I have several dozen that my company takes care of. Airstacks and Multistacks. If you treat them properly and keep the water treated you will have no problems. The only problem jobs I have are ones where the owner has ignored the recomended operation procedures. So go ahead and treat it properly and it will give you a good long run. I have some in my company that are over 15 years old and running fine.
Not familiar with how Trane utilizes them, but as far as MultiStack goes, they are as good as they are engineered. As long as the pumping circuits are sized right, Multistacks are as good as they come. Most problems I've encountered have been because mechanical "engineers" have cut corners with flow rates, and we've seen problems on the cooling/condensing sides as a result. Multistack provides an excellent product-the problem some folks have with them is usually due to the fact that they don't understand the product appliocation.
Closed loop condensers, or you'll be sorry.
God Bless our Veterans
God Bless the USA
I service alot of these Multistack Chillers. I would recommend isolating the Cooling Tower water with a heat exchanger or install a Closed Loop Cooling Tower. If the Multistack condenser will only see Closed Loop water your maintenace will be cut down alot.
Trane covers them in some areas,and a couple of Trane engineers were the founders of the Multistack group in LaCrosse
Dont worry he is not the first engineer that thought he knew it all and had all the answers
Originally Posted by Paulinator
Does he really think he will get a straight answer from the Trane rep who is marketing and selling him the MultiStack
If you dont stand behind our troops, please feel free...........to stand in front of them.
Hey if you really want to sell the customer on something new & fancy, I got something for you. See if Trane can cut down the tonnage, switch to 123, sell them a CH530 upgrade, then sell them an Adaptiview, so they can monitor they revamped chiller. If your commisioned based, sell them a Tracer ugrade while your there. Try RTHD screws, u can get one thats 200 tons- 134a, quality machine. Last but not least, if u have to go Mulitstack- closed loop, otherwise, the service guys who have to deal with these units will be cursing you ( the engineer who speced the job); because you know building owners are on top of water treatment!!! After they burn a compressor or two then they understand the importance. Have fun!!! Cherio as they say in England.
Might want to have a look at a Smardt Chiller using the Turbocor oilless compressor. They come in compact and fit in the elevator just like the Multi crap. Use R134A and are more efficient than a screw and since they don't have any oil in the system you won't have to worry about oil loss or loss of efficiency due to oil in the ref. Comp draws less than 5 amps on start up due to liquid cooled VFD on the motor and it gets its best efficiency at part load conditions where most chillers run most of the time. Most importantly it uses shell and tube cond and evap so no problem with cleaning or keeping clean as per the multi crap and its plate heat exchangers.
My personal opinion is Multistacks are a service mans dream and an owners nightmare. Tons of maintenance and lots of repairs. However they do make a turbocore chiller as well and word is they have come out with a shell and tube model as well. Idon't believe the shell and tube is modular though.
Originally Posted by directman
Keep in mind that Multi Stack is not the only unit out there, and possibly not the best.
Clima Cool actually looks to be very well done, though it does use the Brazed Plate heat exchanger, they offer both a filter (passive and an auto type like you mentioned) and they offer a reverse flush valve system, with the isolation, that is intended to purge them of the crud. I cannot say it works or not.
Mokon Iceman and Edwards Engineering also make those type units. One at least uses shell and tube heat exchangers. Worth a look at all options and pick the best that suits the situation.
Google Modular Chillers, and you see a number of options come up.
My Multistack experience...
I've serviced the same 2 module, 100 ton Multistack since 1995. It's run non-stop, and then with a fair bit of cycling for the duration. Replaced a lot of contactors and 4 Bristol compressors. That was caused by bad contactors bouncing. Kept the 60 mesh strainers clean, about twice a year. Still running well. It's been quite good for the last few years.
Originally Posted by Paulinator
I'd allow for a sliding gantry over top of the compressors to allow change-out with a chain-fall. Otherwise it's too hard to almost impossible. I'd not want to change out a plate heat-exchanger though. But my records show no particular degeneration.
No better or worse than other equipment.
Originally Posted by D'Laine
I have done a few plate frame exchangers they come from the factory with the 90 welded on so the really crappy weld is done for you. A word of caution make sure when you order to specify right side or left side don;t ask me how I know this. Other than that its way easier than it looks.
I just got a quote back from Mokon (we are looking at 20-30 tons size units to suit our application).
Interesting that while you cannot get digital scrolls in the 15 tons size (for the 30 ton unit) they do offer digitally controlled hot gas bypass. Thats always been a bit of a pain to keep adjusted.
Also they offer Allan Bradley controls. Non proprietary is our preference. Not endorsing them, just good stuff to know.
The plan is to build a broad range of these for the file, not so much for quotes or price, but to see what features are offered and compare them. The down select the one that best fits the most critical features. In our case
1. Non proprietary controls if possible
2. Failure mode if the master controller (if any) fails. I.e. we need to be able to keep cooling working even if its really ugly control.
3. Manual override capability (if we have to hardwire it and have someone run it if we cannot get good failure modes)
note: Our Trane screw has such a proprietary setup there is virtually no way to make it work manually.
4/5: These two are so close that its hard to separate the
1. Quality components
2. Maintenance ease (i.e. how hard is it to remove the brazed plate if you have to)
so far in the tonnage we are looking at, they offer the Copeland scrolls.
I have had Bristol units years ago (recips). They were good despite severe abuse. No idea now