Daikin McQuay WMC magnetic bearing chiller: start, loaded run, stop 

Thanks for the comment. We're seeing significant energy savings (greater than 40%), especially on moderate days where outside temperature and humidity are relatively low.

Hi Brendan, Capacity is controlled by a number of things - motor speed, vane position and the electronic expansion valve. To prevent stalling of the refrigerant flow, the compressor speed never drops below 80% except during startup. One compressor will run up to full load, then the system starts the second compressor to add capacity, at which point both compressors work together to maintain the leaving chilled water temperature. In this video, as building load is satisfied, both compressors ramp down to about 80%, then one compressor will turn off, leaving the remaining compressor to handle the load. As load decreases further, the one remaining compressor will slow itself down from 100% to about 80%, before finally shutting off. Note that motor speed and output capacity are related, but not at a 1:1 ratio. 80% speed is the lowest and 100% speed is maximum capacity (except during startup).

@@bnkwupt how about unloading capacity?

@@abdulkhadermohin5978 I’d estimate that it can unload down to about 15% of its cooling capacity.

This installation has fixed speed pumps for both chilled water and condenser water. We have another installation with variable speed pumps, but it doesn't actually seem to save any energy on these particular machines.

Energy efficiency of the chiller depends on the design of the unit. For example, this centrifugal unit is most efficient when the condenser water temperature is at or below 72F. Screw chillers like higher condenser water. Some people will tell you that it's better to run a slower cooling tower fan speed and hotter condenser water temperature, but for this particular type of unit, the energy required to run the tower fan at a higher speed is far less than the energy required to run the compressors at a higher speed (to overcome the increased lift pressure from the higher condenser water temp). It's complicated, but most manufacturers will provide charts that explain the most efficient operating conditions.

I've done dozens of plants, and there isn't any one answer to this. Plant efficiency depends on dozens of factors, and the most successful optimization efforts I've worked with have involved complex models of a particular plant and optimizing all the flows and temperatures through the system based on load, weather, chiller type, etc. And unfortunately, all of this will be for naught if the connected loads are operating efficiently. Efficiency is everything from the cooling tower fan to the damper on the VAV box.

It's rated at 180 tons nominal capacity. Max compressor RPM depends on condenser water temperature. Perhaps 35,000?

mzungu Writes this unit doesn't monitor flow rate other than yes/no.

Each compressor has a super-capacitor that will maintain the magnetic field long enough for the compressors to coast down to a safe and complete stop. This unit is running straight water with treatment chemicals - no glycol. Glycol has is less efficient at transferring heat and is unnecessary in this application because all of the chilled water plumbing is inside of the building. If the chiller was outside, glycol would be necessary.

Marty Lynchian at maximum output, it only consumes about 110,000 watts. On an average summer day, maybe 60,000. No need to notify the power company.

In this application, the pumps and the tower fan are controlled by the chiller, as shown on the screen.

It just indicates that they're wide open. I don't know why they chose to display a value greater than 100%.

VeeDubTDI Refrigerant pre-rotation takes place after 100% IGV and it is done for compressor efficiency improvement purposes

Thanks. I wasn't aware of that.

They most certainly did use Danfoss Turbocor compressors on the WMC.

You have to exit the machine’s software and return to the Windows screen. From there, you’d configure your screen saver settings just like you would on a desktop PC. I’ve moved on from this job so I can’t give you a step-by-step.

@@bnkwupt oh that’s easy then, just how do you exit out of the program haha

@@therandomchannel6103 open the control box and press the small power switch on the computer inside near where you’d insert a USB drive. This will turn the display computer off. Then press again to turn it on. It should boot into Windows. There might be an easier way but I don’t remember what it is.

@@bnkwupt awesome I’ll give that a try next time I’m over there. Thank you!

Me too, please!

How to reset?!

Sorry, I only have the operator password, not the technician password.

Where are your chiller videos, Craig?

It was a McQuay when we bought it and it says both Daikin and McQuay on the unit. Daikin bought the McQuay factory in Staunton, VA where this unit was manufactured. Just because Daikin bought out McQuay doesn’t mean this unit isn’t a McQuay.