Mitsu City Multi

tim smith

I have one of these starting this week also, 4 ton od unit w/ 2 & 2.5 indoor ducted. PS the 4 ton does not do simultaneous heat cool. Only the City multi starting at 7 tons. Tim

Paul Fredricks_3

New install

Here are some pics of our 1st Mitubishi City Multi install. The condensing unit is 4 ton, the 2 a'h's are 2 ton each and the wall hung is 1 ton. Interesting system. Shared line set(used the mitsu 1 to 4 line set tee. Left and extra stub for another wall hung to be possibly added later). Pretty cool listening to the compressor ramp up to speed and change speeds as the load changes. There is a lot of piping in the outdoor unit though the pics don't show it very well. The accumulator is about 8" in diameter and 3' long.

Check out the gauges. Low side equates to 37 degrees, but the suction line temp is 27. That's a superheat of -10. I guess that's why the accumulator is so big. We had a factory rep there to fire it off and he said that's normal.

The system seems to work very well. Due to the layout of this very tight house, this system is a perfect fit.

Nick S

That's a very nice install. I have always wanted to find an application for the city multi, but so far I haven't found a practical use for it. I hear they work well for heating and cooling at the same time, in different zones of course. It's a good thing a rep came out to help you. I have installed some mitsu mini splits and I find the charging/start up instructions to be very vague. I can't imagine how a system like that would be charged.

Brad White

When you hear how quiet they are

you will be pleased. The condensing units purr. The evaporators can be drowned out by mouse flatulence they are that quiet.

I have not taken the install course, just the design course but am suitably impressed.

Our first job is going in as we speak in a school. The condensing unit was moved from the roof where we designed it to be, to grade outside classrooms in order to save inside hot work. We are confident that it will be unnoticeable.

Paul Fredricks_3

Oh yeah, love that purrrrrr!

The wall hung unit was a bit louder than I thought it should be, but it was on high speed and probably didn't need to be.

As far as application, I can definitely see the advantages in an office/school setting. Unfortunately we are basically a residential company so chances are we won't be doing that.

In this application there would be no practical way to get ductwork into the room with the wall hung. This was perfect for the room and it gave them another zone to boot. There is an extra port available for another wall hung in the finished attic. It's nice that they can expand the system in the future when they have the cash to spend.

What's also nice is there wasn't much room outside for multiple condensers. The single outdoor unit fit the bill perfectly.

As far as start up goes, you need a laptop to program the condenser so it will recognize the indoor units. Since this is our first system it didn't make sense to put out the extra capital at this time. If we start doing more of them we'll make the investment. With the software you can run the entire system from outside or from any thermostat. Pretty neat!

This house has a counterflow steam system so the heat part of the Mitsu may never be used.

The Wire Nut

Hey Paul...

... nice install and I look forward to hearing more from you as this unit ages! Inverter technology is a given on the mini-split side of the HVAC world, most regular split AC systems are lucky to have a electromechanical 2-stage setting. Yet, being able to run multiple evaps on condenser is a compelling reason for customers to want this technology... less noise, less maintenance, and excellent efficiency for the kinds of HXs they have.

Oh, and you wouldn't by chance have measured the hot gas discharge temperature on that puppy?

Paul Fredricks_3

No, I have no idea. I know all that's in the readout, but I didn't look at it. If I happen to need to look at it again I'll let you know, though I would imagine it's going to change quite a bit with the load.