Reply to Thread

Well we're cookin now, high 90's in HOTLANTA now, so the air ciculation troubles are showing uo better. One solution is to run the end units and leave the middle for back up........

I would liek to know how the smoke test was done, as in were did you set the smoke bomb, ground, top of unit, side mid way ?????

Right now there is so much dirt form construction its just watch and see which one trips first. I don;t panic on this, ain't nothing you gona do to control mother nature !!!

Great insight, thank you all..........

That's the first time I've heard of the plastic cap coming off of the EXV head. Must have been an isolated instance.

You need a laptop to reconfigure the unit to run without the fan inverter.

Need opinion on this:
You have a year round constant heat load, load average is 110 % split betweeen two machines 7/24. With O/A temps in the winter dropping as low as 25 but averaging 38 - 48, would you realy need the cond. fan VFD to be in place. I am looking at the cost of replacment of these items, verses doing away with them. We are seeing a replacment of at least one to two every lighting storm in the area. Lets face it, those VFDs are not the highest quality item on the market. .....

Next pet pea of mine now that I am working these little monsters, it the EXV. COME ON TRANE >>>>> a small tip of epoxy gell to hold the little plastic cover cap over the hole at the top of the head. Was washing one the other day and that littel disk came off, WELL, do ya really need me to tell ya what happens when water gets into the top of an EXV !!! Whats the in field remady for this one ???? We are going with the high dollar fix, called a 3' pvc pipe cap with a short piece of 3' pipe to set over the EXV........
Only problem is the PVC only comes in white !!! I'm gona paint them RED !!!

Any takers, place your order now, supplys are limited........... Custom colors are at a higher price.......

Hey "The Chiller Man", were did you place your smoke at, we did a simular test here and the smoke went in and up out the fans, I balieve they set them on the ground. I balieve it would be better to set them on the outer edge of the machine, up by the fans.

Also all, if ya bypass the VFD will the unit still bring in the relay and run the "A" fans......with out repograming ....

Also, we have those new interface pannels, touch screen, small ones, is it possible to reprogram at the screen with out a lap top ????

Smaoke bombs I LIKE that !!!

Originally Posted by Mongo and me

The machines are spaced 10 feet between each at set of three each, so two sets of three, the three are seperated 10 feet, the sets are over 100 feet between. all are sitting on pads on the ground. no reall wall toubles. Today you could walk down between the two running side by side and see 110 air being sucked in........ Yep there may be a recirculation problem !!!!

We had (4) 400 ton RTAC chillers side by side, surrounded by a wall, and covered by a steel grate overhead. We suspected an air re-circulation problem. We used smoke bombs to visualize the airflow and confirmed re-circulation.

The customer added ducts on top of the fan deck to direct the discharge air up higher to get it away from the coils.

Originally Posted by Mongo and me

And its not Delta T, here in Atlanta its AIR TRAN T !!!! LOL..........

I thought it was DIXIE-T!

I worked a startup on one of the first RTACs in our area central FL. It had very high head. After exhausting everything I knew and coming up empty I called tech support. Should have called first. They knew they had a problem. After sending data file and mod and sn conversation went something like this. Did you check the oil level on the separator. Yes is within the factory specified limits. OK do this remove oil until it is below min oil level. You can always add more. I removed over 5 gal oil before machine settled down. Apparently oil overcharge blows on through separator and trashes heat transfer on condenser from refrigerant side. Maybe it was just an isolated incident with new product etc,etc. If you have access to software level that you can graph and analyze operating conditions it will go a long way to understanding the problem. Otherwise call Trane. Could be a warranty issue or will be when you start loosing compressors.

Originally Posted by servicetrane

the problem of high oil temperature and / or high pressure in a machine I had in Cancun, but was due to a high level of oil.

Good point .But if the charges of refrigerant and oil havent been monkeyed with my money is on the combination of dirty coils , wrong rotation and or non rotation of fans and air recirculation problems .
But if the history of the chillers is full of recharge and or oil issues etc etc . then it could be oil/refrigerant/noncondensibles etc .

the problem of high oil temperature and / or high pressure in a machine I had in Cancun, but was due to a high level of oil.

It's impossible to over-stress the importance of verifying all condenser fans are running when they should. The only way to do it is climb up there and feel the air flow off each fan. Don't just walk it while looking down- feel it and make sure you're not feeling reverse flow. I have seen others make this mistake several times. Your mop handle with a short piece of string or ribbon may work, but you won't be able to also inspect the fan wiring this way. I think a combination of these two methods would be OK. I have 2 RTAC200's on my building's roof, about 100 feet apart, in Montgomery, AL. I've seen head pressure of about 210 psig at full load on a 95 degree day. Any hotter, both chillers are running.

And so now, the picture is starting to clear up a little.
Good point on delta across coil, we will see on a regular day temperature of 95, the entering air could be from 95 to 115 depending on were you are standing along the side of the unit between the two running. YES, there is definetly an air circulation issue. Anyoine want to take a stab at fixing it !!!!
picture three RTAC 500's side by side with 12 feet between them, mostly open area around them.

As for the oil temp. I understand the safety shut down, very well done. Now move me along into the load and unload of the female valve ????? I am recalling reading that valve was a 30% step after start up ?? Book not in front of me, so be polite about my memory !!

Keep it comin, and yes I can use probes to take temp readings, will mor then likly use a mop handle with a thermister taped to the end. May need an exstention thermister cord !!

I use 2 wire ties....one around the bracket that is very loose, and the second around the wires and looped through the first wire tie.

oil temperature issue: as the head pressure goes up due to dirty coils (assume constant evaporator load) the refrigerant flow rate drops. when it drops, each molecule of refrigerant has to absorb more heat than it normally would. the higher discharge temperature heats up the oil that is also passing through the compressor. since there isn't an oil cooler, you trip on high oil temperature diagnostics before you trip on high head pressure diagnostics...just one of those weird little things that the engineers probably didn't mean to have in there...but there it is.

keep the condensers clean...it sucks to keep them clean...but it sucks to have a chiller down too.

please be careful using the idea of 'condenser split'. using a PERFECTLY CLEAN condenser coil and ALL of the fans running, you can use condenser split as a diagnostic/performance tool...but why? the condenser is perfectly clean!

because some of the fans may not be running, the condenser split may appear unusually high. also, because your condenser fans get different run times, the condenser can get dirtier under some fans than others...so which leaving air temperature would you use? the hottest one? the coldest one?

condenser split is a great tool for residential and very small commercial systems with 1 or MAYBE 2 fans. not for a chiller with 20+ condenser fans.


as for the condenser fan wiring...get a bunch of wire ties and cut out all of the old factory-installed wire ties. install the new wire ties properly with snug (not death grip) wire tie tension and save yourself the headaches. after you get a few fans done, it can go pretty quick...you will probably be doing it later anyway.

As for hot and humid, I am in Houston so its very hot and humid most of the year down here.

[QUOTE=Mongo and me;10527852]do you think I'm soem kind of sping chicken to climb up inside and take temp readings........or Wilt Chamberlin reaching over the top fan disharge !!!
I can tall ya from my cyber finger, the air is Hotter comin out then goin in !!!!

I don't climb in to check air in. You can check air in on the outside coils and for air out either a ladder or if chiller is at ground level, my thermometer that came with my fluke I can reach and get air from fan discharge.

send me soem duct tape !!!

Yep, to fix issue where wires rubbed and caused blown fuses, I cut the ties and placed some insulation tape and then retied the wires back. By the way I did that on all fans on the chillers which I had one fan go down due to this that way I prevented any future failures on the other fans. And the split is air in condenser and air out.

do you think I'm soem kind of sping chicken to climb up inside and take temp readings........or Wilt Chamberlin reaching over the top fan disharge !!!
I can tall ya from my cyber finger, the air is Hotter comin out then goin in !!!!

Picky Picky Picky !!!!

And its not Delta T, here in Atlanta its AIR TRAN T !!!! LOL..........

Delta T across the coil.