. or a scroll. The slide valve could have moved to the loaded position from the large delta p when you pumped it down into a vac. Pump it down to 40 psig and let your recovery machine do the rest. Just to be on the safeside.Originally Posted by toptech
Professional Member*
It wasn't intenional, I normally close off the liquid valve and stop the compressor just shy of vac, it got away from me.
Ive only had to add refrigerant twice on these chillers. Whats the best way to charge?
Thanks
XL Start too
If you cant fix it right, try again.
Professional Member
I never charge in the liquid line with liquid, unless I have pulled all of the gas out of the system and have saturation temp. well above freezing(if it's a chiller) with vapor. If you have enough gas in system to keep it from going out on low pressure, charge in comp. suction, on large compressors liquid through a 1/4" hose isn't going to hurt anthing as long as comp. is running.
Professional Member
Charge how top off or full charge? From an evacuated system add vapor until ABOVE freezing, then flip it over and use liquid. Use charging valve out of EXV into evap. Flooded evap, you can top off charge same way.
Sic Semper Tyrannis.
Professional Member*
Thats what I has going to do and the carrier book said to use the liquid charging port! let me find the page, oops!
3. Add 5 lb (2.3 kg) of liquid charge into the cooler using
the 1⁄4-in. Schrader-type fitting located on the tube entering
the bottom of the cooler. This fitting is located between
the Electronic Expansion Valve (EXV) (size 076-
146 units), or the economizer (size 161-271 units) and
the cooler.
Sheet, i read what I thought it said not actually what it said! I hate when that happens.
Thats what I get for rushing, thanks guys for helping me think.
If you cant fix it right, try again.
Professional Member*
This was a top off charge, i had water running thru the barrel. I got it half right
If you cant fix it right, try again.
Professional Member
I never, repeat never, rely on having water flow through barrel when charging with liquid. Always looking look at saturation temp. make sure it's well above freezing. Because what if one, just one, tube is stopped up.
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Step 7 — Refrigerant Charge
NOTE: The liquid charging method is recommended for
complete charging or when additional charge is required.
When charging, circulate water through the condenser and
cooler at all times to prevent freezing. Freezing damage is
considered abuse and may void the Carrier warranty.
True, but I did follow those instuctions!
If you cant fix it right, try again.
Professional Member
Totaly agree, always vapor until at least 40F sat temp on water, possibly lower on glycol.
To much work with too little time!!!!
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perk, wow just one tube can cause serious problems huh., i understand that want to run water through barrols and want to charge w vapor until saturation is about 40*, can u explain y just one tube can cause such a problem? thanks
no signatureblast'em man blast'em
!!!KILL THE TERRORIST!!!
Professional Member
If you have a tube which is blocked you now have no flow through that tube. That is why it's recommended to charge with vapor until above 40* saturation temp, so that you know there won't be any chance of freezing the water in said blocked tube.
Professional Member*
and that there son is how a tube bust.,.,lol
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!!!KILL THE TERRORIST!!!
Professional Member
Break out the heat gun and the patience. Don't let the customer or the boss push you cause replacing tubes sucks!
Professional Member
Git-r-done!!
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rerplacing tube., h***., flooded machine
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!!!KILL THE TERRORIST!!!
Regular Guest
I know this is a huge fear in the industry. But,you have to take a close look at what your working on. For Instance where is the liquid port located? How far away from the tubes is it? You are not going to freeze a tube on a RTHD by dumping liquid into the evap liquid port at the bottom of the barrel. And I dont see a reason to shutdown or pumpdown a 30h (However I am not that familiar with this machine). Refrigerant is going to migrate to the coldest place so why not use this same port for adding ref. Then you dont risk carry over(slugging) or shutting down the machine. You also dont need water running through the barrel When removing refrigerant once you get all refrigerant isolated into the evap/cond. when pulling off the bottom. That way with multiple chiller plants you are not mixing water for very long and therefore not loosing the temp/humidity control of the building. Now If we are talking brazed plate and frame heat exchangers you better have water running at all times. And have fun adding refrigerant to these. They are a pain.
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