Anybody have bad experience with Multistack (Trane) Modular Chillers?

[acjourneyman]

Whatever you think you have covered, you don't. If you don't want to install a closed loop cooling tower than you will always have problems. It doesn't matter what or how many strainers you install because the junkstack strainers are finer and if you install finer mesh ones ahead of them than you will be cleaning them everyday.

[drivewizard]

Yea i've got the strainers covered. I am going to use a self cleaning filter that purges when differential pressure across the filter is greater than a specified value. The cleaning cycle lasts about 20 seconds, in this process the condenser water loop loses water, but there is an automatic make up on it so were fine. It's just a matter of piping the waste line somewhere.

If it is basically a wye strainer with a solenoid valve to blow down, well, good luck with that.
If you were filtering out marbles that may work, but I have never seen a blowdown alone be able to clean a filter that has cottonwood, and other small debris that likes to get hung up in the strainer holes. You may end up losing a whole Sh** load of water trying.
Usually you have to remove the screen from housing and spend some time at the slop sink cleaning.
Let us know how this works out for you.

[Paulinator]

I will definitely keep you guys posted on how this works out. The filter i am using is a specialty filter from AMIAD filtration systems. We are capable of filtering from 800 to 10 microns ( i have not gone into the details yet, as i still need to meet with the client with my proposed solution).

[hvacdoctor]

Here is the deal, if you have good water and clean tower loop with a good strainer they run good. If not they are nightmares and do require a good chemical cleaning annually. Customers often get miss led because its new...Had quite a few compressors go bad, heat exchanger ruptures, etc.

Again good clean water is the key. my 2 cent opinion.

[flange]

While I agree that the multistack has been very maintenance heavy, and has caused many, many contractors heartache just hearing the name, it really sounds like the lad has his mind made up. There are other options, but whatever. On a seperate note, I heard recently that multi was going to switch to shell and tube design due to the lousy reputation of their products in the past, but have no verification of that yet. The good news is that he will be creating manhours for some contractor, hopefully one that knows better than to offer full maintenance on these crappy machines. The bad news is that he is stubborn enough to not listen to good advice, and may get a bad rap himself for specifying this heap.

[Paulinator]

So, the thing is.... I am only the junior here asking for some food for thought. I have spoken to the senior engineer here who is signing and stamping the drawings about this post and he feels confident in this design. If it was me running the show, i might take a second look at other options like Klove was speaking about. Since i am not running the show, the only thing i can do is voice my opinion and let him make the ultimate decision.

[jd 07]

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.

[will smith]

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.

[Randy S.]

Closed loop condensers, or you'll be sorry.

[wd1958]

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.

[maxster]

Trane covers them in some areas,and a couple of Trane engineers were the founders of the Multistack group in LaCrosse

[chillrdude]

So, the thing is.... I am only the junior here asking for some food for thought. I have spoken to the senior engineer here who is signing and stamping the drawings about this post and he feels confident in this design. If it was me running the show, i might take a second look at other options like Klove was speaking about. Since i am not running the show, the only thing i can do is voice my opinion and let him make the ultimate decision.

Dont worry he is not the first engineer that thought he knew it all and had all the answers

Does he really think he will get a straight answer from the Trane rep who is marketing and selling him the MultiStack

[brooklyntech]

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.

[directman]

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.

[mustardman]

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.

[RC20]

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.

[D'Laine]

I got hired to do consulting on an existing office tower in my city. Chiller is up in penthouse and I am going to provide the client with modular chillers because they can fit in the elevator and up the stairs. I was wondering if anyone has ever had any experience with these machines and if it was a good or bad experience. Thanks!

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.

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.

D.

[mustardman]

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.

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.

D.

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.

[RC20]

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. That’s 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

[mrhvacmechanic]

I have work on Multi's since they first arrived her in NYC.
Never had problems with their operations.

However, as stated in other posts, " closed cond loop!" or you will have problems.