loud copeland semi hermetic new

[supertek65]

I installed a new copelamatic 30 ton compressor at a school the system is a split system York air cooled condenser 5 years old 50 year old air hndlr 2 evaporator circuits llsv one tied in with the unloader. does not have pump down. Has an accumulator two txv's I vacuumed it down to 500 microns installed new driers as soon as I started it I noticed that the head without the unloader was chattering. 70 degree day at first I had 60 degrees superheat 225 lbs head 30 lbs suction no subcooling. I backed out both txv's trying to lower the head which I did. after adjusting I got my head down to 200 and suction to 65. my superheat at the compressor is 30 degrees.sight glass at evaporator is clear. oil sight glass 3/4 full


my problem is I only have 2 degrees subcooling loaded or unloaded. The compressor still chatters {like a lifter or push rod in a car} The heads seem warm to me 190 degrees shooting them with an infared thermometer. you can leave your hands on them they are not so hot that they will burn you. The motor windings are cool. No vav or freq drive

suction 65-68 lbs
head 200-210 lbs
suction line at compressor 68 deg
liquid line at compressor 98-100 deg
these change loaded or unloaded
superheat 30 deg
subcooling 2 deg
HELP

[airworx]

system has to be charged fully loaded. 10 degrees subcooling and 15 to 25 degrees superheat.
whats your oil pressure. and you donot take subcooling readings on discharge of compressor. liquid line temp minus saturated condensing temp off of guage.

[Shophound]

Yep, you gotta have the comp fully loaded, all condenser fans running, a decent heat load inside, and normal ambient outside to get this kind of system charged correctly.

What you need to be concerned with in addition to that is you've adjusted the TXV's with the system not at full capacity nor possibly fully charged. Now you'll have to go back when you can fully load up the system, bring the charge up, and then babysit the TXV's while making small adjustments and monitoring the evap outlet temp until the EVAP superheat is right. DAMHIKT (Don't Ask Me How I Know This) :D

How loud is the chattering? I got a 25 ton 06E that has a quiet chatter when there's more of a load and the thing is running either fully or partially unloaded. Comp seems to keep going without a hitch (and has been for quite some time), whether it's a hundred degrees out or twenty. It's very subtle, but anyone who knows how 06E's sound without this chatter would pick it up. It's not a sharp sound, just a deviance from the usual harmonics one might hear between the heads while the comp runs. The chatter has never got worse or louder since I first noticed it.

Your cope might be a different story.

[supertek65]

Originally posted by airworx
system has to be charged fully loaded. 10 degrees subcooling and 15 to 25 degrees superheat.
whats your oil pressure. and you donot take subcooling readings on discharge of compressor. liquid line temp minus saturated condensing temp off of guage.


AIRWORX I do not believe that I stated anywhere that I did any subcooling measuring at the compressor and subcooling is not liquid line temp minus saturated condensing temperature off of gage. it is saturated temperature minus liquid line temperature as I stated 110 degree condenser and 108 degree liquid line. 2 degrees subcooling. I checked the system both loaded and unloaded as I stated my subcooling seems to stay at 2 degrees. There is no receiver either. I do understand that I will be back on a warmer day adjusting txv's but maybe I should have just left it running for a couple weeks at 70 degrees of superheat 30 lbs and 300 lbs. NOT!!! My question is what can I do about the 2 deg subcooling. I removed cleaned and correctly positioned the sensing bulbs, do I need to add more refrigerant and dare to open the txv's even more? If I do not get any good answers I will add more refrigerant in hopes to raise my subcooling. Then my suction pressure will go up above 70 lbs but maybe it will not and just my subcooling will come up.
I had a crankcase pressure of 90 lbs and a suction pressure of 70 lbs giving me 20 lbs oil pressure. I am still afraid of the rattle but maybe it will go away too. Also what temperature are the heads supposed to be?

[Shophound]

supertek, I also didn't get where he thought you were getting subcooling from the comp discharge temp. Looking at your profile it would appear you more than likely have a good grasp on how to take this reading and what it means. Problem is, this avenue of communication often has glaring gaps that leads to misunderstanding. I for one read your post late last evening and seemed to hone in on the chattering issue more than anything else.

Now, for some questions: does this system have staged condenser fans? Does it have hot gas bypass for low ambient operation? How clean are the coils? I'm sure you know all these things and others can affect subcooling and charging.

All other things being perfectly normal, no harm in adding refrigerant until you get a subcooling more in line with either OEM or what's expected for this system. It's often said that a clear sight glass is not always indicative of a properly charged system. I've seen clear sight glasses but the subcooling still was not where it should be.


I removed cleaned and correctly positioned the sensing bulbs, do I need to add more refrigerant and dare to open the txv's even more? If I do not get any good answers I will add more refrigerant in hopes to raise my subcooling. Then my suction pressure will go up above 70 lbs but maybe it will not and just my subcooling will come up.

Respectfully, how does "opening up" a TXV increase subcooling? If I'm reading you correctly, you're trying to get more flow through the TXV's by backing out on the spring adjustment stems...right? The way I see it, if you're going for more flow through the evap by opening up the valves, you'll end up with less subcooling, not more. I think you may know why; there's less refrigerant stacked up in the liquid line to be subcooled toward the end of the condenser and into the liquid line. Mass flow rate of refrigerant is greater due to essentially less restriction at the TXV, thereby decreasing time any given portion of refrigerant is sitting in liquid line, giving its heat up to surrounding air.

Try this: get your digital meter out, set it to read temperature, clamp on a type k thermocouple at the evaporator suction outlet, and park yourself by the TXV's after you fully load the compressor (if it can be loaded electrically...does it have suction pressure unloaders or solenoid operated unloaders?). Since you have more than one TXV you'll have to monitor both. Measure the superheat of the evap, then the subcooling of the liquid line approaching the evap. Add refer until you see the superheat drop and the subcooling improve. If the TXV spring stems have been backed out a good ways, you may have to increase spring pressure in the TXV's. Slowly start turning them clockwise and see how that affects both evap superheat and the subcooling. Make a turn or two then wait...monitor...wait some more...monitor...adjust as necessary. 10 degrees superheat at the evap should equate to 15 or more degrees at the compressor.

As for the chatter, hopefully another member with more experience with cope semi-herms might be able to help. Mine is limited to 06E's for the moment.

[supertek65]

Originally posted by shophound
supertek, I also didn't get where he thought you were getting subcooling from the comp discharge temp. Looking at your profile it would appear you more than likely have a good grasp on how to take this reading and what it means. Problem is, this avenue of communication often has glaring gaps that leads to misunderstanding. I for one read your post late last evening and seemed to hone in on the chattering issue more than anything else.

Now, for some questions: does this system have staged condenser fans? Does it have hot gas bypass for low ambient operation? How clean are the coils? I'm sure you know all these things and others can affect subcooling and charging.

All other things being perfectly normal, no harm in adding refrigerant until you get a subcooling more in line with either OEM or what's expected for this system. It's often said that a clear sight glass is not always indicative of a properly charged system. I've seen clear sight glasses but the subcooling still was not where it should be.


I removed cleaned and correctly positioned the sensing bulbs, do I need to add more refrigerant and dare to open the txv's even more? If I do not get any good answers I will add more refrigerant in hopes to raise my subcooling. Then my suction pressure will go up above 70 lbs but maybe it will not and just my subcooling will come up.

Respectfully, how does "opening up" a TXV increase subcooling? If I'm reading you correctly, you're trying to get more flow through the TXV's by backing out on the spring adjustment stems...right? The way I see it, if you're going for more flow through the evap by opening up the valves, you'll end up with less subcooling, not more. I think you may know why; there's less refrigerant stacked up in the liquid line to be subcooled toward the end of the condenser and into the liquid line. Mass flow rate of refrigerant is greater due to essentially less restriction at the TXV, thereby decreasing time any given portion of refrigerant is sitting in liquid line, giving its heat up to surrounding air.

Try this: get your digital meter out, set it to read temperature, clamp on a type k thermocouple at the evaporator suction outlet, and park yourself by the TXV's after you fully load the compressor (if it can be loaded electrically...does it have suction pressure unloaders or solenoid operated unloaders?). Since you have more than one TXV you'll have to monitor both. Measure the superheat of the evap, then the subcooling of the liquid line approaching the evap. Add refer until you see the superheat drop and the subcooling improve. If the TXV spring stems have been backed out a good ways, you may have to increase spring pressure in the TXV's. Slowly start turning them clockwise and see how that affects both evap superheat and the subcooling. Make a turn or two then wait...monitor...wait some more...monitor...adjust as necessary. 10 degrees superheat at the evap should equate to 15 or more degrees at the compressor.

As for the chatter, hopefully another member with more experience with cope semi-herms might be able to help. Mine is limited to 06E's for the moment.

Great answer, you know, sometimes all the training all the classes and all of the certifications in the world and sometimes you still have a brain fart. Yes I was backing out the txv's to increase my suction and drop my head which I achieved, I have put back way more r-22 than I took out I thought that on a low ambient condition low load condition that the 30 deg superheat was ok. I think I was a little afraid to overcharge the unit on a cold day also when the school was going to be closed for three days and the system still calling. OFCOURSE!!! if I back out the txv allowing more refrigerant in the evaporator I will have less in the condenser! thus having less subcooling and my superheat will drop and subcooling raise as I add more refrigerant. Yes the sight glass at the evaporator is clear I have an electric unloader that I can disconnect to load. There are three cond fans one variable one operated by ambient and one by pressure. The condenser coil is a little dirty and like alot of commercial applications hard to clean due to location and chicken wire the maintenance man installed around the unit. The hot gas bypass does not work because it never opened when I had 10 lbs suction. Thank you for you advice, you are clearly a very trained smart technician. I worked 8 hours overtime when I finished the compressor and many more in the days before. I am tired and was hoping to talk to a smart tech who could reaffirm what I was thinking. I will park myself infront of the txv's while monitoring sh and sc. We have had problems with this account and I do not want to be the one to lose it. I guess I will see about the noise. Thanks again Frank

[airworx]

2 degrees subcooling means either your low charged, txv adjustment opened to much or running unloaded.
when adjusting txv as your superheat falls close off txv that will raise subcooling and superheat, tring to maintain 10 degrees subcooling and around 20 degrees superheat.
i would first make sure you dont have a broken valve which usually has a rattle to it. if youre having a lot of vibration and noise then i would suspect a broken piston head or rod.

[Shophound]

Frank, thanks for your kind words. Glad mine were helpful, post back the outcome when you go back on this system again.

As for the hot gas bypass, if it is like the one shown in the upper right hand corner of this photo...

http://pic12.picturetrail.com:80/VOL431/789398/5133498/67100031.jpg


...that particular valve is adjustable. Trick is, you turn the valve clockwise to raise the suction pressure setpoint at which it will open and begin admitting hot gas to the evap, and counterclockwise to lower the pressure (hope I got that order right...going from memory :D).
When I first encountered one of these valves and having no prior instruction how to adjust them, I broke out my digital thermometer and type k clamp probe and placed it downstream of the valve. I started backing out the valve with no result. Cranked 'er down and not long after the temp of the pipe started ticking up. Since I was at the same site all the time, I was able to keep coming back to this thing to dial it in until it worked great when the outdoor ambients dropped.

By the way, any idea what took out the compressor you replaced?

[richper]

The first thing I would do is front seat the suction service valve and pull the compressor down to 15 to 20 inches vac. and stop the comp. to see if it holds.The next thing I would do is measure the temp. differance across each head fully loaded remember you are looking for a substantial T.D. from the bottom of each head to the top if the cylinders underneath are performing correctly.If no measurable t.d., pull the head in question. My suspect here is broken valves, snaped rod or other form of internal damage.And yes I have seen this before on new compressors or this could occur on start up.It sounds like your not pumping on all cylinders.As far as sub cooling goes,on many older systems sub cooling is just not atainable. I know I'm going to get some heat for this but remember when energy was cheap systems where just not designed for alot of subcooling,and even though your condensing unit is 5 years old your evap is 50.I also suspect the system is over charged in an attempt to get your readings correct. Once all the above is confirmed, I would change the txv's , check all the obvious, air flow, coils,duct work ,etc., charge until the glass is clear ,then with a substantial heat load on the evap and a minimum of 100 degrees condensing temp. check for 20 degrees compressor super heat, but not until the system has had a chance to stabilize operation running under thse conditions.To many times techs. try to get these readings wth an un stable system. It's like the surgeon operating on a patient with no b. p., they wont do it most of the time until the patient is stable. The last thing I would do is set up the unloaders and hot gas, check the controls and this should assure a good running system.