View Full Version : York YT series open drive 600 ton chiller
04-11-2005, 02:44 PM
I'm seeking some input on the control strategy for our York YT 600 ton open drive chiller equipped with a solid state starter. The machine currently has 27,000 hours and 1475 starts and is used for comfort cooling in a correctional institution. The unit runs continuously May-October.
In an effort to conserve energy, I have been thinking that the unit could be shut down in the evening and restarted in the morning as conditions require. However, I'm under the impression that cycling the machine is not good.
During low load conditions we consistantly see loads in the 25-30% range. A VFD is out of the question due to budgetary reasons at this time, but would be the obvious solution.
Any input is appreciated.
04-11-2005, 06:47 PM
the vfd package installed by york or other qualified people can be set up as an energy savings contract where they will basically give you the drive with the payments coming from the energy savings. usual time is about three years and after that its free energy savings and better control. your local energy office may be interested in this if approached in the correct manner. As far as shutting down at night, from my experience this is not a good idea due to the inmates getting upset and threatening lawsuits due to being uncomfortable.
With a variable speed drive and variable orfice kit, you can run that machine using 55 degree tower water @ .190 kw/ton. If only York's marketing was as good as Trane's...
04-11-2005, 08:15 PM
maustin, if you have a solid state starter it will not hurt to stop chiller for the night and then start in morning. Most of the stress on a motor occurs due to starting with across line or Wye-Delta starters. More so with the X-line. Due to the high in--rush current and torques developed. Using a Solid state starter you slowly build up to full speed, greatly reducing any damaging effect to motor.
CDO, how many KW do you think you will burning out at the tower to get that 55 deg water? If you can even get that low on a summer day/night? I think you are greatly over exagerating your .190 KW/ton claim. Especially if you include the tower KW.
04-11-2005, 08:34 PM
up here in the north there's lot of times when we can get 55 tower water . especially in may,sep, and oct .
04-11-2005, 08:42 PM
double bubble: up here in the north there's lot of times when we can get 55 tower water . especially in may,sep, and oct .
I am sure you can, but how much energy do ya use getting it? Wouldn't it be better to run 75-80 and still get .4-.5 kw/ton?
Think about it...All tower manufacturer's use a 7 degree approach. The cooling tower is typically sized to match the full load capacity of the chiller @ 95 degree outdoor ambient air temperature. When you run that same chiller at part load conditions (where it runs most of the time) when it's less than 95 degrees outside, you can take advantage of lower tower water temperatures.
Trane uses a fixed orifice in their machines which causes refrigerant to stack in the condenser and starve the evaporator when cold tower water is used. Trane machines need that high delta pressure between the condenser and evaporator to push that refrigerant thru that orifice. York uses a vsd on the compressor and variable orifice in the liquid line along with level switch in the evaporator to maintain a stable refrigerant level in the evaporator. Lower delta pressure = lower compressor output = lower kw/ton.
04-11-2005, 09:58 PM
I think you might be missing my point, Colder tower water does not just magically happen when OA drops. You still need to run a fan. I have York YK's and CVHE/F also under contract. The YK towers are Mammoth in proportion to the Trane towers, in order to get that "cold" tower temp. Bigger towers=more$$$ (Capitol and Operating)
Both manuf. run about .4-.5 KW per ton under part load.
And the Yorks have the liq level control, but not VSD.
It does magically appear when you compare wet bulb and dry bulb temps. Both manufacturers also use 3 gpm/ton for the condenser flow rate, so tower size should be the same.
I didn't believe it at first either... I was Tranewashed for years...
04-11-2005, 10:50 PM
So now I guess your York washed, thats alright. I like Yorks also, my point was its kind of a tradeoff. You spend money running a tower fan to get a slightly lower KW/ton.
Your spending a dime to save 10 cents.
I love working on Yorks though, I always seem to have plenty of work. Especially with all the threaded fittings, seals, oil leaks, etc,etc. They are good for the service guys.
I do like their VSD's, pretty Bulletproof now.
04-18-2005, 07:38 PM
I would recommend NOT shuttign down at nights, the cost of stop/starting a machine is in thwe thousands, much cheaper to leave it running, but again the vsd drives are a great unit, I've been trained specifically on the the York VSD and it seems pretty damn good, especially energy savings.
04-18-2005, 11:31 PM
Get ahold of Yorks regional sales department and ask for the energy saving rebate offers the local power company is offering. Most major manufacturers will perform the work at no cost to the customer. The payback is covered in the rebate checks you sign over. We do it all the time in california on contract basis for 3-5 years.
04-20-2005, 10:39 AM
This seems like the place to be...
Any body know ball park how much refrigerant might be lost in a year on a 750 ton York centrifugal that is about 10 years old and run in the summer for HVAC chill water? Just trying to get an idea because I don't have one.
04-20-2005, 05:43 PM
Well it all depends on how big the leak is, pressurize the machine and see if you can find the leak, lot's of times the shaft seal will leak on those, but again just do a leak check and see if it is a tight machine.
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