Correct Resolution? Copeland Scroll Compressor / Rust Inhibitor / TEV/TXV Sticking

Paul S_3 · July 2016

i have a few out there ....i find with just a few degrees of subcooling the glass is full on standard applications( evap below or about 10 to 15 feet above)....most of the time ill just use the sweat filter drier that comes with the condensing unit.....i have a job CU on ground air handler about 40 feet above, condenser calls for 11F subcooling....i had to charge to 23F subcooling to fill the glass....on jobs with high vertical lift i always install one.

Techman · July 2016

JUGHNE, "WE" don't put the LLFD/SGMI at the evap because of ALL the extra climbing/crawling/cussin' to go back and forth from the evap to the CU. So, "the path of least resistance" comes into play. "WE" have put in that stuff at the evap on service call problems ,only.Except for when I was experimenting ,that is. A full SG at the CU does not mean that the LL is full at the evap. I do have an "Electronic Sight Glass" for checking the LL at the evap.

margsuarez · July 2016

OP here with another update.

So i had the sizzling/crinkling sound in the area of the filter dryer on the liquid line entering the air handler.

Scheduled a visit for a hot day, about 85 degrees. The tech "T" checked the subcool and computed 2 degrees (manufacturer wants 9 or 10). Added an unknown quantity of refrigerant a few times, waiting 10 minutes between additions. Gauge did not move. Then dumped an unknown quantity of refrigerant. Gauge did not move. Then "Calibrated" his gauge and said subcool was now 4 degrees. Then ran away writing "needs new TXV" on my receipt.

I arrange for 2nd tech to please come and check charge using subcooling. Tech arrives and says he is old school, does not do subcooling. Throws his gauges on and says charge is perfect and leaves. He texted me a photo of the gauges - 150 suction and 250 head. It was a 90 degree day.

Meanwhile it doesn't seem like i can get the indoor temp past 76 degrees or so on an 85 degree day.

So I arrange for a 3rd tech to come and for sure charge by subcooling. He texts me the "after" photo. Air temp was about 85. Liquid line leaving the unit was 92. Low side pressure was 150. High side was 385, which translates to 114deg. So subcool is 22. I told him the manufacturer wants it to be 10. He said this is fine and I should check the Delta T when I get home.

I tried to put the unit through its paces and it was able to bring temps down from 80 to 70 in 8 hours (though it took half that time to go the last 4 degrees).

Delta T this morning was about 20 - 58 coming out of near register and at AHU just above coil. 78 going into return (Stats reported 78).

So it appears that my unit is working.

One question: since subcool is twice what manufacturer recommends - do I need to be worried? I read that flooding the evaporator can cause compressor damage. Why would the tech insist it was not necessary to go by the manufacturer's specification? Should I have them come back?

It is only a 2 year old unit (brand new compressor) so I hate to kill it with an overcharge.

Thank you for your advice
marg

ChrisJ · July 2016

Did the last guy pay attention to the superheat?
That's what will tell you if you have any chance of liquid going back to the compressor.

Subcooling is how much below the condensing point the liquid leaving the condenser is.

When you say the first guy "Then dumped an unknown quantity of refrigerant" what exactly do you mean? What exactly did he do?

margsuarez · July 2016

he loosened the hose on his guage and dumped it into the atmosphere (as have other techs this company has sent).

and why would the 3rd guy (or any of them) not take all possible measurements? including amperage of compressor? especially after I have been throwing such a fuss? sigh.

i think at this point i need to cut them loose and hire my own tech to set up and maintain my unit. but in doing that do i lose anything with warranty coverage or with home depot who sold me the unit? i will make sure to document this latest round of incompetency with home depot.

thanks
marg

Paul S_3 · July 2016

Marg...just like what @ChrisJ said is correct.....the txvs job is to maintain a set superheat....which also protects the compressor preventing liquid floodback....the subcooling is high...evaporator is a couple of feet below condensing unit so 10f should be perfect....since its below if theres a sight glass at the air handler it would probably be full with less subcooling....tech shouldve checked compressor amperage...compressor superheat should be at the very least 10F....also compressor discharge temp below 225F....if all this is is within range compressor should be ok....Like ive told you several times i can swing by next week and set this up for you

ChrisJ · July 2016

Wait,

Home Depot technicians are knowingly and intentionally venting refrigerant?

ChrisJ · July 2016

Paul S said:
Marg....the txvs job is to maintain a set superheat....which also protects the compressor preventing liquid floodback....the subcooling is high...tech shouldve checked compressor amperage...compressor superheat should be at the very least 10F....also discharge temp below 225F....if all this is is within range compressor should be ok....Like ive told you several times i can swing by next week and set this up for you correctly.

Marg,

PLEASE have Paul come by.
Forget Home Depot. Your system is begging you.

margsuarez · July 2016

Paul S and I are talking :-)

njtommy · July 2016

With 150 suction with 410a woul equal 52 degree coil roughly. Which would put your supply air temp around 63-66 degrees roughly. So there is now way to get good dehumidification with that warm of a supply air temp and you will no way get your house down to 72 with the summer time temps.

sometimes the txv or problems with the txv will give you a high suction temp. But you must have subcooled liquid to your txv. Also if the unit is in an attic I always inusulate the liquid line to prevent against the liquid refrigerant picking up heat and start to become saturated.

margsuarez · August 2016

OP here with update to saga. While Home Depot and their installer continue to give me the runaround ("next step" is to have a Rheem certified installer come waste my time I mean verify the overcharged system) I had Paul S come by and fix it already. He recovered about 1 lb and got the subcooling down to spec (was 22, now 11.4). Pressures are up to spec too. Compressor amps fell from almost 9 to 7.1.

How can it be that so many "techs" out there flat out ignore the manufacturer's data plate, travel without temperature gauges (they are in the heating and cooling business!!), or an ammeter?? And by extension don't know why or how to use them?

Probably futile but I will be chastising Home Depot for providing such poor follow through on my issue. They sold me an installation by an installer who cannot properly do their job.

I really appreciate the expertise and generosity on this list. Thanks again.

marg

Correct Resolution? Copeland Scroll Compressor / Rust Inhibitor / TEV/TXV Sticking

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