Milk Cooler

ddlong1286@yahoo.com · March 2009

Hi all,

Working an a Mueller milk cooler again. It has two condensers, M#A51-HPF. 5HP copeland comp. with subcooling valve.(valve to maintain 10 degrees subcooling, with flooded evap.) Complaint is not cooling fast enough!

The milk was 50 degrees when I arrived. The cond. unit that is piped to I believe the side coil of the tank had these readings:60lbs suction, 180lbs liquid line, 12 degrees subcooling, 5 degrees superheat, 99 degrees discharge line temp.

The cond. unit piped to the bottom coil in the tank had these readings:60lbs suction, 210lbs liquid line, over 20 degrees subcooling, 1 degree superheat, 155 degree discharge line temp. 24 amps.

Ambient both units, 56 degrees. Only one fan operating on each unit, second fan on fan cycle switch.(on 250 lbs, off 200 lbs. 21 amps.

I covered the cond. coil to bring up the hi side pressure. on the first cond. both pressures came up and the hi side would fluctuate from 245 to 200 lbs., the second fan would not cycle on and the suction pressure held steady at 70 lbs. The sc would go to zero with the hi side pressure flucuation. Amp draw would go up also. along with discharge line temp.

That leads me to believe that that comp. is operating properly, except the low discharge line temp. and hi side fluctuation when cond. covered. Subcooling and superheat are within parameters as is the amp draw. Any ideas about what might be wrong with this unit? I am inclined to replace the comp? Should I recover the charge and see if I am low?

The other unit I also covered the coil and both pressures came up. Only the second fan cycled on this unit. Subcooling stayed above 20 degrees, amp draw came up and down with fan cycling. I am inclined to believe the subcooling valve is bad(only 2 years old). This unit had a leak on the suction service valve, which I fixed this afternoon, recovered 17 lbs 14 oz. Total charge 19.5 lbs.

So do I replace the subcooling valve? again! or is something else going on that I am missing?

I also took readings when the milk hit 45*, suction pressures lower of course but sc and sh not changed.

I will try to moniter this a while tonight if anyone has questions.

Thanks
Don in MO

don_205 · March 2009

Hi Don

How have you been? All your numbers seen to point to a low charge.

Keep this in mind when working with flooded system.There should be no superheat!

Add some more refrigerant untill you get the subcool to about 20 and then see if the superheat goes to zero.

ddlong1286@yahoo.com · March 2009

Milk cooler

I recovered the charge in the leak unit and had 18 lbs. Holds 19.5, so it is fixed and charged up.

The first unit will be getting a new comp or cond. unit. Th price for the new Hi-performs went up almost $2000.

Looked at the other tank yesterday(Fri) and condemned the comp on one of the cond. on it. Pretty much the same conditions. Recovered to check charge and it was right on 19 lbs. The lower tank unit was working pretty good.

So with two comp. bad, I don't see them replacing the cond units with the cost so high and milk not really making a lot of money right now. You never know though, I told the
Dairy Farmers Agent in charge of these milk stations that he needed to change out some of the older units or ones that have given him the most trouble last year. Gave him a price on a new cond. and they put it off. It will only get more expensive as time goes on. These four condensers are 1985 models and three have the original compressors. I would say they got their monies worth!!

I know sometimes these coolers are a pain, but I like doing refrigeration and they are the only refrigeration I'm seeing right now.

Of course if it wasn't for them I wouldn't have had any hours thursday and friday. Work is getting scarce here.

Thanks for the reply Don, I'll try not to be so long between posts. I have some pics from that MRI trailer from last year that lost the "head master". We are going to replace the evap coil and fix a leak in the hot gas bypass line. Evap is full of holes, love to see the white foam on the end sheet!-not!!

Don in MO

jhfsdhf2171289 · March 2009

milk coolers

don where we are in NH donot see milk coolers anymore all farms sold off for housing. when did work on them and for that matter anything that I consider out of the ordinary or equiment I might not look at again I will take measurements and store them in a book I have had for about 25 years so when i go back I always have refrence points save time on troubleshooting and I know how the equipment runs when all is 100% JON

don_205 · March 2009

Inefficent comp

You know one when you see it.The pressure differential between suction and discharge decays.
Suction pressure increase while head pressure decreases.
You will have some amp but nothing like it would under a load.

You know its typical in this business to have them wanting you to keep milking it along.No pun intended.

I think you are going to find your talent even more in demand this coming year.Make sure your service ticket are written up on the high side.

Not many people are going to take the time and address the issue as you are doing.That type of talent should be rewarded.

Take care Don.Wishing you well this coming year.

Milk Cooler

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