ReplyAre you saying they upsized the compressors but it has the same condenser ?
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Guys at work (HISD) I have two school that are the same square footage,both school are identical,just different names.Both have 150ton Carrier Flotronic chillers,same age.Both schools cooled just fine till three yrs ago when a new wing was added to both schools.The contractor added a compressor to both chillers on circuit B which brings the tonage on both up to 170tons.Well over the last 3yrs one school still cools great and no problems.The other school is nothing but problems,won't reach setpoint 42degrees.The best it will do on a normal hot day here on the outer part of Houston Tx is 48-49 degrees.This past yr,during May here in the south part summer started early and the humidity was also very high.We brought on the school about 2hrs early just to help out,but by noon time the building just was not cool.If it was overcast or raining that day the chiller would do better.I went through the chiller several times trying to fine the problem,checking everything I could think of.Guys this search for the problem went off/on all summer long.So after all this,I started going over to the other school checking the chiller to see if I could fine something alittle different.Not knowing how to check if maybe the valves were out in one compressor or several, I just started checking amp drawn on each leg of each compressor at both schools.The amps on all compressor were within acouple of amps of each other except compressor A3 at both schools.The B circuit at both schools were close to 60 amps each which the RLA is 60.Now on circuit A, at both schools RLA was 44 amps.At one school compressor A3 was drawing 60 amps.At the school that was not cooling well compressor A3 was drawing 34amps(no unloaders).So,at this time I'm back to thinking that I may have some valves out.I shot the heads w/heat gun and the temps were close to being the same as the others.After afew days went by,I though I would just check the size of the compressors.Took the numbers off of both compressors and called it in to Carrier just to check.Well HECH!!!! The school that cools,A3 is a 40hp(draws 60amps) and the school that does not cool,A3 is a 25hp(34amps).Now,to my question,is this enought of a problem to where I can't get 5-8 degress more of cooling?And why do you thing the reason this compressor is smaller,is the chiller a 170 or not?Sorry for the long story,but this is the short verison---Thanks for any advice CJ
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Are you saying they upsized the compressors but it has the same condenser ?
Professional Member
How do you add a compressor to an existing chiller to increase the tonnage?
To much work with too little time!!!!
Professional Member
Do you mean one of the circs could not be run do to amp draw?? When they ran new wire the other compressor could be fired up??
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Sorry guys for the confusion.The chiller was a 150tons,which consisted of compressors A1,A2,A3,B1,&B2.Carrier up size the chiller by adding compressor B3 and changing the program to recognize the 3rd compressor in circuit#2 which brings the total tonage to 170.These chillers (I'm guessing) the condenser coils and barrel were size to handle the extra compressor,just it was not added or like they just took out compressor B3.(EX. Like their wiring harness,its make to fit several chillers,but not all plugs are use)According to them, the cooler could handle the extra tonage.Please keep in mine that a second school has the same footprint and the same chiller and the same work was done to it also.This school's chiller will reach setpoint on a hot day.The compressor that is only drawing 34amps is A3 which is orginial to the chiller.At the other school compressor A3 is drawing 60amps and its also orginal to the chiller.After calling Carrier w/model numbers of both compressors(A3 at GTE,A3 at TE)The one at TE is a 25hp and the one at GTE is a 40hp.What I'm wondering is if maybe a smaller compressor(A3) was stuck in the chiller by mistake and since its orginal tonage was suppose to be a 150 then maybe its just a 130 ton.Guys thanks for the help and sorry about not explaining myself better----CJ
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How about some model numbers?
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Sorry about that,its 30GTN150 but with the added compressor to the B circuit,its a 170 now.Thanks again,please excuse me for not having all the info---CJ Courtney
Professional Member
I would confirm flow thru barrel. Is it approx. 3.2 gpm per ton?I also would analize each compressor individualy under a full load. Is each compressor mechanicaly in tact? The only way to determine this is assuring that its not unloading ,then checking each for pump down and hold test using each suction service valve and measuring suction superheat at each compressor,measure discharge s.h. at each comp.,check t.d. across each head with an accurate thermocouple thermometer,and I would probably want to pull each head and inspect valves,plates and gaskets. Additionaly make sure Exv's or txv's are feeding properly by measuring evap. s.h. at full load.Lastly I would check sub cooling and condenser fan logic under full load and check with carrier to make sure this machine has been fitted with all the upgrades over the years such as fan baffles,eproms,oil equalizers, etc.
Professional Member*
You stated that one of the existing compressors B-2 is a 40hp at one school and a 25 hp at the other. So you actually had a 135 ton,not a 150 ton, at the second school and now have a 155 ton. Again were did you gain the extra condenser area for the 6th. compressor, you also failed to give us the size of the new additional compressor. What are the design conditions Delta P through the evaporator (chiller barrel) The design GPM's and Delta T (ie) 6# Pressure drop= 420 GPM at 55*F EWT and 44*F LWT= 192 tons. These numbers don't mean anything about your chiller, I'm just using it as an example.-GEO
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to richper HI DAD!
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Thanks for replying to my question ga1279.The compressors is A3 at both schools and they are both orginal to the chillers.At one school compressor A3 draws 60amps(40hp),at another school compressor A3 draws 34amps(25hp).I found the hp differences by calling Carrier and giving them the models #'s off of both A3 compressors.I would think that since both chillers are the same tonnage(suppose to be) then both A3 would be the same size.Guys I may be missing something,so please explain.Carrier installed the extra compressor in each chiller and they also said that the cond. coil and the barrel is big enought to handle the added compressor.Both chillers has a space on the B circuit for another compressor.Is it possible that Carrier sold these chillers that may have been 170tons orginal but just did not add B3 then called it 150 tons?I hate to keep bring this up but both chillers were suppost to be the same.At one school that has the A3 40hp compressor the building stays cool.All other compressors at both schools the amp draw is close to being the same.The school that has the 25hp A3 compressor,that school will not cool.It does has the 10 DT,just that the setpoint is 42 degrees.EWT is 58 & LWT is 48 degrees.The water was balance by Prescision Air,(Johnnie)about two yrs ago then it was check again by another company just last month.Guys again thanks for the help and sorry about not understanding ya'll questions and answers----CJ
Professional Member*
Me thinks you are missing the point, unless another compressor on the chiller at the second school was originally larger by 15 tons, you never had a 150 ton chiller there. You had 135 tons of chiller and were moving about 325 GPM. Again, what is the size of the added compressor? If the chiller wasn't correct to begin with you can't make right untill the original problem is fixed. If you look at the publication it specifies the size for each compressor, fan motor and circuit breaker for that chiller model number and they don't hap-hazardly put any size compressor in the designated space. I know the month of May was hot here, I spent the entire month and June in Pasadena at the plants working 14 hour days.-GEO
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Personally I would need to know model numbers to know anything.
Banned
i would of like to of read what the original post was about
put some spaces between sentences it's hard to keep up
.
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Guys,thanks again for the help.On Monday I will get the numbers off each compressor.And with the help here maybe we can fine the problem.Which that is what I'm wondering about,is that maybe this chiller is not a 150 orginal, but a 135.Even if the model number says it is.Guys on hp rating is it 1ton per hp?Thanks and will be posting Monday afternoon---CJ
Airmechanical:I have two chillers that suppose to be idenical in tonnage,problem is that one elementary school cools just fine,the other does not.Going through all things possible it (I thing) has come down to compressor A3 on both chiller is of different hps.GTE has A3 rated at 40hp and TE has A3 rated at 25hp.Which both chiller were sold as 150tons,this is the short story so if you have any ideals and the reason why that A3 would be smaller please let me know.I just can't imagine why or how this could happen.Thanks Guys CJ
Professional Member*
CJ, it could be very easy to explain, the compressor could have been changed out during the last 3 years, I think you stated earlier that both these chillers are 3 years old, and for some reason they did not have a 06EX275, but they did have an 06EX250, the dead give away is the 2nd. # is a 4cyl and the 1st. is a 6cyl. there is also 06EX265's and 06EX299 and no, the horse power does not correspond to tons only model #'s 6+7 digits represent the cfm of freon that the compressors moves through the cylinders. The other thing I'm puzzled about, how can you just add another compressor to the "B" circuit without adding condenser volume to accept the extra cfm's of gas to be condensed? I know you can change configuration headers to what you want but as they say you can' put 5#'s of s$@! in a 2 pound bag. There is also the extra motor load on the feeder circuit to the chiller. 125% of the largest compressor and add all the FLA's of the rest of the compressors, all the condenser fans and the entire control circuit. If you've added a large motor you have to account for it on the supply wire circuit to the chiller.-GEO
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Guys I could not get the m#'s off of the compressors today,been raining all day long.In the first pic the compressor closest to you is the compressor that was added (B3).In the next pic is the compressor that is A3 and in this chiller its a 25hp where in the other chiller A3 is a 40hp.Third pic is the model of the chiller.Tuesday I will get the m#'s for each compressor.Thanks CJ
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Guys after taking in all the suggestions and ideals,it appairs that maybe this chiller is undersize for the load.As stated in the original post the chiller was a 150ton,then a compressor was added to bring it up to 170tons.Questions were ask,how could this be done without an increase to the barrel and to the condenser coil.I don't have an answer other than Carrier did the work and they said that it will handle the extra compressor.Two ele.schools were fitted w/extra compressor to bring up the tonnage since a small wing was added to both schools.One school cools fine and the other does not,Goodlistener and GA1279 thinking that even though the Model #'s indicate that it started out as a 150 that the problem school may only be a 130ton.So if ya'll will look over the numbers off of each compressor and maybe come up with a totaol tonnage.I just don't know how to do that.A1-06E6265360,A2-O6ED475314,A3-O6ET265360,B1-O6ET299360,B2-O6EA299360,Added Compressor B3-O6EA299360 Thanks CJ
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Do you happen to have the same info off of the other chiller? Is this the good chiller or the bad one ?Originally Posted by CJ Courtney
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Goodlistener,these compressor numbers are from the one that won't reach setpoint.At the other school that cools,A3 is a 40hp and compressor B3 is the same size compressor that was installed in both chillers.I think I will go over to the other school and get those numbers also,just for compersion sake.Is there away to tell what size compressor each one is?Thanks CJ
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