Mitsubishi City Multi System
Mitsubishi City Multi System
(OP)
Anybody have any experience with this system? It seems like a great option for an historical renovation project I am designing, but there don't seem to be many installations in the US.





RE: Mitsubishi City Multi System
1. Mitsubishi ductless split systems are absolute jewels. A large part of my career has been introducing these units wherever I can. The only problem with their units these days is trying to control the purchasing departments. There are too many cheap knockoffs with atrocious quality. The originals are as good as any refrigerant-based A/C unit ever made.
On the other hand,
2. There is an obvious predisposition of some foreign cultures against chilled water systems. I have seen million+ sq. ft. non-American auto plants go with DX rooftop units, only - when even the worst chilled water system would've saved money on first cost, much less decades of savings from energy and maintenance.
The fact that Hitachi makes the world standard for absorption chillers only makes this observation more bizarre!
Nevertheless, the extremes of engineering and design that go into some of these refrigerant systems are incredible, especially when a simpler chilled water system is inherently superior, cheaper, longer lasting, and more reliable. That's not to say that some American firms are beyond doing the same thing. I have seen outrageously complicated 8-stage DX systems quoted in an effort to keep a project in the "refrigerant only" umbrella of a preferred vendor.
For your specific case, I don't have all of the information needed to make a decision. However, if your application goes beyond 20-30 tons, I would think it a nightmare for future maintenance. Whatever small benefit may be obtained from the heat recovery traits would pale in comparison.
Only Mitsubishi could have the expertise to make a system like this work in the first place.
DISCLAIMER: Please accept my apology if I've offended anyone. An opinion was solicited, and this is simply my own based on my experience and observations.
RE: Mitsubishi City Multi System
RE: Mitsubishi City Multi System
Typically rooftop DX units aren't used so much outside US, and I can't understand the fascination here.
I've worked in Asia and don't think the use of DX systems by asian companies here is driven by a love of packaged DX, efficiency or even first cost, so much as the ridiculous labour cost in the US needed to maintain central plants.
RE: Mitsubishi City Multi System
Wolfie82 does make a good point about historical items, and there may be another - leakage of refrigerant will have zero impact on the preservation of valuable property. However, a leak of chilled water can have disastrous effects. In normal practice, that's an acceptable minor risk - considering the benefits. On the other hand, that may be too much of a risk to contemplate with historical artifacts.
RE: Mitsubishi City Multi System
RE: Mitsubishi City Multi System
Yes, it is too bad that labor issues can "infect" what would otherwise be a simple life-cycle cost judgment.
If the existing unionized work force is in a central plant, then the unitary approach might allow an outsourcing to a cheaper maintenance contractor.
If the existing unionized work force is in the buildings with unitary systems, then a central plant might allow an outsourcing to a cheaper maintenance contractor.
I have experienced it both ways, in fact. Yet as you say, I'm all for central plants.