Changeing out 40 ton condensers

[captn-b]

So i'm changeing out two 40 ton condenser and as always the customer did not want to pay to change the evap coils.
Old unit r-22, new condeser 410. I've done this before on 5 ton and smaller units useing rx-11 to flush and a good triple vac with no problems. But I can't get a comfortable amount of the old oil out even with the flush. Anyone done this before that could give me some advise . I've only got a week to do this and the amount of oil left in the lineset and coil does not give me a warm fuzzy feeling.

[captn-b]

$3000 dollars worth of rx-11 and there is still some oil left in the lineset and coil. I've been told your allowed 10% but I'm still a little worried.

[drife678]

dont wanna change the evap but u are willing to spend 3000 dollars to flush old lineset and coil.. hmmm

[captn-b]

I'm not customer is. Not my first choice but they did'nt want to fork out the money. ( 2 new evap coils $ 118.000)

[drife678]

Holy crap that's a huggggggee bit!@

[ammoniadog]

Was the old system a bad burn-out? If not, I don't see the need for that much RX-11, just plain nitrogen should be good enough (and about $2900.00 cheaper).

The importance of not mixing oils has been much debated on this site. I believe the general consensus is that it is not nearly important as it was first believed. Having a little mineral or AB oil in the system really shouldn't hurt anything.

Having said that, if you haven't done so yet, drilling a hole in the bottom of any suction line traps to drain out any oil that may be in them would probably be a good idea. Also isolate the evaporator from the rest of the piping, remove the txv's, and blow everything out separately.

If the unit doesn't have suction line traps, and too much oil seems to be settling into the evap, I would add them. Also make sure your suction piping isn't too big. Usually R410 equipment needs smaller pipe sizes than R22 equipment. This is also to ensure proper oil return.

[captn-b]

Pipe sizing is coreect according to Trane's install guide and all traps removed. I,ve even blown rag plugs thru lineset to remove oil. It just seems like there is more. Starting up first unit tomorrow. I have reclaim company on standby just incase anything looks weird. I hope that if we run it a bit and then suck it all out and recharge it 90% of the mineral oil should be out.

[captn-b]

Both units would burn out at least 2 compressor every 2-3 years on either circuit. Also condeser coil were gone, close to sea with now coating

[alcomech]

Ok Jay tell him what to do.

[ammoniadog]

Be sure to install big filter driers (liquid and suction) with pressure ports on both sides of them and plan to monitor and change them out as often as necessary until you are confident there is no more acid or junk in the system. I would be more worried about the acid and debris than I would about the separate oil types.

[captn-b]

Got it. Already done and thanks for the advise. I don't smell any acid in the system right now but I've already got two more sets of filters for both units,( liquid and suction).
I'll post how it goes tomorrow and pray nothing major happens.

[mikeacman]

You could get an oil refractometer to measure the ratio of mineral to POE.

I had a split system i started that was built to order and the water cooled condensing unit was filled with mineral instead of poe.
yes ,I questioned it before startup and was ordered to start it .
I had to do many oil changes but with that tool I was confident that in the end i was below 5% mineral oil .

If you've spent that much on flush a couple hundred dollar tool shouldn't kill the job.

[SBKold]

Captn - you have a high concentration of residual flush now as well.

If lineset is long you may need to cut in 50 - 75 ft length and flush from high spots to low always with gravity.

Lots of nitrogen and cutting lineset at low points is the only way that makes sense IMO.

[captn-b]

Thanks for all the advise. I did cut out all the low spots and blew a rag- plug thru the line set. Started one side of one unit today and low and behold no problems. Will be hopefully start other circuits tommorow. I pulled a deep vac 4 times and introduced 410 each time to grab any moisture. Oil at compressers looks good and I am getting 40 degrees at evap coil.

[allstar08]

I have been down this road and I am still on it. I am in the process of replacing both compressors. Is it a Trane?

[captn-b]

Yes and I plan on changeling out compressor oil a couple of times just to make sure it's more poly than mineral

[mikeacman]

Yes and I plan on changeling out compressor oil a couple of times just to make sure it's more poly than mineral

as I mentioned you could use an oil refractometer and know for sure ...

I will shut up now...

[captn-b]

I will be picking one up as you suggested
I definetly see a diferance in the oil and have ordered poly oil in to replace . I just can't believe how expensive it is
Thanks

[captn-b]

It is a Trane and new oil is 4 days out. I hope the compressors last that long there not acting up or over heating I just don't like the look of the oil thru the sight glass

[captn-b]

Allstar08,
What were the problems you that you were having and how many times did you change the oil
I noticed after the first day we had to drain some of the oil because the compressors were getting to full