Phase monitor kills compressors?

[penny lane]

Over the past month we have replaced 3 compressors on the same Trane rooftop unit. The 20-ton unit has two compressors and the same compressor has blown three times in a row. Since the unit is 20 years old initially the compressor was thought to have died from natural causes. But when the second one was blown our technicians proclaimed that there was an electrical problem, because the contractor had locked out. Con Edison was brought in to inspect if there had been any spikes, they found nothing wrong. After we noticed that the unit had tripped we called our HVAC service to let them know that then 3-day-old compressor may have just died again. Much to my dismay we found that the new compressor had blow. A recent theory from our technician is the electrical problem is from the phase monitor. Is it possible that the phase monitor has been the source of the problem?

[maxster]

do you have a model on the unit,the phase monitor if as shipped from Trane is inside the reset circuit so the unit should of locked out on an amp spike or brown out situation,are the compressors across the line or PWS on the contactors?if your condensers are dirty within but are surface clean that will trip the module.

[Shophound]

If you've already eaten three compressors, makes me wonder how good of a system clean-up the techs are doing between changeouts.

Your post indicates you may be a building owner or manager vs. a tech, but as such I would be curious as to how well the cause of the original compressor's failure was investigated. So many times when a compressor burns out, it's changed with a poor to fair cleanup procedure, and that's it. The standing assumption is that the thing just died and the new one is the solution. BAD ASSUMPTION!

The overall condition of your system should be assessed. Airflow, coil and blower cleanliness, air filters changed religiously, refrigerant charge, etc. Voltage supply, integrity of all wiring, including what supplies power to the unit, etc.

To answer your question directly, I've never heard of a phase monitor taking out a compressor. I have one each on both of my large split systems and have had no problems with them. Last year one of them tended to trip, reporting "phase loss" each time, which probably saved the compressor. This year's been smooth sailing. I would not remove these monitors unless somebody could prove to me they kill compressors.

[penny lane]

Yes I am a building manager and this old building/HVAC system has lost several compressors over the past few years. The units are maintained regularly and we have our contractually seasonal full check up on everything. Which is not to say that the techs might have done something haphazardly, however with the amount of different people who have been here I would be shocked if something that small was overlooked. The fact that the second stage compressor has blown out 3 consecutive times in the past month is troubling. On two occasions we know for certain that the unit tripped. If the phase monitors tripped the unit to protect it from a spike why are the compressors still grounding out?

The last report speculated that the phase monitor was “bleeding voltage to compressor causing windings to heat up and overload causing grounding, must contact manufacturer.”

It seems typical to blame the manufacturer, but can a phase monitor ground out the compressor by “bleeding voltage?”

[Shophound]

The fact that the second stage compressor has blown out 3 consecutive times in the past month is troubling.

"Second stage compressor"? Are we talking about a tandem compressor arrangement, where both compressors share the same refrigerant charge, same evap and condenser coils, same oil? Or is it on a separate circuit?

If the tech suspects the phase monitor, why doesn't he change it out for a different one along with the compressor? A different brand if he ain't keen on the one in your unit?

Seems to me if there was any "voltage bleeding" of any significance occuring through this monitor between the lines, you'd have a short and the breaker would trip or diconnect fuse blow. The phase monitors I'm familiar with don't feed line voltage through them directly, but are wired in parallel to the compressor contactor line and load sides. Any "voltage bleeding" of any significance between any two of the three lines would in my mind be a direct short.

I would ask the "bleeding voltage" tech to define his terms. Have him draw it out on paper. If he balks or fumbles around, he may not really have the answer. Of course he might be a good BS artist and concoct some wild theory out of his behind to cover same. Or...he might be right. But I just can't see it.

[weezer]

Dear Penny Lane:
Three compressors on same circuits in a few months? One question; are you paying each time or are they being replaced under warranty? As was stated by wisemen formerly, there is a reason for these failures. And the individuals who are replacing them are supposed to figure that out! In the past several years I have not seen nor heard of a phase monitor bleeding voltage. Any so-called leakage across phases will cause an immidiate blown fuse and or breaker. My advice to you is this: Put the brakes on these guys and get a second company to come in to thoroughly troubleshoot this system. Be forwarned, this might take as much as 8 hours to do. If you find that the first company bauched the thing have the second company do the repairs and send the bill to the first company. Good luck.

[dschwab9]

A phase monitor should be breaking the control voltage the contactor, so there shouldn't be any possibility of "Bleed Voltage". I guess it's possible it could be chattering the contactor or something though.

[Chomper]

Originally posted by penny lane

The last report speculated that the phase monitor was “bleeding voltage to compressor causing windings to heat up and overload causing grounding, must contact manufacturer.”


Say Whaaat? This I gotta hear.

[NormChris]

Phase monitors do not cause compressor failures. I know of no relationship between the phase monitor and the compressor that could result in a compressor loss.

Compressors nearly always fail due to a system problem. When a compressor fails the replacement almost always fails unless the actual cause of the problem is located and rectified. I suspect that the actual cause of the first compressor failure was never actually determined.

You don't need people guessing. You need a real professional to tear down the compressors and determine the actual cause of the failure. Tearing down a compressor does not void the compressor warranty. However, you also need the compressor failure investigated by someone who really knows how to perform a compressor failure analysis properly. An electrical failure of a compressor is not always caused by an electrical problem as the first cause.

For example, flooded starts or liquid flood back can cause a loss of lubrication (refrigerant saturated oil is a poor lubricant). The loss of lubrication can cause main bearing wear which can cause the rotor to drop and scrape the stator. This in turn causes winding insulation to wear off and results in a motor burn and electrical failure including the possibility of a grounded compressor motor.

There are other possibilities as well. I am just providing you with an example. Only a professional compressor failure analysis by an experienced professional will give you the answers you need.

Few, very few, HVAC technicians know how to perform a careful failure analysis. Often they don't bother to tear the failed compressor down and if they do, they often are unable to follow the path of the failure to its ultimate cause.

You may be best off if you ship one of the failed compressors to someone who knows what to look for and have them send you a report of their findings.

It is still better if someone comes to your site and takes operating condition measurements of your system to check for refrigerant migration, liquid floodback, flooded starts, current and voltage imbalance, signs of overheating and more. It takes a bit of Sherlock Homes work that the standard HVAC technician is generally not able to perform.

The cause can be determined and solutions found. But it can't be accomplished by a few posts.

Norm

[hvacbear]

Had one that blew out a compressor because our controls contractr wired it into the compressor contactor. The unit has a liquid line solinoid valve controled by a seperate t-stat and a time delay wire in series with the time delay in the phase monitor eventually wired into the low press control for the compressor. When the compressor came on 20 min after the solinoid valve opened dumping liquid into the suction it blew it's valves. There were 5 compressors previously and since we rewired it there have been none for over 2 years.

[NormChris]

Originally posted by hvacbear
Had one that blew out a compressor because our controls contractr wired it into the compressor contactor. The unit has a liquid line solinoid valve controled by a seperate t-stat and a time delay wire in series with the time delay in the phase monitor eventually wired into the low press control for the compressor. When the compressor came on 20 min after the solinoid valve opened dumping liquid into the suction it blew it's valves. There were 5 compressors previously and since we rewired it there have been none for over 2 years.

Right, because you found the problem. But after 5 compressors just makes my point, few technicians are actually capable of performing a proper compressor failure analysis.

I have been on a number of roofs where there were two or three old compressors still sitting next to the system and the compressor in the system had failed yet again. Not only were the technicians unable to find the problem, they did not even have it in them to remove the evidence of the previous failures. That made my job that much easier since I had several compressors to tear down. Yup! All of them had failed from the same ultimate cause.

[mrhvacmechanic]

I would have to agree with weezer.

[hvacbear]

Originally posted by NormChris

Originally posted by hvacbear
Had one that blew out a compressor because our controls contractr wired it into the compressor contactor. The unit has a liquid line solinoid valve controled by a seperate t-stat and a time delay wire in series with the time delay in the phase monitor eventually wired into the low press control for the compressor. When the compressor came on 20 min after the solinoid valve opened dumping liquid into the suction it blew it's valves. There were 5 compressors previously and since we rewired it there have been none for over 2 years.

Right, because you found the problem. But after 5 compressors just makes my point, few technicians are actually capable of performing a proper compressor failure analysis.

I have been on a number of roofs where there were two or three old compressors still sitting next to the system and the compressor in the system had failed yet again. Not only were the technicians unable to find the problem, they did not even have it in them to remove the evidence of the previous failures. That made my job that much easier since I had several compressors to tear down. Yup! All of them had failed from the same ultimate cause.



You've seen a compressor graveyard too?

[NormChris]

Originally posted by hvacbear

Originally posted by NormChris

Originally posted by hvacbear
Had one that blew out a compressor because our controls contractr wired it into the compressor contactor. The unit has a liquid line solinoid valve controled by a seperate t-stat and a time delay wire in series with the time delay in the phase monitor eventually wired into the low press control for the compressor. When the compressor came on 20 min after the solinoid valve opened dumping liquid into the suction it blew it's valves. There were 5 compressors previously and since we rewired it there have been none for over 2 years.

Right, because you found the problem. But after 5 compressors just makes my point, few technicians are actually capable of performing a proper compressor failure analysis.

I have been on a number of roofs where there were two or three old compressors still sitting next to the system and the compressor in the system had failed yet again. Not only were the technicians unable to find the problem, they did not even have it in them to remove the evidence of the previous failures. That made my job that much easier since I had several compressors to tear down. Yup! All of them had failed from the same ultimate cause.



You've seen a compressor graveyard too?


This is a good example why manufacturers like York, Trane and Carrier are calling for technician certification with NATE plus continuing education to keep certification current. The manufacturers want to reduce their warranty costs caused by technicians who don't have the knowledge to properly diagnose field problems or even install systems properly in the first place.

Just look at the vast number of questions posted on this site over such a simple thing as charging a system. Even our tech schools seem to be failing at teaching the most basic of service procedures; system charging.

[james mo]

The more I learn the less I know--Until there is a degree like program developed for the Non-Union HVAC tech, this will always be the case. The NATE certification program falls way short of a comprehensive certification program. I would love to see one of the manufacturers propose a national certification program that required practical testing and continued education programs....AND a better acronym than N.A.T.E.

[james mo]

If I had the Time, money and frankly--The expertise-- I would love to put something like this together and market the hell out of it so the value would be seen to the homeowner, contractor and technician.

[NormChris]

At York we offer all sorts of upgrade training including how to properly perform a detailed compressor failure analysis.

[james mo]

We are a Service Experts Co. and our training resources are lacking. I use the internet and download anything of interest so that I can read it during any down time I have. That is about it. I conduct weekly training meetings for our company and I have a difficult time keeping people interested. I have ordered some packaged programs and put together some labs, but It is so difficult to engage 30 technicians with varying experience levels. Even our York distributor here has little to offer, but they have provided us with some pretty sharp guest speakers. Perhaps I should consider joining a union for the educational opportunities.

[NormChris]

Originally posted by james mo
We are a Service Experts Co. and our training resources are lacking. I use the internet and download anything of interest so that I can read it during any down time I have. That is about it. I conduct weekly training meetings for our company and I have a difficult time keeping people interested. I have ordered some packaged programs and put together some labs, but It is so difficult to engage 30 technicians with varying experience levels. Even our York distributor here has little to offer, but they have provided us with some pretty sharp guest speakers. Perhaps I should consider joining a union for the educational opportunities.


The York distributors have access to a vast number of York factory classes put on by those of us in the technical training department. We can come to the distributors whenever they request us plus we offer York Comfort U classes over the internet. Comfort U classes are also available through York distributors. They are live classes with the instructor speaking live while showing diagrams, photos, illustrations and even equipment on your computer screen. Plus, you can ask the instructor questions real time and get immediate answers. Ask your York distributor to schedule classes for you. If they don't know what you are talking about they should contact York's training department in Norman, OK.

[james mo]

Thank You Norm. I will look into it.

[NormChris]

Originally posted by james mo
Thank You Norm. I will look into it.

I would be glad to come out to any York distributor and put on a compressor failure analysis seminar. But the York distributor must call me to schedule it. We also have many other topics as well.

[hvacbear]

Norm are'nt you in Arizona?

Also we need to educate the customers to demand quality service. The major manufactureers are a good start ,but when it comes to the people writing the checks then the industry will listen. No one would dream of going to an improperly trained doctor for a 100$ physical but they fork over 5000$ to a hack to make them uncomfortable in thier own home. I don't understand:[

[caosesvida]

I agree, the consumer is very lacking in a basic understanding of what is normal. How many of you have heard, " oh yeah my ac guy did the annual check up and added the required freon like he does every year'\"? Hmm a sealed system is not supposed to leak, well you get the point. I do work for a government group. the money they waste is impossible to comprehend. The problem is they really don't want to know because it is not their money. I don't know how you would educate people on such things with life being so busy. THere have been hacks since there was a need for mechanics, With more people there are more hacks. Just lucky for the owner who gets a good one.

[penny lane]

I appreciate all the feedback surrounding the failed compressors at my building. The service company I have tried to leave out for reasons of decorum is Trane. The compressors that are installed here (regularly it seems) are refurbished. Which makes me wonder if the problem is in the compressor, not the phase monitor or some phantom electrical charge. The other possibly that Shophound mentioned is airflow. This building is in the heart of New York City and the unit was built with noise control in mind so it is possible that there is some interference to the airflow. I’d be shocked if we were loosing so many compressors to airflow, but it is a possibility.

[caosesvida]

airflow problems are not rare and can kill a lot of things. I would guess if you are not happy with who you are dealing with in NYC there must be others to take your building on.

[R12rules]

Penny, I assume you are a member of B.O.M.A.

You should be able to network with some other members and find a referral to a good service company.

[hvacker]

I'd listen to NormChris on this. All compressors that fail too soon or any if you have the time and the techsshould be torn down. I remember one I tore down and it reveiled a phase failure. All looked ok until I followed the supply to another subpanel and found a failled buss bar. Beleive the evidence. Bleading phase protectors??? Give me a break.

[NormChris]

Originally posted by penny lane
I appreciate all the feedback surrounding the failed compressors at my building. The service company I have tried to leave out for reasons of decorum is Trane. The compressors that are installed here (regularly it seems) are refurbished. Which makes me wonder if the problem is in the compressor, not the phase monitor or some phantom electrical charge. The other possibly that Shophound mentioned is airflow. This building is in the heart of New York City and the unit was built with noise control in mind so it is possible that there is some interference to the airflow. I’d be shocked if we were loosing so many compressors to airflow, but it is a possibility.

Rebuilt compressors are often of as high a quality as new. If the compressors were rebuilt at a rebuilding facility I would generally discount the compressor as the problem.

Low airflow could be the problem but that is only one of a number of possibilities. If low airflow is the problem that too can be detected as resulting in liquid floodback causing bearing failure and and an electrical failure as one possibility.

The local Trane dealer is not the same as Trane factory service. Just because their name is Trane does not mean they are actually Trane factory personnel.

Unless you specifically locate a technician trained in "compressor failure analysis" you will just be guessing when you change to another service company. You need a verified "expert" in compressor failures.

Norm

[NormChris]

Originally posted by hvacbear
Norm are'nt you in Arizona?

Also we need to educate the customers to demand quality service. The major manufactureers are a good start ,but when it comes to the people writing the checks then the industry will listen. No one would dream of going to an improperly trained doctor for a 100$ physical but they fork over 5000$ to a hack to make them uncomfortable in thier own home. I don't understand:[

No, I work out of the York UPG factory in Oklahoma.

[mam123]

The one thing that jumped into my mind as I read the original post was acid test and clean up if a burnout was the oiginal problem. Just my dos pesos.

[hvacbear]

Sorry I got the wrong Norm

[seaboard]

Never replace a semi-hermetic compressor without pulling the heads and sometimes hand hole covers to inspect the defective compressor and try to determine the cause of the failure. Norm Chris is dead on; many electrical failures root cause are actually mechanical in nature.

As for the phase monitor, I have found many that are incorrectly wired in the control circuit to break the compressor through the normal "hot" wire. If the system has a pump down circuit, that will not catch the compressor and cut it off. It's usually better to break the common wire to all the loads (and make sure you are also killing the liquid line solenoid also).

When dealing with multiple compressor failures, question everything. Don't assume that even the safeties are the correct type for the system. Use an adjustable oil pressure switch that is set to the actual minimum oil pressure you are looking for on the compressor you're working on. I've lost count of how many 9 psi oil pressure switches I've seen on Trane or Copeland compressors that need a minimum of 40 psi net oil pressure. Check every pressure switch and timer for proper operation, and check all solenoids for migration. Also check the system under different load conditions whenever possible. That TXV with great superheat during a heavy load; is it throttling back when the load is lighter.

Norm Chris, I'll be contacting Virginia Air Distributors regarding the possibility of training classes.

[NormChris]

Seaboard:

They may still be working with our old course schedule and list of classes. Just today I have been generating our new course list and it is much more extensive than last years. So Virginia Air will not be aware of our 2004-2005 offerings yet. You could always have them call me.

Norm

[promechhvac]

Wow!What did they forget to do three times?

Such as a acid test, system flush (nu calgon rx11 flush), extra clean filter driers installed on the suction and discharge line. New start components are also needed for the compressor.. contactors, capicitors, pontential relays..

I'm just curious what did the contractor and or factory tech put on the invoice as materials other than the compressor and labor.

Three phase protector gives low/high voltage protection, phase loss, short cycling, momentary power interruptions.
Its designed to save the units life,not kill it.

[hvacker]

I was lucky enough to take a three day Carrier compressor failure seminar in Phoenix about 12 years ago and it changed the way I look at failures completly. If any of you get a chance to take the classes I'd say do it.

[dapper]

Wow!!! This one sounds like a major blunder on the part of the service contractor. These replacements should all be under warranty. Makes you wonder where they are getting the compressors from. You would think that the supplier would send a rep. to check this out.

Just my W.A.G. on this. My bet is it has nothing to do with clean-up, acid etc. too quick, three days or so. Definitely not the phase monitor. (This says a lot about the service tech that is there.) My guess is it has something to do with single phasing, flooding back, or a VERY dirty condenser. Just my 2 cents.

[kevin1313]

I think that I would be looking at floodback.

[sonc]

Originally posted by hvacbear
Had one that blew out a compressor because our controls contractr wired it into the compressor contactor. The unit has a liquid line solinoid valve controled by a seperate t-stat and a time delay wire in series with the time delay in the phase monitor eventually wired into the low press control for the compressor. When the compressor came on 20 min after the solinoid valve opened dumping liquid into the suction it blew it's valves. There were 5 compressors previously and since we rewired it there have been none for over 2 years.


I don't understand how you smacked that compressor, bear.

Liquid injection solenoid right into suction?

[hvacbear]

No, liquid would build up in the evaporator which is fed by two expansion valves that were usually fully open. Twenty min. later when the compressor finally came on a large “slug” of liquid would be pooled up in the evaporator and in an improperly constructed trap. The compressor would get a double whammy from the two slugs in a row pushed by the head pressure 110 degree ambient blows through two wide open txv’s along with help from the suction.

[servman]

Penny,
I would ask to see a compressor tear down report on the compressors that were installed and failed. In order for the compressor re-manufacturer to give your contractor a credit on the failed compressors, they will tear them down to see if it was an error by the contractor that led to the failures. Believe me if they can prove contractor error, which the report will show, they will so they are not giving away new rebuilt compressor to a "parts changer" for free. They report will show what the failure was, where the failure began in the compressor and that will give an idea of what to look for in the system that keeps causing the compressors to fail. Rebuilt compressors can fail though, I had a tech just replace a 50 ton compressor with a rebuild. We have a set procedure for our techs to follow when replacing compressors so I know it was done right (tech could skip steps with out me knowing but most likely not). The compressor grounded out after running for two minutes. The customer being upset that they had no air for several day (1st rebuild was out of stock and took two days to come in plus the time it took for us to do the replacement). I went out that evening with another compressor and another tech and we replaced that compressor. After 30 minutes of run time the second rebuilt compressor grounded out. The next morning I picked up a third rebuilt compressor and replaced the second failed compressor. We made no changes to the system in between the failed rebuit compressor replacements other then new refrigerant filter driers, new refrigerant and contactors. The third compressor has been running for a week. By the way I have paid for all three compressors, supply house was quick to get me the invoices. The company I work for won't get the money back or a credit till a tear down on the compressors has been done.