Mcquay Chiller

[Charnut]

Hello HVAC Tech's
I have been out of the field for a few years and in the next couple of weeks I might have the pleasure of changing out a large screw compressor on a Mcquay chiller. I think the compressor is around 75 hp. 480/3 R-22 grounded out. besides the normal clean up and suction line filters, Does anyone have any tips or know of anything special I will need to know or do for this change out. I have never done a screw compressor but have done 65hp trane compressors.
I thank you for any info you can give me.
Gary

[hvac_superman]

How long have you been out of the field and are you now back in the field?

[Charnut]

I have been out 3 years and I'm just getting back into the field by starting a HVAC service dept for my friend. I have 25 years in the field.
Thanks, Gary

[Heavyevans]

If the model number of the machine starts with ALS, be very careful. If your techs don't have any time with this machine you could be in for one big headache.

[chillrdude]

If the model number of the machine starts with ALS, be very careful. If your techs don't have any time with this machine you could be in for one big headache.

Bingo we have a winner, if this is an early style machine without the oil separator you could be in for some real fun, the only saving grace may be the fact that it is supposedly grounded, of course what are the chances the gate rotors are still intact?

They should look like this



but probably look like this

[txhvac]

Yes you'll want to pull the compressor plates & have a look at the gate rotors, they have teflon/plastic outer layer(as shown above) the bottom picture is an Oh S***! because if that happens all the wonderful shavings will blow into your condenser & lodge (usually in the subcooler) fun for clean -up.

[Charnut]

Thanks everyone for your help, the model# of chiller is ALS218C27-ER11. The compressor model# SOL175QA13SB Other than that I don't know much about the chiller yet. I will be checking it out next week Also confirming compressor ground. Information I received is from someone else. What should I be looking out for when I go to check it out. It's two circuits and I'm going to start the good circuit and get it ready for the cooling season. Any help again will be appreciated. Thanks Gary

[freonrick]

if you have an oil seperator and lost the gate material you will need a new oil seperator. If no oil seperator and you lost the gate you may be looking at the condenser and subcooler clean up. You will need to check the pressure drop in several places and check design pressure drop for that machine and circuit. Do not leave suction driers in place after clean up. You should have some traininig on this chiller before attacking it. At least have McQuay assist you with it.

[captinsano]

its a 218c the c is the vintage so yes it has a oil seperator.Id suggest you get the Im/Om manuals and read them before you go.

[refrtech]

Compressor grounded on an ALS-C vintage .....HIGHLY unlikely !!!
Without knowing more info my best guess would be a bad SCR and/or D3 starter board ! Not knocking you but if you are not familiar with these particular chillers you may be in for a world of heartache . I would do some more digging before you go condemming a $20K compressor ! The soft starter should trip the compressor out before something happend that would ground the compressor . Good luck to you .

[Charnut]

Thanks for your info, I have not checked out the compressor myself yet. This week I'm going to the site to confirm the compressor ground. As of now all information I have provided is from someone else. Thanks for the help and any other suggestions is appreciated.
Gary

[chiller32]

Boy we sure have lots of McQuay experts on this forum.

[Heavyevans]

Boy we sure have lots of McQuay experts on this forum.

I'm no McQuay expert, I've just had to live with three of these machines. All manufacturers have their turds, IMO this model is the Grand Poobah.